EXHIBIT 1.2

                         Metromedia Fiber Network, Inc.

                              Class A Common Stock
                           (par value $.01 per share)

                             Underwriting Agreement

                                                              New York, New York

                                                               November 12, 1999

SALOMON SMITH BARNEY INC.
CREDIT SUISSE FIRST BOSTON CORPORATION
DEUTSCHE BANK SECURITIES INC.
DONALDSON, LUFKIN & JENRETTE
        SECURITIES CORPORATION
GOLDMAN, SACHS & CO.
MERRILL LYNCH, PIERCE, FENNER & SMITH
      INCORPORATED
As Representatives of the several Underwriters,
c/o   Salomon Smith Barney Inc.
      388 Greenwich Street
      New York, New York 10013

Ladies and Gentlemen:

            Certain stockholders of Metromedia Fiber Network, Inc., a Delaware
corporation (the "Company"), named in Schedule I hereto (the "Selling
Stockholders") severally propose to sell to the underwriters named in Schedule
II hereto (the "Underwriters"), for whom Salomon Smith Barney Inc., Credit
Suisse First Boston Corporation, Deutsche Bank Securities Inc., Donaldson,
Lufkin & Jenrette Securities Corporation, Goldman, Sachs & Co. and Merrill
Lynch, Pierce, Fenner & Smith Incorporated (the "Representatives") are acting as
representatives, 4,895,000 shares of Class A Common Stock, par value $.01 per
share, of the Company (the "Underwritten Securities"). The Selling Stockholders
named in Schedule I hereto also propose to grant to the Underwriters an option
to purchase up to 734,250 additional


shares of Common Stock to cover over-allotments (the "Option Securities," and
together with the Underwritten Securities, the "Securities"). To the extent
there are no additional Underwriters listed on Schedule II other than you, the
term Representatives as used herein shall mean you, as Underwriters, and the
terms Representatives and Underwriters shall mean either the singular or plural
as the context requires. In addition, to the extent that there is not more than
one Selling Stockholder named in Schedule I, the term Selling Stockholder shall
mean either the singular or plural. The use of the neuter in this Agreement
shall include the feminine and masculine wherever appropriate. Any reference
herein to the Registration Statement, the Basic Prospectus, any Preliminary
Final Prospectus or the Final Prospectus shall be deemed to refer to and include
the documents incorporated or deemed to be incorporated by reference therein
pursuant to Item 12 of Form S-3 which were filed under the Exchange Act on or
before the Effective Date of the Registration Statement or the issue date of the
Basic Prospectus, any Preliminary Final Prospectus or the Final Prospectus, as
the case may be (the "Incorporated Documents"); and any reference herein to the
terms "amend", "amendment" or "supplement" with respect to the Registration
Statement, the Basic Prospectus, any Preliminary Final Prospectus or the Final
Prospectus shall be deemed to refer to and include the filing of any document
under the Exchange Act after the Effective Date of the Registration Statement or
the issue date of the Basic Prospectus, any Preliminary Final Prospectus or the
Final Prospectus, as the case may be, deemed to be incorporated therein by
reference. Certain terms used herein are defined in Section 17 hereof.

      1. Representations and Warranties. (i) The Company represents and warrants
to, and agrees with, each Underwriter as set forth below in this Section 1.

            (a) The Company meets the requirements for use of Form S-3 under the
      Act and has prepared and filed with the Commission a Registration
      Statement (File No. 333-89087) on Form S-3, including a Basic Prospectus,
      for registration under the Act of the offering and sale of the Securities.
      The Company may have filed one or more amendments thereto, including a
      Preliminary Final Prospectus, each of which has previously been furnished
      to you. The Company will next file with the Commission one of the
      following: (1) after the Effective Date of such Registration Statement, a
      final prospectus supplement relating to the Securities in accordance with
      Rules 430A and 424(b), (2) prior to the Effective Date of such
      Registration Statement, an amendment to such Registration Statement
      (including the form of final prospectus supplement) or (3) a final
      prospectus in accordance with Rules 415 and 424(b). In the case of clause
      (1), the Company has included in such Registration Statement, as amended
      at the Effective Date, all information (other than Rule 430A Information)
      required by the Act and the rules there under to be included in such
      Registration Statement and the Final Prospectus. As filed, such final
      prospectus supplement or such amendment and form of


                                       2


      final prospectus supplement shall contain all Rule 430A Information,
      together with all other such required information, and, except to the
      extent the Representatives shall agree in writing to a modification,
      shall be in all substantive respects in the form furnished to you prior to
      the Execution Time or, to the extent not completed at the Execution Time,
      shall contain only such specific additional information and other changes
      (beyond that contained in the Basic Prospectus and any Preliminary Final
      Prospectus) as the Company has advised you, prior to the Execution Time,
      will be included or made therein. The Registration Statement, at the
      Execution Time, meets the requirements set forth in Rule 415(a)(1)(x).

            (b) On the Effective Date, the Registration Statement did or will,
      and when the Final Prospectus is first filed (if required) in accordance
      with Rule 424(b) and on the Closing Date (as defined herein), the Final
      Prospectus (and any supplement thereto) will, comply in all material
      respects with the applicable requirements of the Act, the Exchange Act and
      the respective rules thereunder; on the Execution Time, the Registration
      Statement, as supplemented by any prospectus supplement filed pursuant to
      Rule 424(b), did not or will not contain any untrue statement of a
      material fact or omit to state any material fact necessary to make the
      statements therein, in light of the circumstances under which they were
      made, not misleading; on the Effective Date, the Final Prospectus, if not
      filed pursuant to Rule 424(b), will not, and on the date of any filing
      pursuant to Rule 424(b) and on the Closing Date, the Final Prospectus
      (together with any supplement thereto) will not, include any untrue
      statement of a material fact or omit to state a material fact necessary in
      order to make the statements therein, in the light of the circumstances
      under which they were made, not misleading; provided, however, that the
      Company and the Selling Stockholders make no representations or warranties
      as to the information contained in or omitted from the Registration
      Statement or the Final Prospectus (or any amendment or supplement thereto)
      in reliance upon and in conformity with information furnished in writing
      to the Company by or on behalf of any Underwriter through the
      Representatives specifically for inclusion therein, it being understood
      and agreed that the only such information is that described as such in
      Section 8(b) of this Agreement.

            (c) The Incorporated Documents heretofore filed, when they were
      filed (or, if any amendment with respect to any such document was filed,
      when such amendment was filed), conformed in all material respects with
      the requirements of the Exchange Act and the rules and regulations
      thereunder, any further Incorporated Documents so filed will, when they
      are filed, conform in all material respects with the requirements of the
      Exchange Act and the rules and regulations thereunder; no such document
      when it was filed (or, if an amendment with respect to any such document
      was filed, when such


                                        3


      amendment was filed), contained an untrue statement of a material fact or
      omitted to state a material fact necessary to make the statements therein,
      in light of the circumstances under which they were made, not misleading;
      and no such further document, when it is filed, will contain an untrue
      statement of a material fact or will omit to state a material fact
      required to be stated therein or necessary in order to make the statements
      therein not misleading.

            (d) Each of the Company and its subsidiaries has been duly
      incorporated and is validly existing as a corporation or limited liability
      company in good standing under the laws of the jurisdiction in which it is
      chartered or organized with full corporate power and authority to own or
      lease, as the case may be, and to operate its properties and conduct its
      business as described in the Final Prospectus (as then amended or
      supplemented), and is duly qualified to do business as a foreign
      corporation or limited liability company and is in good standing under the
      laws of each jurisdiction which requires such qualification, except where
      the failure to be so qualified would not have, singly or in the aggregate,
      a material adverse effect on the condition (financial or otherwise),
      prospects, earnings, business or properties of the Company and its
      subsidiaries, taken as a whole, whether or not arising from transactions
      in the ordinary course of business.

            (e) All the outstanding shares of capital stock of each subsidiary
      that is a corporation have been duly and validly authorized and issued and
      are fully paid and nonassessable, and, except as otherwise set forth in
      the Final Prospectus, all outstanding shares of capital stock of the
      subsidiaries are owned by the Company either directly or through wholly
      owned subsidiaries free and clear of any perfected security interest and,
      to the knowledge of the Company, any other security interests, claims,
      liens or encumbrances.

            (f) The Company's authorized capitalization is as set forth in the
      Final Prospectus under the heading "Capitalization".

            (g) There is no franchise, contract or other document of a character
      required to be described in the Registration Statement or Final
      Prospectus, or to be filed as an exhibit thereto, which is not described
      or filed as required. The statements in the Final Prospectus under the
      headings "Certain United States Federal Income Tax Considerations",
      "Business--Regulation," "Business-Franchise, License and Related
      Agreements," "Business-Regulation of International Operations,"
      "Description of Capital Stock" and "Business--Legal Proceedings" fairly
      summarize the matters therein described in all material respects.


                                       4


            (h) This Agreement has been duly authorized, executed and delivered
      by the Company; the Securities have been duly and validly authorized by
      the Company; the holders of outstanding shares of capital stock of the
      Company are not entitled to preemptive or other rights to subscribe for
      the Securities; and, except as set forth in the Final Prospectus, no
      options, warrants or other rights to purchase, agreements or other
      obligations to issue, or rights to convert any obligation into or exchange
      any securities for, shares of capital stock of or ownership interests in
      the Company are outstanding.

            (i) The Company is not, and after giving effect to the offering and
      sale of the Securities and the application of the proceeds thereof as
      described in the Final Prospectus, will not be, an "investment company"
      required to be registered under the Investment Company Act of 1940, as
      amended, without taking account of any exemption arising out of the number
      of holders of the Company's securities.

            (j) No consent, approval, authorization, filing with or order of any
      court or governmental agency or body is required in connection with the
      transactions contemplated herein, except such as will be obtained under
      the Act in connection with the registration of the Securities, and such as
      may be required under the blue sky laws of any jurisdiction in connection
      with the purchase and distribution of the Securities by the Underwriters
      in the manner contemplated herein or in the Final Prospectus.

            (k) None of the execution and delivery of this Agreement, the sale
      of the Securities, nor the consummation of any of the transactions
      contemplated herein or the fulfillment of the terms hereof, will conflict
      with, result in a breach or violation or imposition of any lien, charge or
      encumbrance upon any property or assets of the Company or any of its
      subsidiaries, pursuant to (i) the charter or by-laws of the Company or any
      of its subsidiaries; (ii) the terms of any indenture, contract, lease,
      mortgage, deed of trust, note agreement, loan agreement or other
      agreement, obligation, condition, covenant or instrument to which the
      Company or any of its subsidiaries is a party or bound or to which its or
      their property is subject; or (iii) any statute, law, rule, regulation,
      judgment, order or decree applicable to the Company or any of its
      subsidiaries of any court, regulatory body, administrative agency,
      governmental body, arbitrator or other authority having jurisdiction over
      the Company or any of its subsidiaries or any of its or their properties,
      except in the case of clauses (ii) and (iii), as could not be reasonably
      expected to have, singly or in the aggregate, a material adverse effect on
      the condition (financial or otherwise), prospects, earnings, business or
      properties of the Company and its subsidiaries, taken as a whole, whether
      or not arising from transactions in the ordinary course of business.


                                       5


            (l) The Securities conform as to legal matters to the description
      thereof contained in the Final Prospectus.

            (m) The consolidated historical financial statements of the Company
      and its consolidated subsidiaries included in the Final Prospectus present
      fairly in all material respects the financial condition, results of
      operations and cash flows of the Company as of the dates and for the
      periods indicated and have been prepared in conformity with generally
      accepted accounting principles applied on a consistent basis throughout
      the periods involved (except as otherwise noted therein). The selected
      financial data set forth under the caption "Selected Consolidated
      Financial Data" in the Final Prospectus fairly present, on the basis
      stated in the Final Prospectus, the information included therein.

            (n) The pro forma financial statements included in the Final
      Prospectus include assumptions that provide a reasonable basis for
      presenting the significant effects directly attributable to the
      transactions and events described therein, the related pro forma
      adjustments give appropriate effect to those assumptions, and the pro
      forma adjustments reflect the proper application of those adjustments to
      the historical financial statement amounts in the pro forma financial
      statements included in the Final Prospectus. The pro forma financial
      statements included in the Final Prospectus comply as to form in all
      material respects with the applicable accounting requirements of
      Regulation S-X under the Act and the pro forma adjustments have been
      properly applied to the historical amounts in the compilation of those
      statements.

            (o) No action, suit or proceeding by or before any court or
      governmental agency, authority or body or any arbitrator involving the
      Company or any of its subsidiaries or its or their property is pending or,
      to the best knowledge of the Company, threatened that (i) could reasonably
      be expected to have a material adverse effect on the performance of this
      Agreement or the consummation of any of the transactions contemplated
      hereby; or (ii) could reasonably be expected to have a material adverse
      effect on the condition (financial or otherwise), prospects, earnings,
      business or properties of the Company and its subsidiaries, taken as a
      whole, whether or not arising from transactions in the ordinary course of
      business, except as set forth in or contemplated in the Final Prospectus
      (exclusive of any amendment or supplement thereto).

