<PAGE>

                   THIRD AMENDMENT TO STOCKHOLDERS' AGREEMENT

          THIS THIRD AMENDMENT TO STOCKHOLDERS' AGREEMENT (this "Amendment") is
dated as of ____________ , 1998 and is made and entered into by and among the
undersigned parties.

                                     RECITALS

          The undersigned parties, constitute the "Majority Investors,"
"Majority Shareholders" and the "Company" under that certain Stockholders'
Agreement, dated as of September 25, 1996, and amended by that First Amendment
to Shareholders' Agreement dated as of August 29, 1997 and the Second Amendment
to Stockholder's Agreement dated January __, 1998 (the "Stockholders'
Agreement")

          The undersigned desire to amend the Stockholders' Agreement under
Section 5.3 thereof.

                                    AGREEMENT

     Therefore, for good and valuable consideration the receipt and sufficiency
of which are hereby acknowledged, the parties hereto hereby agree as follows:

     1.  CERTAIN DEFINED TERMS.  Unless otherwise expressly defined in this
Amendment, capitalized terms used in this Amendment have the respective meanings
assigned to them in the Stockholders' Agreement.

     2.  AMENDMENTS TO THE STOCKHOLDERS' AGREEMENT.  Effective as of the date
hereof, the Stockholders' Agreement is hereby amended as follows:

          a.   The definition of Employee Option, appearing in Section 1.1 of
     the Stockholders' Agreement is hereby amended in its entirety to read as
     follows:

          EMPLOYEE OPTION:  Any option to purchase Common Stock for cash which
          is granted by or with the approval of the Board of Directors or the
          Compensation Committee (to the extent such committee is authorized by
          the Board of Directors to grant such options) to any director,
          officer, employee or consultant of the Corporation or any subsidiary
          of the Corporation pursuant to either (i) the Corporation's 1993 Stock
          Option Plan or the Corporation's 1994 Stock Option Plan as in effect
          on the Closing Date, (ii) any other option plan adopted by the
          Corporation after the Closing Date with the prior approval of the
          Majority Investors, in each case as the same may be amended from time
          to time with the prior approval of the Majority Investors, or (iii)
          any stock option plan in the form approved by the Board of Directors
          for the issuance of Common Stock which shall not exceed 82,000 shares
          of Common Stock (as adjusted for stock splits, combinations,
          recapitalization, reorganizations and similar transactions) provided
          that the options granted pursuant to such plans shall not be issued
          with an exercise 

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          price per share of Common Stock less than the lesser of (a) $77 (as 
          adjusted for stock splits, combinations, recapitalizations, 
          reorganizations and other similar transactions) or (b) the Conversion
          Price at the time of issuance, without the consent of the Series B 
          Director.

          b.   Section 3.8(a)(iii) of the Stockholders' Agreement is amended by
     deleting the words "Compensation Committee" therein and inserting "Board of
     Directors or the Compensation Committee (to the extent such committee is
     authorized by the Board of Directors to grant such options)" in their
     place.

          c.   Section 3.8(a)(xi) of the Stockholders' Agreement is amended by
     deleting the words "Compensation Committee" where such words appear and
     inserting "Board of Directors" in their place.

          d.   Section 3.13 of the Stockholders' Agreement is amended in its
     entirety to read as follows:

               Section 3.13. AUDIT, COMPENSATION AND VALUATION COMMITTEES.
          Unless the Majority Investors otherwise agree, the Board of Directors
          shall have an audit committee (the "Audit Committee"), a compensation
          committee (the "Compensation Committee") and a valuation committee
          (the "Valuation Committee"), each of which shall have three members
          one of whom shall be the Series B Director, and at least one other of
          whom shall be a Disinterested Outside Director and, so long as the
          directors of the Company include directors designated pursuant to
          SECTION 3.1(a), one of the directors designated pursuant to SECTION
          3.1(a).  The Audit Committee will have the authority and
          responsibility for making recommendations to the Board of Directors
          for the selection, engagement or discharge of independent auditors,
          reviewing with the independent auditors the plan and results of the
          auditing engagement, reviewing the Company's systems of internal
          accounting controls, directing investigations in matters within the
          scope of its functions and performing any and all other such functions
          customarily performed by audit committees of public companies.  The
          Compensation Committee will have the authority and responsibility for
          making recommendations to the Board of Directors in respect of
          establishing and administering the stock, incentive and other employee
          benefit plans of the Company, establishing and changing the
          compensation of executive officers, approving or amending existing and
          proposed employment agreements between the Company and its executive
          officers and performing any and all other such functions customarily
          performed by compensation committees of public companies.  The
          Valuation Committee shall have the authority and responsibilities as
          described in the Series B Certificate of Designation.  None of the
          Audit Committee, Compensation Committee or Valuation Committee shall
          have the authority to exercise any powers of the Board of Directors
          except to the extent authorized by the Board of Directors pursuant to



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<PAGE>

          a resolution adopted with the concurrence of the Series B Director,
          or, if there is no Series B Director, the Series C Director, or, if
          there is no Series C Director, the Majority Investors.  The
          requirement of the Board of Directors to designate each of the Audit
          Committee, the Compensation Committee and the Valuation Committee as
          set forth in this SECTION 3.13 shall terminate on the earlier of the
          date on which (i) all of the shares of Senior Preferred Stock held by
          the Investors are converted into Common Stock of the Company or (ii)
          the Investors no longer hold any shares of Senior Preferred Stock.

          3.   REAFFIRMATION.  The undersigned parties acknowledge that the
Stockholder's Agreement, as amended hereby, remains in full force and effect and
is hereby ratified and affirmed.

     IN WITNESS WHEREOF, the undersigned have duly executed and delivered this
Third Amendment to Stockholders' Agreement as of the date first above written.

                              "Company"

                              NEXT GENERATION NETWORK, INC.



                              By:____________________________
                              Thomas M. Pugliese, Chief Executive Officer


                              "Majority Shareholders"



                              ___________________________________
                                      GERARD P. JOYCE


                              ___________________________________
                                      THOMAS