            (p) Except as described in the Final Prospectus, each of the Company
      and each of its subsidiaries owns, licenses, leases or has obtained


                                       6


      rights-of-way for all such properties as are necessary to the conduct of
      its operations as presently conducted. The Company and each of its
      subsidiaries has good and marketable title, free and clear of all liens or
      encumbrances, to all property and assets described in the Final Prospectus
      as being owned by it on the date hereof and such properties and assets are
      in good repair and suitable for use as so described except as set forth in
      the Final Prospectus. All leases to which the Company or its subsidiaries
      are a party are valid and binding (subject to applicable bankruptcy,
      reorganization, insolvency, moratorium, fraudulent conveyance or other
      laws affecting creditors' rights generally from time to time in effect and
      to general principles of equity) and no default has occurred or is
      continuing thereunder which could have, singly or in the aggregate, a
      material adverse effect on the condition (financial or otherwise),
      prospects, earnings, business or properties of the Company and its
      subsidiaries, taken as a whole, whether or not arising from transactions
      in the ordinary course of business, and the Company and each subsidiary
      enjoy peaceful and undisturbed possession under all such leases to which
      any of them is a party as lessee with such exceptions as do not interfere
      materially with the use made by the Company or such subsidiary.

            (q) Neither the Company nor any subsidiary is in violation or
      default of (i) any provision of its charter or bylaws; (ii) the terms of
      any indenture, contract, lease, mortgage, deed of trust, note agreement,
      loan agreement or other agreement, obligation, condition, covenant or
      instrument to which it is a party or bound or to which its property is
      subject; or (iii) any statute, law, rule, regulation, judgment, order or
      decree applicable to the Company or any of its subsidiaries of any court,
      regulatory body, administrative agency, governmental body, arbitrator or
      other authority having jurisdiction over the Company or such subsidiary or
      any of its properties, as applicable, except in the case of clauses (ii)
      and (iii) as could not be reasonably expected to have, singly or in the
      aggregate, a material adverse effect on the condition (financial or
      otherwise), prospects, earnings, business or properties of the Company and
      its subsidiaries, taken as a whole, whether or not arising from
      transactions in the ordinary course of business.

            (r) Each of (i) Deloitte & Touche LLP, (ii) Ernst & Young LLP, and
      (iii) PriceWaterhouseCoopers LLP, each of whom have audited certain
      financial statements of the Company and its consolidated subsidiaries or
      its acquired entities, as the case may be, and delivered their report with
      respect to the audited consolidated financial statements included and/or
      incorporated by reference in the Final Prospectus are independent public
      accountants with respect to the Company within the meaning of the Act and
      the applicable published rules and regulations thereunder.


                                       7


            (s) The Company and each subsidiary has filed all foreign, federal,
      state and local tax returns that are required to be filed or has requested
      extensions thereof except in any case in which the failure so to file
      would not have, singly or in the aggregate, a material adverse effect on
      the condition (financial or otherwise), prospects, earnings, business or
      properties of the Company and its subsidiaries, taken as a whole, whether
      or not arising from transactions in the ordinary course of business, and
      has paid all taxes required to be paid by it and any other assessment,
      fine or penalty levied against it, to the extent that any of the foregoing
      is due and payable, except for any such assessment, fine or penalty that
      is currently being contested in good faith or as would not have, singly or
      in the aggregate, a material adverse effect on the condition (financial or
      otherwise), prospects, earnings, business or properties of the Company and
      its subsidiaries, taken as a whole, whether or not arising from
      transactions in the ordinary course of business.

            (t) No labor problem or dispute with the employees of the Company or
      any of its subsidiaries exists or is threatened or imminent that could
      have, singly or in the aggregate, a material adverse effect on the
      condition (financial or otherwise), prospects, earnings, business or
      properties of the Company and its subsidiaries, taken as a whole, whether
      or not arising from transactions in the ordinary course of business.

            (u) There are no transfer taxes or other similar fees or charges
      under Federal law or the laws of any state, or any political subdivision
      thereof, required to be paid in connection with the execution and delivery
      of this Agreement or the issuance by the Company or sale by the Company of
      the Securities.

            (v) The Company and each of its subsidiaries are insured by insurers
      of recognized financial responsibility against such losses and risks and
      in such amounts as are prudent and customary in the businesses in which
      they are engaged; all policies of insurance and fidelity or surety bonds
      insuring the Company or any of its subsidiaries or their respective
      businesses, assets, employees, officers and directors are in full force
      and effect; the Company and its subsidiaries are in compliance with the
      terms of such policies and instruments in all material respects; and there
      are no claims by the Company or any of its subsidiaries under any such
      policy or instrument as to which any insurance company is denying
      liability or defending under a reservation of rights clause; neither the
      Company nor any such subsidiary has been refused any insurance coverage
      sought or applied for; and neither the Company nor any such subsidiary has
      any reason to believe that it will not be able to renew its existing
      insurance coverage as and when such coverage expires or to obtain similar
      coverage from similar insurers as may be neces-


                                       8


      sary to continue its business at a cost that would not have, singly or in
      the aggregate, a material adverse effect on the condition (financial or
      otherwise), prospects, earnings, business or properties of the Company and
      its subsidiaries, taken as a whole, whether or not arising from
      transactions in the ordinary course of business.

            (w) Except as described in the Final Prospectus, no subsidiary of
      the Company is currently prohibited, directly or indirectly, from paying
      any dividends to the Company, from making any other distribution on such
      subsidiary's capital stock, from repaying to the Company any loans or
      advances to such subsidiary from the Company or from transferring any of
      such subsidiary's property or assets to the Company or any other
      subsidiary of the Company.

            (x) Except as described in the Final Prospectus, the Company and its
      subsidiaries (i) possess the certificates, authorizations, approvals,
      franchises, licenses, rights-of-way and permits issued by the appropriate
      federal, state, local or foreign regulatory authorities necessary to
      conduct their respective businesses as presently conducted, (ii) are not
      in violation of any such certificates, authorizations, approvals,
      franchises, licenses, rights-of-way and permits, except where such
      violation would not have a material adverse effect on the condition
      (financial or otherwise), prospects, earnings, business or properties of
      the Company and its subsidiaries, taken as a whole, whether or not arising
      from transactions in the ordinary course of business and (iii) have not
      received any notice of proceedings relating to the revocation or
      modification of any such certificate, authorization, approval, franchise,
      license, right-of-way or permit which, singly or in the aggregate, if the
      subject of an unfavorable decision, ruling or finding, would have a
      material adverse effect on the condition (financial or otherwise),
      prospects, earnings, business or properties of the Company and its
      subsidiaries, taken as a whole, whether or not arising from transactions
      in the ordinary course of business.

            (y) The Company and its subsidiaries possess or have applied for the
      patents, patent rights, licenses, inventions, copyrights, know-how
      (including trade secrets and other unpatented and/or unpatentable
      proprietary or confidential information, systems or procedures),
      trademarks, service marks and trade names (collectively, "Intellectual
      Property") presently employed by them in connection with the businesses
      now operated by them, and neither the Company nor any of the Subsidiaries
      has received any notice of infringement of or conflict with asserted
      rights of others with respect to the foregoing except as could not have,
      singly or in the aggregate, a material adverse effect on the condition
      (financial or otherwise), prospects, earnings, business or properties of
      the Company and its subsidiaries, taken as a whole, whether or


                                       9


      not arising from transactions in the ordinary course of business. To the
      Company's knowledge, the use of such Intellectual Property in connection
      with the business and operations of the Company and its subsidiaries does
      not infringe on the rights of any person.

            (z) The Company and each of its subsidiaries maintain a system of
      internal accounting controls sufficient to provide reasonable assurance
      that (i) transactions are executed in accordance with management's general
      or specific authorizations; (ii) transactions are recorded as necessary to
      permit preparation of financial statements in conformity with generally
      accepted accounting principles and to maintain asset accountability; (iii)
      access to assets is permitted only in accordance with management's general
      or specific authorization; and (iv) the recorded accountability for assets
      is compared with the existing assets at reasonable intervals and
      appropriate action is taken with respect to any differences.

            (aa) The Company and its subsidiaries are (i) in compliance with any
      and all applicable foreign, federal, state and local laws and regulations
      relating to the protection of human health and safety, the environment or
      hazardous or toxic substances or wastes, pollutants or contaminants
      ("Environmental Laws"); (ii) have received and are in compliance with all
      permits, licenses or other approvals required of them under applicable
      Environmental Laws to conduct their respective businesses as described in
      the Final Prospectus; and (iii) have not received notice of any actual or
      potential liability for the investigation or remediation of any disposal
      or release of hazardous or toxic substances or wastes, pollutants or
      contaminants, except where such non-compliance with Environmental Laws,
      failure to receive required permits, licenses or other approvals, or
      liability would not, individually or in the aggregate, have a material
      adverse effect on the condition (financial or otherwise), prospects,
      earnings, business or properties of the Company and its subsidiaries,
      taken as a whole, whether or not arising from transactions in the ordinary
      course of business; neither the Company nor any of the subsidiaries has
      been notified that it has been named as a "potentially responsible party"
      under the Comprehensive Environmental Response, Compensation, and
      Liability Act of 1980, as amended.

            (bb) Except as described in the Final Prospectus, the Company and
      its subsidiaries are implementing a comprehensive, detailed program to
      analyze and address the risk that the computer hardware and software used
      by them may be unable to recognize and properly execute date-sensitive
      functions involving certain dates prior to and any dates after December
      31, 1999 (the "Year 2000 Problem"), and reasonably believe that such risk
      will be remedied on a timely basis without material expense and will not
      have a


                                       10


      material adverse effect upon the financial condition and results of
      operations of the Company and its subsidiaries, taken as a whole.

            (cc) Each of the Company and its subsidiaries has fulfilled its
      obligations, if any, under the minimum funding standards of Section 302 of
      the United States Employee Retirement Income Security Act of 1974, as
      amended ("ERISA"), and the regulations and published interpretations
      thereunder with respect to each "plan" (as defined in Section 3(3) of
      ERISA and such regulations and published interpretations) in which
      employees of the Company and its subsidiaries are eligible to participate
      and each such plan is in compliance in all material respects with the
      presently applicable provisions of ERISA and such regulations and
      published interpretations; the Company and its subsidiaries have not
      incurred any unpaid liability to the Pension Benefit Guaranty Corporation
      (other than for the payment of premiums in the ordinary course) or to any
      such plan under Title IV of ERISA.

            (dd) The subsidiaries listed on Schedule III attached hereto are the
      only significant subsidiaries of the Company as defined in Rule 1-02 of
      Regulation S-X (individually, a "Subsidiary" and collectively, the
      "Subsidiaries").

            (ee) None of the transactions contemplated by this Agreement will
      violate or result in a violation of Section 7 of the Exchange Act, or any
      regulation promulgated thereunder, including, without limitation,
      Regulations T, U and X of the Board of Governors of the Federal Reserve
      System.

            (ff) Neither the Company nor any of the subsidiaries is a "holding
      company" or a "subsidiary company" of a holding company, or an "affiliate"
      thereof required to be registered under the Public Utility Holding Company
      Act of 1935, as amended.

            (gg) Neither the Company nor any of its subsidiaries nor, to the
      Company's knowledge, any employee or agent of the Company or any
      subsidiary has made any payment of funds of the Company or any subsidiary
      or received or retained any funds in violation of any provision of the
      Foreign Corrupt Practices Act of 1977, as amended.

            (hh) No "nationally recognized statistical rating organization" as
      such term is defined for purposes of Rule 436(g)(2) under the Act has
      indicated to the Company that it is considering (i) the downgrading,
      suspension or withdrawal of, or any review for a possible change that does
      not indicate the direction of the possible change in, any rating assigned
      to the


                                       11


      Company or any securities of the Company or (ii) any change in the outlook
      for any rating of the Company or any securities of the Company.

            (ii) No relationship, direct or indirect, exists between or among
      the Company or any of its subsidiaries on the one hand, and the directors,
      officers, stockholders, customers or suppliers of the Company or any of
      its subsidiaries on the other hand, which is required by the Act to be
      described in the Final Prospectus which is not so described.

            (jj) The Company has not taken, directly or indirectly, any action
      designed to cause or which has constituted or which might reasonably be
      expected to cause or result, under the Exchange Act or otherwise, in the
      stabilization or manipulation of the price of any security of the Company
      to facilitate the sale or resale of the Securities.

            (kk) Except as may have been waived, no holders of securities of the
      Company have rights to the registration of such securities under the
      Registration Statement.

            (ll) The securities being sold by the Selling Stockholders are duly
      listed, and admitted and authorized for trading, on the NASDAQ National
      Market.

      Any certificate signed by any officer of the Company and delivered to the
Representatives or counsel for the Underwriters in connection with the offering
of the Securities shall be deemed a representation and warranty by the Company,
as to matters covered thereby, to each Underwriter.

      (ii) Each Selling Stockholder severally and not jointly represents and
warrants to, and agrees with, each Underwriter that:

            (a) Such Selling Stockholder is, or prior to the Closing will be,
      the record and beneficial owner of the Securities to be sold by it
      hereunder free and clear of all liens, encumbrances, equities and claims
      and has duly indorsed such Securities in blank, and, assuming that each
      Underwriter acquires its interest in the Securities it has purchased from
      such Selling Stockholder in good faith without notice of any adverse claim
      (within the meaning of Section 8-105 of the New York Uniform Commercial
      Code ("UCC")), each Underwriter that has purchased such Securities
      delivered on the Closing Date to The Depository Trust Company or other
      securities intermediary (assuming such are securities intermediaries
      within the meaning of Section 8-102(14) of the UCC) by making payment
      therefor as provided herein, and that has had such Securities credited by
      book entry to the securi-


                                       12


      ties account or accounts (within the meaning of Section 8-501(a) of the
      UCC) of such Underwriter maintained by The Depository Trust Company or
      such other securities intermediary will have acquired a security
      entitlement (within the meaning of Section 8-102(a)(17) of the UCC) to
      such Securities purchased by such Underwriter, and no action based on an
      adverse claim (within the meaning of Section 8-102(a)(1) and Section 8-502
      of the UCC) may be asserted against such Underwriter with respect to such
      Securities.

            (b) Such Selling Stockholder has not taken, directly or indirectly,
      any action designed to or which has constituted or which might reasonably
      be expected to cause or result, under the Exchange Act or otherwise, in
      stabilization or manipulation of the price of any security of the Company
      to facilitate the sale or resale of the Securities.

            (c) Certificates in negotiable form for such Selling Stockholder's
      Securities have been or, prior to the Closing, will be placed in custody
      (which deposit may occur on the books of the Company's transfer agent
      without physical delivery of a certificate), for delivery pursuant to the
      terms of this Agreement, under a Custody Agreement and Power of Attorney
      duly authorized (if applicable) executed and delivered by such Selling
      Stockholder, in the form heretofore furnished to you (the "Custody
      Agreement") with ChaseMellon Shareholder Services, L.L.C., as Custodian
      (the "Custodian"); the Securities represented by the certificates so held
      in custody for each Selling Stockholder are subject to the interests
      hereunder of the Underwriters; the arrangements for custody and delivery
      of such certificates, made by such Selling Stockholder hereunder and under
      the Custody Agreement, are not subject to termination by any acts of such
      Selling Stockholder, or by operation of law, whether by the death or
      incapacity of such Selling Stockholder or the occurrence of any other
      event; and if any such death, incapacity or any other such event shall
      occur before the delivery of such Securities hereunder, certificates for
      the Securities will be delivered by the Custodian in accordance with the
      terms and conditions of this Agreement and the Custody Agreement as if
      such death, incapacity or other event had not occurred, regardless of
      whether or not the Custodian shall have received notice of such death,
      incapacity or other event.

            (d) No consent, approval, authorization or order of any court or
      governmental agency or body is required for the consummation by such
      Selling Stockholder of the transactions contemplated herein, except such
      as may have been obtained under the Act and such as may be required under
      the blue sky laws of any jurisdiction in connection with the purchase and
      distribution of the Securities by the Underwriters and such other
      approvals as have been obtained.


                                       13


            (e) Neither the sale of the Securities being sold by such Selling
      Stockholder nor the consummation of any other of the transactions herein
      contemplated by such Selling Stockholder or the fulfillment of the terms
      hereof by such Selling Stockholder will conflict with, result in a breach
      or violation of, or constitute a default under any law or the charter or
      by-laws of such Selling Stockholder or the terms of any indenture or other
      agreement or instrument to which such Selling Stockholder or any of its
      subsidiaries is a party or bound, or any judgment, order or decree
      applicable to such Selling Stockholder or any of its subsidiaries of any
      court, regulatory body, administrative agency, governmental body or
      arbitrator having jurisdiction over such Selling Stockholder or any of its
      subsidiaries.

            (f) Such Selling Stockholder has no reason to believe that the
      representations and warranties of the Company contained in this Section 1
      are not true and correct, is familiar with the Registration Statement and
      has no knowledge of any material fact, condition or information not
      disclosed in the Final Prospectus or any supplement thereto which has
      adversely affected or may adversely affect the business of the Company or
      any of its subsidiaries; and the sale of Securities by such Selling
      Stockholder pursuant hereto is not prompted by any information concerning
      the Company or any of its subsidiaries which is not set forth in the Final
      Prospectus or any supplement thereto.

            (g) In respect of any statements in or omissions from the
      Registration Statement or the Final Prospectus or any supplements thereto
      made in reliance upon and in conformity with information furnished in
      writing to the Company by any Selling Stockholder specifically for use in
      connection with the preparation thereof, such Selling Stockholder hereby
      makes the same representations and warranties to each Underwriter as the
      Company makes to such Underwriter under paragraph (i)(b) of this Section.

      Any certificate by any Selling Stockholder or any officer of any Selling
Stockholder and delivered to the Representatives or counsel for the Underwriters
in connection with the offering of the Securities shall be deemed a
representation and warranty by such Selling Stockholder, as to matters covered
thereby, to each Underwriter.

      2. Purchase and Sale.

            (a) Subject to the terms and conditions and in reliance upon the
      representations and warranties herein set forth, the Selling Stockholders
      agree, severally and not jointly, to sell to each Underwriter, and each


                                       14


      Underwriter agrees, severally and not jointly, to purchase from the
      Selling Stockholders, at a purchase price of $37.8575 per share, the
      amount of the Underwritten Securities set forth opposite such
      Underwriter's name in Schedule II hereto.

            (b) Subject to the terms and conditions and in reliance upon the
      representations and warranties herein set forth, the Selling Stockholders
      named in Schedule I hereby grant an option to the several Underwriters to
      purchase, severally and not jointly, up to 734,250 Option Securities at
      the same purchase price per share as the Underwriters shall pay for the
      Underwritten Securities. Said option may be exercised only to cover
      over-allotments in the sale of the Underwritten Securities by the
      Underwriters. Said option may be exercised in whole or in part at any time
      (but not more than once) on or before the 30th day after the date of the
      Final Prospectus upon written or telegraphic notice by the Representatives
      to the Company and such Selling Stockholders setting forth the number of
      shares of the Option Securities as to which the several Underwriters are
      exercising the option and the settlement date. The maximum number of
      Option Securities which each Selling Stockholder agrees to sell is set
      forth in Schedule I hereto. In the event that the Underwriters exercise
      less than their full over-allotment option, the number of Option
      Securities to be sold by each Selling Stockholder listed on Schedule I
      shall be, as nearly as practicable, in the same proportion as the maximum
      number of Option Securities to be sold by each Selling Stockholder and the
      number of Option Securities to be sold. The number of Option Securities to
      be purchased by each Underwriter shall be the same percentage of the total
      number of shares of the Option Securities to be purchased by the several
      Underwriters as such Underwriter is purchasing of the Underwritten
      Securities, subject to such adjustments as you in your absolute discretion
      shall make to eliminate any fractional shares.

      3. Delivery and Payment. Delivery of and payment for the Underwritten
Securities and the Option Securities (if the option provided for in Section 2(b)
hereof shall have been exercised on or before the third Business Day prior to
the Closing Date) shall be made at 9:00 A.M., New York City time, on November
17, 1999, or at such time on such later date not more than three Business Days
after the foregoing date as the Representatives shall designate, which date and
time may be postponed by agreement among the Representatives and the Selling
Stockholders or as provided in Section 9 hereof (such date and time of delivery
and payment for the Securities being herein called the "Closing Date"). Delivery
of the Securities shall be made to the Representatives for the respective
accounts of the several Underwriters against payment by the several Underwriters
through the Representatives of the respective aggregate purchase prices of the
Securities being sold by each of the Selling Stockholders to or upon the order
of the Selling Stockholders by wire transfer


                                       15


payable in same-day funds to the account specified by the Company and the
Selling Stockholders. Delivery of the Underwritten Securities and the Option
Securities shall be made through the facilities of The Depository Trust Company
unless the Representatives shall otherwise instruct.

      Each Selling Stockholder will pay all applicable state transfer taxes, if
any, involved in the transfer to the several Underwriters of the Securities to
be purchased by them from such Selling Stockholder and the respective
Underwriters will pay any additional stock transfer taxes involved in further
transfers.

      If the option provided for in Section 2(b) hereof is exercised after the
third Business Day prior to the Closing Date, the Selling Stockholders named in
Schedule I hereto will deliver the Option Securities (at the expense of the
Company) to the Representatives, at 388 Greenwich Street, New York, New York, on
the date specified by the Representatives (which shall be within three Business
Days after exercise of said option) for the respective accounts of the several
Underwriters, against payment by the several Underwriters through the
Representatives of the purchase price thereof to or upon the order of the
Selling Stockholders named in Schedule I by wire transfer payable in same-day
funds to the accounts specified by the Selling Stockholders named in Schedule I
hereto. If settlement for the Option Securities occurs after the Closing Date,
such Selling Stockholders will deliver to the Representatives on the settlement
date for the Option Securities, and the obligation of the Underwriters to
purchase the Option Securities shall be conditioned upon receipt of,
supplemental opinions, certificates and letters confirming as of such date the
opinions, certificates and letters delivered on the Closing Date pursuant to
Section 6 hereof.

      4. Offering by Underwriters. It is understood that the several
Underwriters propose to offer the Securities for sale to the public as set forth
in the Final Prospectus. Each of the Underwriters represents and agrees that (i)
it has not offered or sold and will not offer or sell any Securities to persons
in the United Kingdom except to persons whose ordinary activities involve them
in acquiring, holding, managing or disposing of investments (as principal or
agent) for the purposes of their businesses or otherwise in circumstances which
have not resulted and will not result in an offer to the public in the United
Kingdom within the meaning of the Public Offers of Securities Regulations 1995,
(b) it has complied, and will comply, with all applicable provisions of the
Financial Services Act of 1986 of Great Britain with respect to anything done by
it in relation to the Securities in, from or otherwise involving the United
Kingdom, and (c) it has only issued or passed on and will only issue or pass on
in the United Kingdom any document received by it in connection with the
issuance of the Securities to a person who is of a kind described in Article
11(3) of the Financial Services Act 1986 (Investment Advertisements)


                                       16


(Exemptions) Order 1996 of Great Britain or is a person to whom the document may
otherwise lawfully be issued or passed on.

      5. Agreements.

      (i) The Company agrees with the several Underwriters that:

            (a) The Company will use its best efforts to cause the Registration
      Statement, if not effective at the Execution Time, and any amendment
      thereof, to become effective. Prior to the termination of the offering of
      the Securities, the Company will not file any amendment of the
      Registration Statement or supplement (including the Final Prospectus or
      any Preliminary Final Prospectus) to the Basic Prospectus or any Rule
      462(b) Registration Statement unless the Company has furnished you a copy
      for your review prior to filing and will not file any such proposed
      amendment or supplement without the prior consent of the Representatives,
      which consent shall not be unreasonably withheld, conditioned or delayed.
      Subject to the foregoing sentence, if the Registration Statement has
      become or becomes effective pursuant to Rule 430A, or filing of the Final
      Prospectus is otherwise required under Rule 424(b), the Company will cause
      the Final Prospectus, properly completed, and any supplement thereto to be
      filed with the Commission pursuant to the applicable paragraph of Rule
      424(b) within the time period prescribed and will provide evidence
      satisfactory to the Representatives of such timely filing. If necessary
      for the sale of the Securities, the Company will cause the Rule 462(b)
      Registration Statement, completed in compliance with the Act and the
      applicable rules and regulations thereunder, to be filed with the
      Commission pursuant to Rule 462(b) and will provide evidence satisfactory
      to the Representatives of such filing. The Company will promptly advise
      the Representatives (1) when the Registration Statement, if not effective
      at the Execution Time, shall have become effective, (2) when the Final
      Prospectus, and any supplement thereto, shall have been filed (if
      required) with the Commission pursuant to Rule 424(b) or when any Rule
      462(b) Registration Statement shall have been filed with the Commission,
      (3) when, prior to termination of the offering of the Securities, any
      amendment to the Registration Statement shall have been filed or become
      effective, (4) of any request by the Commission or its staff for any
      amendment of the Registration Statement, or any Rule 462(b) Registration
      Statement, or for any supplement to the Final Prospectus or for any
      additional information, (5) of the issuance by the Commission of any stop
      order suspending the effectiveness of the Registration Statement or the
      institution or threatening of any proceeding for that purpose and (6) of
      the receipt by the Company of any notification with respect to the
      suspension of the qualification of the Securities for sale in any
      jurisdiction or the institution or


                                       17


      threatening of any proceeding for such purpose. The Company will use its
      best efforts to prevent the issuance of any such stop order or the
      suspension of any such qualification and, if issued, to obtain as soon as
      possible the withdrawal thereof. Prior to the completion of the sale of
      the Securities by the Underwriters, the Company will not file any document
      under the Exchange Act that is incorporated by reference in the
      Registration Statement unless, prior to such proposed filing, the Company
      has furnished the Representatives with a copy of such document for their
      review and the Representatives have not reasonably objected to the filing
      of such document within a reasonable period of time. The Company will
      promptly advise the Representatives when any document filed under the
      Exchange Act that is incorporated by reference in the Registration
      Statement shall have been filed with the Commission.

            (b) If, at any time when a prospectus relating to the Securities is
      required to be delivered under the Act, any event occurs as a result of
      which the Final Prospectus as then amended or supplemented would include
      any untrue statement of a material fact or omit to state any material fact
      necessary to make the statements therein, in the light of the
      circumstances under which they were made, not misleading, or if it should
      be necessary to amend the Registration Statement or supplement the Final
      Prospectus to comply with the Act or the Exchange Act or the respective
      rules thereunder, the Company promptly will (1) notify the Representatives
      of such event, (2) prepare and file with the Commission, subject to the
      second sentence of paragraph (a) of this Section 5, an amendment or
      supplement which will correct such statement or omission or effect such
      compliance and (3) supply any supplemented Final Prospectus to you in such
      quantities as you may reasonably request.

            (c) In accordance with the requirements of the Exchange Act and the
      Act applicable to the Company, the Company will make generally available
      to its security holders and to the Representatives an earnings statement
      or statements of the Company and its subsidiaries which will satisfy the
      provisions of Section 11(a) of the Act and Rule 158 under the Act.

            (d) The Company will furnish to the Representatives and counsel for
      the Underwriters, without charge, signed copies of the Registration
      Statement (including exhibits thereto) which is filed in connection with
      the sale of the Securities, and to each other Underwriter a copy of the
      Registration Statement (without exhibits thereto) which is filed in
      connection with the sale of the Securities, and, so long as delivery of a
      prospectus by an Underwriter or dealer may be required by the Act, as many
      copies of each Preliminary Final Prospectus and the Final Prospectus and
      any supplement


                                       18


      thereto as the Representatives may reasonably request. The Company will
      pay the expenses of printing or other production of all documents relating
      to the offering.

            (e) The Company will arrange, if necessary, for the qualification of
      the Securities for sale under the laws of such jurisdictions as the
      Representatives may designate, will maintain such qualifications in effect
      so long as required for the distribution of the Securities and will pay
      any fee of the National Association of Securities Dealers, Inc., in
      connection with its review of the offering; provided that in no event
      shall the Company be obligated to qualify to do business in any
      jurisdiction where it is not now so qualified or to take any action that
      would subject it to service of process in suits, other than those arising
      out of the offering or sale of the Securities, in any jurisdiction where
      it is not now so subject. The Company will promptly advise the
      Representatives of the receipt by the Company of any notification with
      respect to the suspension of the qualification of the Securities for sale
      in any jurisdiction or the initiation or threatening of any proceeding for
      such purpose. The Company shall use its best efforts to prevent the
      issuance of any order suspending the qualification or exemption of the
      Securities under any state securities or Blue Sky laws, and, if at any
      time any state securities commission or any other regulatory authority
      shall issue an order suspending the qualification or exemption of the
      Securities under any state securities or Blue Sky laws, the Company shall
      use every reasonable effort to obtain the withdrawal or lifting of such
      order at the earliest possible time.

            (f) The Company will not, and the stockholders listed on Schedule IV
      hereto will not, without the prior written consent of Salomon Smith Barney
      Inc., offer, sell, contract to sell, pledge, or otherwise dispose of, (or
      enter into any transaction which is designed to, or might reasonably be
      expected to, result in the disposition (whether by actual disposition or
      effective economic disposition due to cash settlement or otherwise) by the
      Company or any affiliate of the Company or any person in privity with the
      Company or any affiliate of the Company) directly or indirectly, including
      the filing (or participation in the filing) of a registration statement
      with the Commission in respect of, or establish or increase a put
      equivalent position or liquidate or decrease a call equivalent position
      within the meaning of Section 16 of the Exchange Act, any other shares of
      Common Stock or any securities convertible into, or exercisable, or
      exchangeable for, shares of Common Stock, or publicly announce an
      intention to effect any such transaction, for a period of 90 days after
      the date of the Underwriting Agreement; provided, however, that the
      Company may (1) issue and sell Common Stock pursuant to any employee stock
      option plan, stock ownership plan or dividend reinvestment plan of the
      Company in effect at the Execution Time; (2) issue


                                       19


      Common Stock issuable upon the conversion of securities or the exercise of
      warrants outstanding at the Execution Time; and (3) issue and sell Common
      Stock and convertible subordinated notes to Bell Atlantic Investments Inc.
      pursuant to the terms of that certain securities purchase agreement, dated
      October 7, 1999; and provided, further that, each of the stockholders
      listed on Schedule IV hereto may (1) transfer up to 3,000 shares of Common
      Stock as bona fide gifts; (2) transfer shares of Common Stock to an
      affiliate, family member, partner or member of such stockholder if such
      transferee agrees to become subject to the terms of this Section 5(i)(h);
      (3) cause the Company to issue shares of Common Stock and convertible
      subordinated notes pursuant to the Securities Purchase Agreement, dated
      October 7, 1999, between the Company and Bell Atlantic Investments, Inc.;
      (4) if applicable to such stockholder, enter into certain forward purchase
      contracts with DECS Trust VI relating to shares of Common Stock; (5) with
      respect to Sherman Tuan, sell up to 150,000 shares of Common Stock; and
      (6) with respect to David Rand, pledge up to 250,000 shares of Common
      Stock to secure margin loans entered into by him.

            (g) The Company will not take, directly or indirectly, any action
      designed to or which has constituted or which might reasonably be expected
      to cause or result, under the Exchange Act or otherwise, in stabilization
      or manipulation of the price of any security of the Company to facilitate
      the sale or resale of the Securities.

            (h) The Company agrees to pay the costs and expenses relating to the
      following matters: (i) the preparation, printing or reproduction of the
      Registration Statement, the Preliminary Final Prospectus and the Final
      Prospectus and each amendment or supplement to any of them; (ii) the
      printing (or reproduction) and delivery (including postage, air freight
      charges and charges for counting and packaging) of such copies of the
      Registration Statement, the Preliminary Final Prospectus and the Final
      Prospectus and all amendments or supplements to any of them, as may, in
      each case, be reasonably requested for use in connection with the offering
      and sale of the Securities; (iii) the preparation, printing,
      authentication, issuance and delivery of certificates for the Securities,
      including any stamp or transfer taxes in connection with the Securities;
      (iv) the printing (or reproduction) and delivery of this Agreement, the
      Custody Agreement, any blue sky memorandum and all other agreements or
      documents printed (or reproduced) and delivered in connection with the
      offering of the Securities; (v) any registration or qualification of the
      Securities for offer and sale under the securities or blue sky laws of the
      several states (including filing fees and the reasonable fees and expenses
      of one counsel for the Underwriters relating to such registration and
      qualification); (vi) fees and expenses of the Custodian;


                                       20


      (vii) the transportation and other expenses incurred by or on behalf of
      Company representatives in connection with presentations to prospective
      purchasers of the Securities; (viii) the fees and expenses of the
      Company's accountants and the fees and expenses of counsel (including
      local and special counsel) for the Company; and (ix) all other costs and
      expenses incident to the performance by the Company of its obligations
      hereunder; provided, however, that, except as otherwise provided for
      herein, the Underwriters shall pay their own costs and expenses, including
      the fees of their counsel, any advertising expenses connected with any
      offers they may make.

            (i) The Company agrees to do and perform all things required to be
      done and performed by it under this Agreement that are within its control
      on or prior to or after the Closing Date, as applicable, and to use its
      best efforts to satisfy all conditions precedent on its part to the
      delivery of the Securities.

      (ii) Each Selling Stockholder agrees with the several Underwriters that;

            (a) Such Selling Stockholder will not, without the prior written
      consent of Salomon Smith Barney Inc. offer, sell, contract to sell, pledge
      or otherwise dispose of, (or enter into any transaction which is designed
      to, or might reasonably be expected to, result in the disposition (whether
      by actual disposition or effective economic disposition due to cash
      settlement or otherwise) by the Company or any affiliate of the Company or
      any person in privity with the Company or any affiliate of the Company)
      directly or indirectly, or file (or participate in the filing of) a
      registration statement with the Commission in respect of, or establish or
      increase a put equivalent position or liquidate or decrease a call
      equivalent position within the meaning of Section 16 of the Exchange Act
      with respect to, any shares of capital stock of the Company or any
      securities convertible into or exercisable or exchangeable for such
      capital stock, or publicly announce an intention to effect any such
      transaction, for a period of 90 days after the date of this Agreement;
      provided, that each Selling Stockholder may (1) transfer up to 3,000
      shares of Common Stock disposed of as bona fide gifts, (2) transfer shares
      of Common Stock to an affiliate, family member, partner or member of such
      stockholder if such transferee agrees to become subject to the terms of
      this Section 5(i)(h), (3) cause the Company to issue shares of Common
      Stock and convertible subordinated notes pursuant to the Securities
      Purchase Agreement, dated October 7, 1999, between the Company and Bell
      Atlantic Investments, Inc., and (4) if applicable to such stockholder,
      enter into certain forward purchase contracts with DECS Trust VI relating
      to shares of Common Stock.


                                       21


            (b) Such Selling Stockholder will not take any action designed to or
      which has constituted or which might reasonably be expected to cause or
      result, under the Exchange Act or otherwise, in stabilization or
      manipulation of the price of any security of the Company to facilitate the
      sale or resale of the Securities.

            (c) Such Selling Stockholder will advise you promptly, and if
      requested by you, will confirm such advice in writing, so long as delivery
      of a prospectus relating to the Securities by an underwriter or dealer may
      be required under the Act, of (i) any material change in the Company's
      condition (financial or otherwise), prospects, earnings, business or
      properties, (ii) any change in information in the Registration Statement
      or the Final Prospectus relating to such Selling Stockholder or (iii) any
      new material information relating to the Company or relating to any matter
      stated in the Final Prospectus which comes to the attention of such
      Selling Stockholder.

      6. Conditions to the Obligations of the Underwriters. The obligations of
the Underwriters to purchase the Underwritten Securities and the Option
Securities, as the case may be, shall be subject to the accuracy of the
representations and warranties on the part of the Company contained herein as of
the Execution Time, the Closing Date and any settlement date pursuant to Section
3 hereof, to the accuracy of the statements of the Company and the Selling
Stockholders made in any certificates pursuant to the provisions hereof, to the
performance by the Company and the Selling Stockholders of their respective
obligations hereunder and to the following additional conditions:

            (a) If the Registration Statement has not become effective prior to
      the Execution Time, unless the Representatives agree in writing to a later
      time, the Registration Statement will become effective not later than (i)
      6:00 PM New York City time, on the date of determination of the public
      offering price, if such determination occurred at or prior to 3:00 PM New
      York City time on such date or (ii) 9:30 AM on the Business Day following
      the day on which the public offering price was determined, if such
      determination occurred after 3:00 PM New York City time on such date; if
      filing of the Final Prospectus, or any supplement thereto, is required
      pursuant to Rule 424(b), the Final Prospectus, and any such supplement,
      will be filed in the manner and within the time period required by Rule
      424(b); and no stop order suspending the effectiveness of the Registration
      Statement shall have been issued and no proceedings for that purpose shall
      have been instituted or threatened.

            (b) The Company shall have requested and caused Arnold L. Wadler,
      General Counsel of the Company, to furnish to the Representatives


                                       22


      his opinion, dated the Closing Date and addressed to the Representatives,
      to the effect that:

                  i. each of the Company's Subsidiaries has been duly
      incorporated and is validly existing as a corporation in good standing
      under the laws of the jurisdiction in which it is chartered or organized,
      with full corporate power and authority to own or lease, as the case may
      be, and to operate, its properties and conduct its business as described
      in the Final Prospectus;

                  ii. all the outstanding shares of capital stock of the Company
      and each Subsidiary have been duly and validly authorized and issued and
      are fully paid and nonassessable, and, except as otherwise set forth in
      the Final Prospectus, all outstanding shares of capital stock of the
      Subsidiaries are owned by the Company either directly or through wholly
      owned subsidiaries free and clear of any security interest and, to the
      knowledge of such counsel, after due inquiry, any other security
      interests, claims, liens or encumbrances;

                  iii. the Company's authorized capitalization is as set forth
      in the Final Prospectus under the heading "Capitalization"; the holders of
      outstanding shares of capital stock of the Company are not entitled to
      preemptive or other rights to subscribe for the Securities; and, to such
      counsel's knowledge, except as set forth in the Final Prospectus, no
      options, warrants or other rights to purchase, agreements or other
      obligations to issue, or rights to convert any obligation into or exchange
      any securities for, shares of capital stock of or ownership interests in
      the Company are outstanding;

                  iv. to the knowledge of such counsel, without conducting a
      docket search, there is no pending or threatened action, suit or
      proceeding by or before any court or governmental agency, authority or
      body or any arbitrator involving the Company or any of its subsidiaries or
      its or their property that is not adequately disclosed in the Final
      Prospectus, except in each case for such proceedings that, if the subject
      of an unfavorable decision, ruling or finding would not, singly or in the
      aggregate, result in a material adverse change in the condition (financial
      or otherwise), prospects, earnings, business or properties of the Company
      and its subsidiaries, taken as a whole; and the statements in the Final
      Prospectus under the heading "Business--Legal Proceedings" fairly
      summarize the matters therein described;

                  v. neither the execution and delivery of this Agreement, the
      sale of the Securities nor the consummation of any other of the


                                       23


      transactions herein contemplated, nor the fulfillment of the terms hereof,
      will conflict with, result in a breach or violation of, or imposition of
      any lien, charge or encumbrance upon, any property or asset of the Company
      or its subsidiaries pursuant to (i) the charter or by-laws of the
      Company's subsidiaries, or (ii) the terms of any indenture, contract,
      lease, mortgage, deed of trust, note agreement, loan agreement or other
      agreement, obligation, condition, covenant or instrument to which the
      Company or any of its subsidiaries is a party or bound or to which its
      respective property is subject which is known to such counsel;

                  vi. the statements in the Final Prospectus under the captions
      "Risk Factors - The Heavy Regulation of the Telecommunications Industry
      May Limit the Development of Our Networks and Affect Our Competitive
      Position" and "Business-Regulation" to the extent that they discuss U.S.
      federal, state, and local telecommunications statutes and regulations or
      legal or governmental proceedings of the FCC and state and local
      governments with respect to telecommunications regulatory matters, fairly
      summarize the matters referred to therein in all material respects;

                  vii. neither the execution and delivery of this Agreement by
      the Company nor the performance by the Company of its obligations under
      this Agreement will violate the Communications Act or the State
      Telecommunications Laws; and

                  viii. to the knowledge of such counsel and except such as
      would not have a material adverse effect on the Company's or any
      subsidiary's ability to conduct their respective businesses as they are
      presently conducted, (A) the Company and its subsidiaries have in effect
      all the U.S. federal and state telecommunications regulatory licenses,
      permits, authorizations, consents, and approvals (hereinafter, "Licenses")
      required to conduct their respective businesses as presently conducted;
      (B) all such Licenses have been validly issued and are in full force and
      effect; (C) no determination has been made by the FCC or any State
      Regulatory Agency that the Company or any subsidiary is in violation of
      any such Licenses, and no proceeding is pending before any such agency in
      which any such violation has been alleged; and (D) no proceedings by the
      FCC or any State Regulatory Agency to revoke or restrict any such Licenses
      are pending or threatened. "Validly issued" as used in this paragraph
      means that the Licenses have been issued through the means of regular
      agency procedures applied in conformity with the applicable governing
      statute and prior agency practice and there is no legal basis under the
      applicable governing statute to conclude that the Company or any
      subsidiary cannot hold one or more of the Licenses as a matter of law.
      "Full force and effect" as used in this paragraph means (i) the


                                       24


      orders issuing the Licenses have become effective under the applicable
      governing statute, (ii) the Licenses contain no conditions, (iii) all
      conditions precedent set forth in the Licenses have been satisfied, and
      (iv) no stay of effectiveness has been issued.

            (c) The Company shall have requested and caused Paul, Weiss,
      Rifkind, Wharton & Garrison, counsel for the Company, to furnish to the
      Representatives its opinion, dated the Closing Date and addressed to the
      Representatives, to the effect that:

                  i. the Company and each of the Subsidiaries incorporated (in
      the case of a corporation) or organized (in the case of any other entity)
      under the laws of the States of Delaware or New York has been duly
      incorporated and is validly existing as a corporation in good standing
      under the laws of the State of Delaware or is a subsisting corporation in
      good standing under the laws of the State of New York, as applicable, with
      full corporate power and authority to own or lease, as the case may be,
      and to operate its properties and conduct its business as described in the
      Final Prospectus;

                  ii. such counsel has been advised orally by the staff of the
      Commission that the Registration Statement has become effective under the
      Act; any required filing of the Basic Prospectus, any Preliminary Final
      Prospectus and the Final Prospectus, and any supplements thereto, has been
      made pursuant to Rule 424(b); to the knowledge of such counsel, no stop
      order suspending the effectiveness of the Registration Statement has been
      issued, no proceedings for that purpose have been instituted or threatened
      by the Commission, and assuming that the statements made and/or
      incorporated in the Registration Statement and the Final Prospectus are
      complete and correct except those made under the caption "Description of
      Capital Stock" insofar as they relate to provisions of documents therein
      described, the Registration Statement and the Final Prospectus, as of
      their respective effective or issue dates, appear on their face to be
      appropriately responsive in all material respects to the applicable
      requirements of the Act and the rules and regulations of the Commission
      under the Act, except for the financial statements, and other financial
      and statistical information which are contained or incorporated by
      reference therein or omitted therefrom, as to which such counsel need
      express no opinion;

                  iii. this Agreement has been duly authorized, executed and
      delivered by the Company;


                                       25


                  iv. the statements set forth under the heading "Description of
      Capital Stock", insofar as such statements purport to summarize certain
      provisions of the Securities, provide a fair summary of such provisions;

                  v. to the extent that they constitute a summary of U.S.
      federal law and regulations, the statements in the Final Prospectus under
      the heading "Certain United States Federal Income Tax Considerations"
      fairly summarize the matters therein described in all material respects;

                  vi. the Company is not and, after giving effect to the
      offering and sale of the Securities and the application of the proceeds
      thereof as described in the Final Prospectus, will not be required to
      register as an "investment company" under the Investment Company Act;

                  vii. no consent, approval, authorization, filing with or order
      of any court or governmental agency or body under the Federal laws of the
      United States or the laws of the State of New York or under the General
      Corporation Law of the State of Delaware is required in connection with
      the due authorization, execution and delivery of this Agreement, or for
      the offering, sale or delivery of the Securities, except such as will be
      obtained, taken or made or such, as may be required under the blue sky or
      securities laws of any state or foreign jurisdiction or the NASD (as to
      which such counsel need not express any opinion) or such other approvals
      (specified in such opinion) as have been obtained (provided that such
      counsel need not express any opinion with respect to any consent,
      approval, authorization under the Communications Act of 1934, as amended,
      or any published rules, regulations or policies of the Federal
      Communications Commission (the "FCC") thereunder); and

                  viii. neither the execution and delivery of this Agreement,
      the sale of the Securities nor the consummation of any other of the
      transactions herein contemplated, nor the fulfillment of the terms hereof,
      will conflict with, result in a breach or violation of, or imposition of
      any lien, charge or encumbrance upon any property or asset of the Company
      or its subsidiaries pursuant to, (i) the charter or by-laws of the
      Company; or (ii) any statute, law, rule or regulation of the Federal
      government of the United States (excluding the FCC) or the State of New
      York or under the General Corporation Law of the State of Delaware, or to
      such counsel's knowledge, any judgment, order or decree applicable to the
      Company or any of its subsidiaries of any court, regulatory body,
      administrative agency, governmental body, arbitrator or other authority
      having jurisdiction over the


                                       26


      Company, any of its subsidiaries or any of their respective properties
      which is known to such counsel except as described in the Final Prospectus
      or for such violations as could not be reasonably expected to have, singly
      or in the aggregate, a material adverse effect on the condition (financial
      or otherwise), prospects, earnings, business or properties of the Company
      and its subsidiaries, taken as a whole.

      In addition, such counsel shall state that it has participated in
conferences with officers and other representatives of the Company,
representatives of the independent accountants of the Company, the Underwriters
and counsel for the Underwriters at which the contents of the Registration
Statement and the Final Prospectus and related matters were discussed and,
although such counsel is not passing upon, and does not assume any
responsibility for, the accuracy, completeness or fairness of the statements
contained in the Registration Statement and the Final Prospectus (or any
amendments or supplements thereto) and has made no independent investigation or
verification thereof, and such counsel has not participated in the preparation
of the Incorporated Documents, on the basis of the foregoing, no facts have come
to the attention of such counsel that have led such counsel to believe that the
Registration Statement, at the Effective Time, and the Final Prospectus, at the
Execution Time and on the Closing Date, contained or contains any untrue
statement of a material fact or omitted or omits to state any material fact
necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading (in each case, other than the
financial statements, schedules and other financial and statistical information
which are contained or incorporated by reference therein or omitted therefrom,
as to which such counsel need express no opinion).

            In rendering such opinion, such counsel may rely (A) as to matters
involving the application of laws of any jurisdiction other than the State of
New York, the Federal laws of the United States or the General Corporation Law
of the State of Delaware, to the extent they deem proper and specified in such
opinion, upon the opinion of other counsel of good standing whom they believe to
be reliable and who are reasonably satisfactory to counsel for the Underwriters;
and (B) as to matters of fact, to the extent they deem proper, on certificates
of responsible officers of the Company and public officials. References to the
Registration Statement and the Prospectus in this Section 6(c) include any
amendment or supplement thereto at the Closing Date.

            (d) The Company shall have furnished to the Representatives the
      opinion of Baker & McKenzie, special regulatory counsel for the Company,
      dated the Closing Date, to the effect that:


                                       27


                  i. to the extent they constitute a summary of the regulatory
      matters referred to therein, the statements in the Registration Statement
      and the Final Prospectus under the caption "Business--Regulation of
      International Operations" fairly summarize the matters referred to
      therein;

                  ii. no licenses under telecommunications legislation in
      England and Wales including the Telecommunications Act 1984, the Wireless
      Telegraphy Act 1949 or the Wireless Telegraphy Act 1998 other than the
      Licenses are required by the Company, ION LLC, ION or Racal to carry on
      the ION Business in the United Kingdom;

                  iii. no licenses under telecommunications legislation in
      England and Wales including the Telecommunications Act 1984, the Wireless
      Telegraphy Act 1949 or the Wireless Telegraphy Act 1998, other than the
      Licenses that are currently required by the Company in relation to the
      Company's telecommunications business as presently conducted in the United
      Kingdom; and

                  iv. no German telecommunications licenses, other than the
      class 3 license obtained by Metromedia Fiber Network GmbH, are currently
      required by the Company in relation to the European Network, the German
      Network, or the Company's telecommunications business as presently
      conducted in Germany.

            In rendering such opinion, such counsel may state that they express
no opinion as to the laws of any jurisdiction other than Germany or the United
Kingdom or the regulations of the European Union.

            (e) The Selling Stockholders shall have requested and caused Paul,
      Weiss, Rifkind, Wharton & Garrison, counsel for the Selling Stockholders,
      to have furnished to the Representatives their opinion dated the Closing
      Date and addressed to the Representatives, to the effect that:

                  i. this Agreement, the Custody Agreement and Power of Attorney
      have been duly authorized (with respect to any Selling Stockholder which
      is not a natural person), executed and delivered by the Selling
      Stockholders, the Custody Agreement is valid and binding on the Selling
      Stockholders and each Selling Stockholder has full legal right and
      authority to sell, transfer and deliver in the manner provided in this
      Agreement and the Custody Agreement the Securities being sold by such
      Selling Stockholder hereunder;


                                 28


                  ii. assuming that each Underwriter acquires its interest in
      the Securities it has purchased from such Selling Stockholder in good
      faith without notice of any adverse claim (within the meaning of Section
      8-105 of the UCC), each Underwriter that has purchased such Securities
      delivered on the Closing Date to The Depository Trust Company or other
      securities intermediary (assuming such are securities intermediaries
      within the meaning of Section 8-102(14) of the UCC) by making payment
      therefor as provided herein, and that has had such Securities credited by
      book entry to the securities account or accounts (within the meaning of
      Section 8-501(a) of the UCC) of such Underwriter maintained by The
      Depository Trust Company or such other securities intermediary will have
      acquired a security entitlement (within the meaning of Section
      8-102(a)(17) of the UCC) to such Securities purchased by such Underwriter,
      and no action based on an adverse claim (within the meaning of Section
      8-102(a)(1) and Section 8-502 of the UCC) may be asserted against such
      Underwriter with respect to such Securities;

                  iii. to such counsel's knowledge, no consent, approval,
      authorization or order of any court or governmental agency or body is
      required for the consummation by any Selling Stockholder of the
      transactions contemplated herein, except such as may have been obtained
      under the Act and such as may be required under the blue sky laws of any
      jurisdiction in connection with the purchase and distribution of the
      Securities by the Underwriters and such other approvals as have been
      obtained; and

                  iv. neither the sale of the Securities being sold by any
      Selling Stockholder nor the consummation of any other of the transactions
      herein contemplated by any Selling Stockholder or the fulfillment of the
      terms hereof by any Selling Stockholder will conflict with, result in a
      breach or violation of, or constitute a default under any statute, rule or
      regulation known by such counsel to be applicable to such Selling
      Stockholder or the charter or By-laws of the Selling Stockholder (with
      respect to any Selling Stockholder which is not a natural person) or the
      terms of any indenture or other agreement or instrument known to such
      counsel and to which the Selling Stockholder is a party or bound, or any
      judgment, order or decree known to such counsel to be applicable to the
      Selling Stockholder of any court, regulatory body, administrative agency,
      governmental body or arbitrator having jurisdiction over the Selling
      Stockholder.

            (f) The Representatives shall have received from Skadden, Arps,
      Slate, Meagher & Flom LLP, counsel for the Underwriters, such opinion or
      opinions, dated the Closing Date and addressed to the Representatives,
      with respect to the sale of the Securities, the Registration Statement,
      the Final Prospectus (together with any supplement thereto) and other
      related matters


                                       29


      as the Representatives may reasonably require, and the Company shall have
      furnished to such counsel such documents as they reasonably request for
      the purpose of enabling them to pass upon such matters.

            (g) The Company shall have furnished to the Representatives a
      certificate of the Company, signed by the Chairman of the Board of
      Directors or the President and the principal financial or accounting
      officer of the Company, dated the Closing Date, to the effect that the
      signers of such certificate have carefully examined the Registration
      Statement, the Final Prospectus, any supplements to the Final Prospectus
      and this Agreement and that:

                  i. the representations and warranties of the Company in this
      Agreement are true and correct in all material respects on and as of the
      Closing Date with the same effect as if made on the Closing Date, and the
      Company has complied with all the agreements and satisfied all the
      conditions on its part to be performed or satisfied hereunder at or prior
      to the Closing Date;

                  ii. no stop order suspending the effectiveness of the
      Registration Statement has been issued and no proceedings for that purpose
      have been instituted or, to the Company's knowledge, threatened; and

                  iii. since the date of the most recent financial statements
      included or incorporated by reference in the Final Prospectus (exclusive
      of any amendment or supplement thereto), there has been no material
      adverse change in the condition (financial or otherwise), prospects,
      earnings, business or properties of the Company and its subsidiaries,
      taken as a whole, whether or not arising from transactions in the ordinary
      course of business, except as set forth in or contemplated in the Final
      Prospectus (exclusive of any amendment or supplement thereto).

            (h) Each Selling Stockholder shall have furnished to the
      Representatives a certificate, signed by such Selling Stockholder, dated
      the Closing Date, to the effect that the signers of such certificate have
      carefully examined the Registration Statement, the Final Prospectus, any
      supplement to the Final Prospectus and this Agreement and that the
      representations and warranties of such Selling Stockholder in this
      Agreement are true and correct in all material respects on and as of the
      Closing Date to the same effect as if made on the Closing Date.

            (i) At the Execution Time and at the Closing Date, the Company shall
      have requested and caused Ernst & Young LLP to furnish to the


                                       30


      Representatives letters, dated respectively as of the Execution Time and
      as of the Closing Date, in form and substance satisfactory to the
      Representatives, confirming that they are independent accountants within
      the meaning of the Act and the Exchange Act and the applicable rules and
      regulations thereunder, that they have performed a review of the unaudited
      interim financial information of the Company for the nine month period
      ended September 30, 1999 and as at September 30, 1999 and stating in
      effect that:

                  i. in their opinion the audited financial statements and
      financial statement schedules included or incorporated in the Registration
      Statement and the Final Prospectus and reported on by them comply as to
      form in all material respects with the applicable accounting requirements
      of the Exchange Act and the related published rules and regulations
      thereunder;

                  ii. on the basis of a reading of the latest unaudited
      financial statements made available by the Company and its subsidiaries;
      their limited review in accordance with the standards established under
      Statement on Auditing Standards No. 71, of the unaudited interim financial
      information for the nine month period ended September 30, 1999, and as at
      September 30, 1999; carrying out certain specified procedures (but not an
      examination in accordance with generally accepted auditing standards)
      which would not necessarily reveal matters of significance with respect to
      the comments set forth in such letter; a reading of the minutes of the
      meetings of the stockholders, directors and committees of the Company and
      the Subsidiaries; and inquiries of certain officials of the Company who
      have responsibility for financial and accounting matters of the Company
      and its subsidiaries as to transactions and events subsequent to December
      31, 1998, nothing came to their attention which caused them to believe
      that:

                  (1) any unaudited financial statements included or
            incorporated in the Registration Statement and the Final Prospectus
            do not comply in form in all material respects with applicable
            accounting requirements and with the published rules and regulations
            of the Commission with respect to financial statements included or
            incorporated in quarterly reports on Form 10-Q under the Exchange
            Act; or that said unaudited financial statements are not in
            conformity with generally accepted accounting principles applied on
            a basis substantially consistent with that of the audited financial
            statements included or incorporated in the Registration Statement
            and the Final Prospectus;

                  (2) with respect to the period subsequent to September 30,
            1999, there were any changes, at a specified date not more than
            three


                                       31


            days prior to the date of the letter, in the capital stock, increase
            in long-term debt of the Company and its subsidiaries or
            stockholders' equity of the Company as compared with the amounts
            shown on the September 30, 1999 consolidated balance sheet included
            in the Final Prospectus, or for the period from October 1, 1999 to
            such specified date there were any decreases, as compared with the
            corresponding period in the preceding year in revenues of the
            Company and its subsidiaries, except in all instances for changes or
            decreases set forth in such letter, in which case the letter shall
            be accompanied by an explanation by the Company as to the
            significance thereof unless said explanation is not deemed necessary
            by the Representatives; or

                  (3) the information included under the headings "Selected
            Consolidated Financial Data" and "Management-Executive Compensation"
            is not in conformity with the disclosure requirements of Regulation
            S-K;

                  iii. they have performed certain other specified procedures as
      a result of which they determined that certain information of an
      accounting, financial or statistical nature (which is limited to
      accounting, financial or statistical information derived from the general
      accounting records of the Company and its subsidiaries) set forth in the
      Final Prospectus, including the information set forth under the captions
      "Risk Factors", "Use of Proceeds", "Capitalization", "Selected
      Consolidated Financial Data", "Management's Discussion and Analysis of
      Financial Condition and Results of Operations", "Business", "Management",
      and "Certain Relationships and Related Transactions" in the Final
      Prospectus, the information included or incorporated in Items 1, 2, 6, 7
      and 11 of the Company's Annual Report on Form 10-K incorporated in the
      Final Prospectus and the information included in the "Management's
      Discussion and Analysis of Financial Condition and Results of Operations"
      included or incorporated in the Company's Quarterly Reports on Form 10-Q,
      incorporated in the Final Prospectus agrees with the accounting records of
      the Company and its subsidiaries, excluding any questions of legal
      interpretation; and

                  iv. on the basis of a reading of the unaudited pro forma
      financial statements included or incorporated by reference in the
      Registration Statement and the Final Prospectus (the "pro forma financial
      statements"); carrying out certain specified procedures; inquiries of
      certain officials of the Company and AboveNet Communications, Inc. who
      have responsibility for financial and accounting matters; and proving the
      arithmetic accuracy of the application of the pro forma adjustments to the
      historical amounts in the pro forma financial statements, nothing came to
      their attention which caused


                                       32


      them to believe that the pro forma financial statements do not comply as
      to form in all material respects with the applicable accounting
      requirements of Rule 11-02 of Regulation S-X or that the pro forma
      adjustments have not been properly applied to the historical amounts in
      the compilation of such statements.

            (j) [Intentionally Omitted]

            (k) At the Execution Time and at the Closing Date, Deloitte & Touche
      LLP shall have furnished to the Representatives letters, dated
      respectively as of the Execution Time and as of the Closing Date, in form
      and substance satisfactory to the Representatives, confirming that they
      are independent accountants within the meaning of the Act and the
      applicable rules and regulations thereunder, and stating in effect that:

                  i. in their opinion the audited financial statements and
      financial statement schedules included in the Registration Statement and
      the Final Prospectus and reported on by them comply in form in all
      material respects with the applicable accounting requirements of the Act
      and the related published rules and regulations; and

                  ii. they have performed certain other specified procedures as
      a result of which they determined that certain information of an
      accounting, financial or statistical nature (which is limited to
      accounting, financial or statistical information derived from the general
      accounting records of the Company and its subsidiaries) set forth in the
      Registration Statement and the Final Prospectus agrees with the accounting
      records of the Company and its subsidiaries, excluding any questions of
      legal interpretation.

            References to the Final Prospectus in this paragraph (k) include any
supplement thereto at the date of the letter.

            (l) At the Execution Time and at the Closing Date,
      PricewaterhouseCoopers LLP shall have furnished to the Representatives a
      letter or letters, dated respectively as of the Execution Time and as of
      the Closing Date, in form and substance satisfactory to the
      Representatives, confirming that they are independent accountants within
      the meaning of the Act and the applicable rules and regulations
      thereunder, and stating in effect that:

                  i. in their opinion the audited financial statements and
      financial statement schedules included in the Registration Statement and
      the Final Prospectus and reported on by them comply in form in all
      material


                                       33


      respects with the accounting requirements of the Act and the related
      published rules and regulations; and

                  ii. they have performed certain other specified procedures as
      a result of which they determined that certain information of an
      accounting, financial or statistical nature (which is limited to
      accounting, financial or statistical information derived from the general
      accounting records of the Company and its subsidiaries) set forth in the
      Registration Statement and the Final Prospectus agrees with the accounting
      records of the Company and its subsidiaries, excluding any questions of
      legal interpretation.

            References to the Final Prospectus in this paragraph (l) include any
supplement thereto at the date of the letter.

            (m) Subsequent to the Execution Time or, if earlier, the dates as of
      which information is given in the Registration Statement (exclusive of any
      amendment thereof) and the Final Prospectus (exclusive of any amendment or
      supplement thereto), there shall not have been (i) any change or decrease
      specified in the letter or letters referred to in paragraph (g) of this
      Section 6 or (ii) any change, or any development involving a prospective
      change, in or affecting the condition (financial or otherwise), prospects,
      earnings, business or properties of the Company and its subsidiaries,
      taken as a whole, whether or not arising from transactions in the ordinary
      course of business, except as set forth in or contemplated in the Final
      Prospectus (exclusive of any amendment or supplement thereto) the effect
      of which, in any case referred to in clause (i) or (ii) above, is, in the
      sole judgment of the Representatives, so material and adverse as to make
      it impractical or inadvisable to market the Securities as contemplated by
      the Registration Statement (exclusive of any amendment thereof) and the
      Final Prospectus (exclusive of any amendment or supplement thereto).

            (n) Subsequent to the Execution Time, there shall not have been any
      decrease in the rating of any of the Company's debt securities by any
      "nationally recognized statistical rating organization" (as defined for
      purposes of Rule 436(g) under the Act) or any notice given of any intended
      or potential decrease in any such rating or of a possible change in any
      such rating that does not indicate the direction of the possible change.

            (o) No stop order suspending the effectiveness of the Registration
      Statement shall have been issued and no proceedings for that purpose shall
      have been taken or, to the knowledge of the Company, shall be contemplated
      by the Commission at or prior to the Closing Date; (ii) there shall not
      have been any change in the capital stock of the Company nor any material


                                       34


      increase in the short-term or long-term debt of the Company (other than in
      the ordinary course of business) from that set forth or contemplated in
      the Registration Statement or the Final Prospectus (or any amendment or
      supplement thereto); (iii) there shall not have been, since the respective
      dates as of which information is given in the Registration Statement and
      the Final Prospectus (or any amendment or supplement thereto), except as
      may otherwise be stated in the Registration Statement and Final Prospectus
      (or any amendment or supplement thereto), any material adverse change in
      the condition (financial or other), business, prospects, properties, net
      worth or results of operations of the Company and the Subsidiaries taken
      as a whole; (iv) the Company and the Subsidiaries shall not have any
      liabilities or obligations, direct or contingent (whether or not in the
      ordinary course of business), that are material to the Company and the
      Subsidiaries, taken as a whole, other than those reflected in the
      Registration Statement or the Final Prospectus (or any amendment or
      supplement thereto); and (v) all the representations and warranties of the
      Company contained in this Agreement shall be true and correct on and as of
      the date hereof and on and as of the Closing Date as if made on and as of
      the Closing Date and you shall have received a certificate, dated the
      Closing Date and signed by the chief executive officer and the chief
      financial officer of the Company (or such other officers as are acceptable
      to you), to the effect set forth in this Section 6(o) hereof.

            (p) The Company shall not have failed at or prior to the Closing
      Date to have performed or complied with any of its agreements herein
      contained and required to be performed or complied with by it hereunder at
      or prior to the Closing Date.

            (q) At the Execution Time, each stockholder listed on Schedule IV
      shall have furnished to the Representatives a letter substantially in the
      form of Exhibit A hereto addressed to the Representatives.

            (r) Prior to the Closing Date, the Company and Selling Stockholders
      shall have furnished to the Representatives such further information,
      certificates and documents as the Representatives may reasonably request.

            (s) If any of the conditions specified in this Section 6 shall not
      have been fulfilled in all material respects when and as provided in this
      Agreement, or if any of the opinions and certificates mentioned above or
      elsewhere in this Agreement shall not be in all material respects
      reasonably satisfactory in form and substance to the Representatives and
      counsel for the Underwriters, this Agreement and all obligations of the
      Underwriters


                                       35


      hereunder may be cancelled at, or at any time prior to, the Closing Date
      by the Representatives. Notice of such cancellation shall be given to the
      Company in writing or by telephone or facsimile confirmed in writing.

            (t) The documents required to be delivered by this Section 6 will be
      delivered at the office of Paul, Weiss, Rifkind, Wharton & Garrison,
      counsel for the Company, 1285 Avenue of the Americas, New York, New York
      10019, on the Closing Date.

      7. Reimbursement of Underwriters' Expenses. If the sale of the Securities
provided for herein is not consummated because any condition to the obligations
of the Underwriters set forth in Section 6 hereof is not satisfied, because of
any termination pursuant to Section 10 hereof or because of any refusal,
inability or failure on the part of the Company or any Selling Stockholder to
perform any agreement herein or comply with any provision hereof other than by
reason of a default by any of the Underwriters, the Company will reimburse the
Underwriters severally through Salomon Smith Barney Inc. on demand for all
out-of-pocket expenses (including reasonable fees and disbursements of one
counsel) that shall have been incurred by them in connection with the proposed
purchase and sale of the Securities. If the Company is required to make any
payments to the Underwriters under this Section 7 because of any Selling
Stockholder's refusal, inability or failure to satisfy any condition to the
obligations of the Underwriters set forth in Section 6, the Selling Stockholders
pro rata in proportion to the percentage of Securities to be sold by each shall
reimburse the Company on demand for all amounts so paid.

      8. Indemnification and Contribution. (a) The Company agrees to indemnify
and hold harmless each Underwriter, the directors, officers, employees and
agents of each Underwriter and each person who controls any Underwriter within
the meaning of either the Act or the Exchange Act against any and all losses,
claims, damages or liabilities, joint or several, to which they or any of them
may become subject under the Act, the Exchange Act or other Federal or state
statutory law or regulation, at common law or otherwise, insofar as such losses,
claims, damages or liabilities (or actions in respect thereof) arise out of or
are based upon any untrue statement or alleged untrue statement of a material
fact contained in the registration statement for the registration of the
Securities as originally filed or in any amendment thereof, or in the Basic
Prospectus, any Preliminary Final Prospectus or the Final Prospectus, or in any
amendment thereof or supplement thereto, or arise out of or are based upon the
omission or alleged omission to state therein a material fact required to be
stated therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading, and agrees to
reimburse each such indemnified party, as incurred, for any legal or other
expenses reasonably incurred by them in connection with investigating or
defending any such loss, claim, damage, liability or action; provided, however,
that (i) the


                                       36


Company will not be liable in any such case to the extent that any such loss,
claim, damage or liability arises out of or is based upon any such untrue
statement or alleged untrue statement or omission or alleged omission made
therein in reliance upon and in conformity with written information furnished to
the Company by or on behalf of any Underwriter through the Representatives
specifically for inclusion therein and (ii) with respect to any untrue statement
or alleged untrue statement of, or omission or alleged omission to state, a
material fact made in any Preliminary Final Prospectus, the indemnity agreement
contained in this Section 8(a) shall not inure to the benefit of any Underwriter
(or any of the directors, officers, employees and agents of such Underwriter or
any controlling person of such Underwriter) from whom the person asserting any
such loss, claim, damage or liability purchased the Securities concerned, to the
extent that any such loss, claim, damage or liability of such Underwriter occurs
under the circumstances where it shall have been determined by a court of
competent jurisdiction (or appropriate arbitral proceeding) by final and
nonappealable judgment that (w) the Company had previously furnished copies of
the Final Prospectus to the Underwriters, (x) delivery of the Final Prospectus
was required by the Act or under this Agreement to be made to such person, (y)
the untrue statement or omission of a material fact contained in the Preliminary
Final Prospectus was corrected in the Final Prospectus and (z) there was not
sent or given to such person, at or prior to the written confirmation of the
sale of such Securities to such person, a copy of the Final Prospectus. This
indemnity agreement will be in addition to any liability which the Company may
otherwise have.

            (b) Each Selling Stockholder severally and not jointly agrees to
      indemnify and hold harmless the Company, each of its directors, each of
      its officers, employees, agents and each person who controls the Company
      within the meaning of either the Act or the Exchange Act, each
      Underwriter, the directors, officers, employees and agents of each
      Underwriter and each person who controls the Company or any Underwriter
      within the meaning of either the Act or the Exchange Act and each other
      Selling Stockholder, if any, to the same extent as the foregoing indemnity
      from the Company to each Underwriter, but only with reference to written
      information furnished to the Company by or on behalf of such Selling
      Stockholder specifically for inclusion in the documents referred to in the
      foregoing indemnity. This indemnity agreement will be in addition to any
      liability which any Selling Stockholder may otherwise have.

            (c) Each Underwriter severally and not jointly agrees to indemnify
      and hold harmless the Company, each of its directors, each of its officers
      who signs the Registration Statement, and each person who controls the
      Company within the meaning of either the Act or the Exchange Act and each
      Selling Stockholder, to the same extent as the foregoing indemnity to


                                       37


      each Underwriter, but only with reference to written information relating
      to such Underwriter furnished to the Company by or on behalf of such
      Underwriter through the Representatives specifically for inclusion in the
      documents referred to in the foregoing indemnity. This indemnity agreement
      will be in addition to any liability which any Underwriter may otherwise
      have. The Company and each Selling Stockholder acknowledge that the
      statements set forth in the last paragraph of the cover page regarding
      delivery of the Securities, the first paragraph on page S-3 related to
      stabilization, syndicate covering transactions and penalty bids and, under
      the heading "Underwriting" or "Plan of Distribution", (i) the list of
      Underwriters and their respective participation in the sale of the
      Securities, (ii) the sentences related to concessions and reallowances and
      (iii) the paragraph related to stabilization, syndicate covering
      transactions and penalty bids in any Preliminary Final Prospectus and the
      Final Prospectus constitute the only information furnished in writing by
      or on behalf of the several Underwriters for inclusion in any Preliminary
      Final Prospectus or the Final Prospectus.

            (d) Promptly after receipt by an indemnified party under this
      Section 8 of notice of the commencement of any action, such indemnified
      party will, if a claim in respect thereof is to be made against the
      indemnifying party under this Section 8, notify the indemnifying party in
      writing of the commencement thereof; but the failure so to notify the
      indemnifying party (i) will not relieve it from liability under paragraph
      (a), (b) or (c) above unless and to the extent it did not otherwise learn
      of such action and such failure results in the forfeiture by the
      indemnifying party of substantial rights and defenses as determined by a
      court of competent jurisdiction and (ii) will not, in any event, relieve
      the indemnifying party from any obligations to any indemnified party other
      than the indemnification obligation provided in paragraph (a), (b) or (c)
      above. The indemnifying party shall be entitled to assume the defense of
      such action and appoint counsel of the indemnifying party's choice at the
      indemnifying party's expense to represent the indemnified party in any
      action for which indemnification is sought (in which case the indemnifying
      party shall not thereafter be responsible for the fees and expenses of any
      separate counsel retained by the indemnified party or parties except as
      set forth below); provided, however, that such counsel shall be reasonably
      satisfactory to the indemnified party. Notwithstanding the indemnifying
      party's election to assume the defense of such action or appoint counsel
      to represent the indemnified party in an action, the indemnified party
      shall have the right to employ separate counsel (including local counsel),
      and the indemnifying party shall bear the reasonable fees, costs and
      expenses of such separate counsel if (i) the use of counsel chosen by the
      indemnifying party to represent the indemnified party would present such
      counsel with a conflict of interest, which has not been waived; (ii) the
      actual or potential


                                       38


      defendants in, or targets of, any such action include both the indemnified
      party and the indemnifying party and the indemnified party shall have been
      reasonably advised by such counsel that there are legal defenses available
      to it and/or other indemnified parties which are different from or
      additional to those available to the indemnifying party; (iii) the
      indemnifying party shall not have assumed the defense of the action or
      employed counsel reasonably satisfactory to the indemnified party to
      represent the indemnified party within a reasonable time after notice of
      the institution of such action; or (iv) the indemnifying party shall
      authorize the indemnified party to employ separate counsel at the expense
      of the indemnifying party. In any such case, the indemnifying party shall
      not, in connection with any one action or separate but substantially
      similar related actions in the same jurisdiction arising out of the same
      general allegations or circumstances, be liable for the fees and expenses
      of more than one separate firm of attorneys (in addition to any local
      counsel) for all indemnified parties. An indemnifying party will not,
      without the prior written consent of the indemnified parties, settle or
      compromise or consent to the entry of any judgment with respect to any
      pending or threatened claim, action, suit or proceeding in respect of
      which indemnification or contribution may be sought hereunder (whether or
      not the indemnified parties are actual or potential parties to such claim
      or action) unless such settlement, compromise or consent includes an
      unconditional release of each indemnified party from all liability arising
      out of such claim, action, suit or proceeding.

            (e) In the event that the indemnity provided in paragraph (a), (b)
      or (c) of this Section 8 is unavailable to or insufficient to hold
      harmless an indemnified party for any reason, each party liable under
      paragraph (a), (b) or (c) above (each, for purposes of this paragraph (e),
      an "Indemnifying Party") agrees to contribute to the aggregate losses,
      claims, damages and liabilities (including legal or other expenses
      reasonably incurred in connection with investigating or defending same)
      (collectively "Losses") to which such indemnified party may be subject in
      such proportion as is appropriate to reflect the relative benefits
      received by the Company and by the Selling Stockholders on the one hand
      and by the Underwriters on the other from the offering of the Securities;
      provided, however, that in no case shall any Underwriter (except as may be
      provided in any agreement among Underwriters relating to the offering of
      the Securities) be responsible for any amount in excess of the
      underwriting discount or commission applicable to the Securities purchased
      by such Underwriter hereunder. If the allocation provided by the
      immediately preceding sentence is unavailable for any reason, each
      Indemnifying Party shall contribute in such proportion as is appropriate
      to reflect not only such relative benefits but also the relative fault of
      the Company, of the Selling Stockholders and of the Underwriters in


                                       39


      connection with the statements or omissions or alleged statements or
      omissions which resulted in such Losses as well as any other relevant
      equitable considerations. Benefits received by the Company and the Selling
      Stockholders shall be deemed to be equal to the total net proceeds from
      the offering (before deducting expenses) received by it, and benefits
      received by the Underwriters shall be deemed to be equal to the total
      underwriting discounts and commissions, in each case as set forth on the
      cover page of the Final Prospectus. Relative fault shall be determined by
      reference to, among other things, whether any untrue or any alleged untrue
      statement of a material fact or the omission or alleged omission to state
      a material fact relates to information provided by the Company and the
      Selling Stockholders on the one hand or the Underwriters on the other, the
      intent of the parties and their relative knowledge, access to information
      and opportunity to correct or prevent such untrue statement or omission or
      alleged untrue statement or omission. The Company, the Selling
      Stockholders and the Underwriters agree that it would not be just and
      equitable if contribution were determined by pro rata allocation or any
      other method of allocation which does not take account of the equitable
      considerations referred to above. Notwithstanding the provisions of this
      paragraph (e), no person guilty of fraudulent misrepresentation (within
      the meaning of Section 11(f) of the Act) shall be entitled to contribution
      from any person who was not guilty of such fraudulent misrepresentation.
      For purposes of this Section 8, each person who controls an Underwriter
      within the meaning of either the Act or the Exchange Act and each
      director, officer, employee and agent of an Underwriter shall have the
      same rights to contribution as such Underwriter, and each person who
      controls the Company within the meaning of either the Act or the Exchange
      Act and each officer of the Company who shall have signed the Registration
      Statement and each director of the Company shall have the same rights to
      contribution as the Company, subject in each case to the applicable terms
      and conditions of this paragraph (e).

            (f) The liability of each Selling Stockholder under such Selling
      Stockholder's representations and warranties contained in Section 1 hereof
      and under the indemnity and contribution agreements contained in this
      Section 8 shall be limited to an amount equal to the public offering price
      of the Securities sold by such Selling Stockholder to the Underwriters
      (net of underwriting discounts or commissions, but before deducting
      expenses). The Company and the Selling Stockholders may agree, as among
      themselves and without limiting the rights of the Underwriters under this
      Agreement, as to the respective amounts of such liability for which they
      each shall be responsible.


                                       40


      9. Default by an Underwriter. If any one or more Underwriters shall fail
to purchase and pay for any of the Securities agreed to be purchased by such
Underwriter or Underwriters hereunder and such failure to purchase shall
constitute a default in the performance of its or their obligations under this
Agreement, the remaining Underwriters shall be obligated severally to take up
and pay for (in the respective proportions which the amount of Securities set
forth opposite their names in Schedule II hereto bears to the aggregate amount
of Securities set forth opposite the names of all the remaining Underwriters)
the Securities which the defaulting Underwriter or Underwriters agreed but
failed to purchase; provided, however, that in the event that the aggregate
amount of Securities which the defaulting Underwriter or Underwriters agreed but
failed to purchase shall exceed 10% of the aggregate amount of Securities set
forth in Schedule II hereto, the remaining Underwriters shall have the right to
(i) make arrangements for the purchase of the Securities which such defaulting
Underwriter or Underwriters agreed but failed to purchase by other persons
satisfactory to the Selling Stockholder and the non-defaulting Underwriters,
and/or (ii) purchase all, but shall not be under any obligation to purchase any,
of the Securities, and if such nondefaulting Underwriters do not make such
arrangements and/or purchase all the Securities, this Agreement will terminate
without liability to any nondefaulting Underwriter, the Selling Stockholders or
the Company. In the event of a default by any Underwriter as set forth in this
Section 9, the Closing Date shall be postponed for such period, not exceeding
five Business Days, as the Representatives shall determine in order that the
required changes in the Registration Statement and the Final Prospectus or in
any other documents or arrangements may be effected. Nothing contained in this
Agreement shall relieve any defaulting Underwriter of its liability, if any, to
the Company, the Selling Stockholders or any nondefaulting Underwriter for
damages occasioned by its default hereunder.

      10. Termination. This Agreement shall be subject to termination in the
absolute discretion of the Representatives, by notice given to the Company prior
to delivery of and payment for the Securities, if at any time prior to such time
(i) trading in the Company's Common Stock shall have been suspended by the
Commission or the NASDAQ National Market or trading in securities generally on
the New York Stock Exchange or the NASDAQ National Market shall have been
suspended or limited or minimum prices shall have been established on such
Exchange or the NASDAQ National Market; (ii) a banking moratorium shall have
been declared either by Federal or New York State authorities; or (iii) there
shall have occurred any outbreak or escalation of hostilities, declaration by
the United States of a national emergency or war, or other calamity or crisis
the effect of which on financial markets is such as to make it, in the sole
judgment of the Representatives, impractical or inadvisable to proceed with the
offering or delivery of the Securities as contemplated by the Final Prospectus
(exclusive of any amendment or supplement thereto).


                                       41


      11. Representations and Indemnities to Survive. The respective agreements,
representations, warranties, indemnities and other statements of the Company or
its officers, of each Selling Stockholder and of the Underwriters set forth in
or made pursuant to this Agreement will remain in full force and effect,
regardless of any investigation made by or on behalf of any Underwriter, any
Selling Stockholder or the Company or any of the officers, directors, employees,
agents or controlling persons referred to in Section 8 hereof, and will survive
delivery of and payment for the Securities. The provisions of Sections 7 and 8
hereof shall survive the termination or cancellation of this Agreement.

      12. Notices. All communications hereunder will be in writing and effective
only on receipt, and, if sent to the Representatives, will be mailed, delivered
or telefaxed to Salomon Smith Barney Inc. General Counsel (fax no.: (212)
816-7912) and confirmed to the General Counsel, Salomon Smith Barney Inc., at
388 Greenwich Street, New York, New York, 10013, Attention: General Counsel; or,
if sent to the Company, will be mailed, delivered or telefaxed to Metromedia
Fiber Network Services, Inc. c/o Metromedia Fiber Network, Inc., One North
Lexington Avenue, White Plains, New York 10601, Attention: Chief Financial
Officer (fax no.: (914) 421-6777) and confirmed to it at Metromedia Company, One
Meadowlands Plaza, East Rutherford, New Jersey 07073-2137, Attention: General
Counsel (fax no.: (201) 531-2803) and 215 East 67th Street, New York, New York
10021, Attention: Executive Vice President (fax no.: (212) 606-4337); or if sent
to any Selling Stockholders, will be mailed, delivered or telefaxed and
confirmed to it at the address set forth in Schedule I hereto.

      13. Successors. This Agreement will inure to the benefit of and be binding
upon the parties hereto and their respective successors and the officers and
directors and controlling persons referred to in Section 8 hereof, and, except
as expressly set forth in Section 5(h) or Section 8 hereof, no other person will
have any right or obligation hereunder.

      14. Applicable Law. This Agreement will be governed by and construed in
accordance with the laws of the State of New York applicable to contracts made
and to be performed within the State of New York.

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

      16. Headings. The section headings used herein are for convenience only
and shall not affect the construction hereof.


                                       42


      17. Definitions. The terms which follow, when used in this Agreement,
shall have the meanings indicated.

      "Act" shall mean the Securities Act of 1933, as amended and the rules and
regulations of the Commission promulgated thereunder.

      "Basic Prospectus" shall mean the prospectus referred to in paragraph 1(a)
above contained in the Registration Statement at the Effective Date including
any Preliminary Final Prospectus.

      "Business Day" shall mean any day other than a Saturday, a Sunday or a
legal holiday or a day on which banking institutions or trust companies are
authorized or obligated by law to close in New York City.

      "Commission" shall mean the Securities and Exchange Commission.

      "Communications Act" shall mean the Communications Act of 1934, as amended
(including amendments made by the Telecommunications Act of 1996), 47 U.S.C.
section 151 and the rules and regulations of the FCC.

      "Effective Date" shall mean each date and time that the Registration
Statement, any post-effective amendment or amendments thereto and any Rule
462(b) Registration Statement became or become effective.

      "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended,
and the rules and regulations of the Commission promulgated thereunder.

      "Execution Time" shall mean the date and time that this Agreement is
executed and delivered by the parties hereto.

      "Final Prospectus" shall mean the prospectus supplement relating to the
Securities that was first filed pursuant to Rule 424(b) after the Execution
Time, together with the Basic Prospectus.

      "Preliminary Final Prospectus" shall mean any preliminary prospectus
supplement to the Basic Prospectus which describes the Securities and the
offering thereof and is used prior to filing of the Final Prospectus, together
with the Basic Prospectus.

      "Registration Statement" shall mean the registration statement referred to
in paragraph 1(a) above, including exhibits and financial statements, as amended
at the Execution Time (or, if not effective at the Execution Time, in the form
in which it shall become effective) and, in the event any post-effective
amendment thereto or


                                       43


any Rule 462(b) Registration Statement becomes effective prior to the Closing
Date, shall also mean such registration statement as so amended or such Rule
462(b) Registration Statement, as the case may be. Such term shall include any
Rule 430A Information deemed to be included therein at the Effective Date as
provided by Rule 430A.

      "Rule 415", "Rule 424", "Rule 430A" and "Rule 462" refer to such rules
under the Act.

      "Rule 430A Information" shall mean information with respect to the
Securities and the offering thereof permitted to be omitted from the
Registration Statement when it becomes effective pursuant to Rule 430A.

      "Rule 462(b) Registration Statement" shall mean a registration statement
and any amendments thereto filed pursuant to Rule 462(b) relating to the
offering covered by the registration statement referred to in Section 1(a)
hereof.

      "State Telecommunications Laws" shall mean the comparable state statutes
of all states in which the Company and/or its subsidiaries is certified to
provide services.


                                       44


      If the foregoing is in accordance with your understanding of our
agreement, please sign and return to us the enclosed duplicate hereof, whereupon
this Agreement and your acceptance shall represent a binding agreement among the
Company, the Selling Stockholders and the several Underwriters as of the date
written above.

                                        Very truly yours,
                                        METROMEDIA FIBER NETWORK, INC.


                                        By: /s/ Gerard Benedetto
                                            ------------------------------------
                                            Name: Gerard Benedetto
                                            Title: Chief Financial Officer and
                                                   Senior Vice President

[Underwriting Agreement-Secondary Offering]


                                        /s/ Stephen A. Garofalo
                                        ----------------------------------------
                                        STEPHEN A. GAROFALO


                                        /s/ Howard M. Finkelstein
                                        ----------------------------------------
                                        HOWARD M. FINKELSTEIN


                                        /s/ Gerard Benedetto
                                        ----------------------------------------
                                        GERARD BENEDETTO


                                        /s/ Silvia Kessel
                                        ----------------------------------------
                                        SILVIA KESSEL


                                        /s/ John W. Kluge
                                        ----------------------------------------
                                        JOHN W. KLUGE


                                        DR & DESCENDANTS, L.L.C.


                                        By: /s/ William L. Asmuundson
                                            ------------------------------------
                                            Name: William L. Asmundson
                                            Title: President & CEO


                                        /s/ Stuart Subotnick
                                        ----------------------------------------
                                        STUART SUBOTNICK


                                        /s/ Arnold L. Wadler
                                        ----------------------------------------
                                        ARNOLD L. WADLER

[Underwriting Agreement-Secondary Offering]


                                       46


The foregoing Agreement is hereby confirmed and accepted as of the date written
above.

Salomon Smith Barney Inc.
Credit Suisse First Boston Corporation
Deutsche Bank Securities Inc.
Donaldson Lufkin & Jenrette Securities Corporation
Goldman, Sachs & Co.
Merrill Lynch, Pierce, Fenner & Smith Incorporated

By: Salomon Smith Barney Inc.


      By: /s/ Robert Doherty
          ----------------------------------------
          Name: Robert Doherty
          Title: Director

          For themselves and the other
          several Underwriters, if any,
          named in Schedule II to the
          foregoing Agreement.

[Underwriting Agreement-Secondary Offering]


                                       47


                                   SCHEDULE I

 Selling Stockholders:   Number of Underwritten       Maximum Number of
                         Securities to be Sold   Option Securities to be Sold

Stephen A. Garofalo            1,156,000                   173,400
One North Lexington Ave.
White Plains, NY 10601

Howard M. Finkelstein          2,400,000                   360,000
One North Lexington Ave.
White Plains, NY 10601

Gerard Benedetto                 235,000                    35,250
One North Lexington Ave.
White Plains, NY 10601

Silvia Kessel                     96,000                    14,400
215 East 67th Street
New York, NY 10021

DR & Descendants, L.L.C.         170,000                    25,500
30 Rockefeller Plaza
New York, NY 10112

Stuart Subotnick                 575,000                    86,250
215 East 67th Street
New York, NY 10021

John Kluge                       143,000                    21,450
215 East 67th Street
New York, NY 10021

Arnold L. Wadler                 120,000                    18,000
One Meadowlands Plaza
East Rutherford, NJ 07073

Total ................         4,895,000                   734,250
                               =========                   =======


                                     1


                                   SCHEDULE II

          Underwriters              Number of Underwritten
          ------------            Securities to be Purchased
                                  --------------------------

Salomon Smith Barney Inc.                  2,447,500

Credit Suisse First Boston Corporation       979,000

Deutsche Bank Securities Inc.                979,000

Donaldson, Lufkin & Jenrette                 244,750
        Securities Corporation

Goldman, Sachs & Co.                         122,375

Merrill Lynch, Pierce, Fenner & Smith        122,375
Incorporated

Total                                      4,895,000


                                        1


                                  SCHEDULE III

Subsidiaries of the Company
- ---------------------------

1. Metromedia Fiber Network NYC, Inc.

2. Metromedia Fiber Network Services, Inc.

3. AboveNet Communications Inc.

4. Metromedia Fiber Network International, Inc.


                                        2


                                   SCHEDULE IV

Stockholders to provide Lock-Up Agreements
- ------------------------------------------

1. Vincent A. Galluccio

2. Nicholas M. Tanzi

3. David Rand

4. Sherman Tuan

5. Metromedia Company


                                        3


                                    Exhibit A

      [Letterhead of officer, director or major stockholder of Corporation]

                                        , 1999

Salomon Smith Barney Inc.
Credit Suisse First Boston Corporation
Deutsche Bank Securities Inc.
Donaldson Lufkin & Jenrette
   Securities Corporation
Goldman, Sachs & Co.
Merrill Lynch, Pierce, Fenner & Smith
             Incorporated

As Representatives of the several Underwriters,
c/o  Salomon Smith Barney Inc.
     388 Greenwich Street
     New York, New York 10013

Ladies and Gentlemen:

      This letter is being delivered to you in connection with the proposed
Underwriting Agreement (the "Underwriting Agreement"), between Metromedia Fiber
Network, Inc., a Delaware corporation (the "Company"), the Selling Stockholders
listed in Schedule I thereto and each of you as representatives of a group of
Underwriters named therein, relating to an underwritten public offering of
Common Stock, $.01 par value (the "Common Stock"), of the Company.

      In order to induce you and the other Underwriters to enter into the
Underwriting Agreement, the undersigned will not, without the prior written
consent of Salomon Smith Barney Inc., offer, sell, contract to sell, pledge or
otherwise dispose of, (or enter into any transaction which is designed to, or
might reasonably be expected to, result in the disposition (whether by actual
disposition or effective economic disposition due to cash settlement or
otherwise) by the Company or any affiliate of the Company or any person in
privity with the Company or any affiliate of the Company) directly or
indirectly, including the filing or participation in the filing of) a
registration statement with the Securities and Exchange Commission in respect
of, or establish or increase a put equivalent position or liquidate or decrease
a call equivalent position within the meaning of Section 16 of the Securities
Exchange Act of 1934, as amended, and the rules and regulations of the
Securities and Exchange Commission promulgated thereunder with respect to, any
shares of capital stock of the Company or any securities convertible into, or
exercisable or exchangeable for such capital stock, or publicly announce an
intention to effect any such


                                     4


transaction, for a period of 90 days after the date of this Agreement; provided,
however, that the undersigned may (i) transfer up to 3,000 shares of Common
Stock as bona fide gifts; (ii) transfer shares of Common Stock to an affiliate,
family member, partner or member of the undersigned if such transferee agrees to
become subject to the terms of this Agreement; (iii) cause the Company to issue
shares of Common Stock and convertible subordinated notes pursuant to the
Securities Purchase Agreement, dated October 7, 1999, between the Company and
Bell Atlantic Investments, Inc.; (iv) if applicable to the undersigned, enter
into certain forward purchase contracts with DECS Trust VI relating to shares of
Common Stock; (v) with respect to Sherman Tuan, sell up to 150,000 shares of
Common Stock; and (vi) with respect to David Rand, pledge up to 250,000 shares
of Common Stock to secure margin loans entered into by him.


                                        5


      If for any reason the Underwriting Agreement shall be terminated prior to
the Closing Date (as defined in the Underwriting Agreement), the agreement set
forth above shall likewise be terminated.

                                        Yours very truly,


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


                                        6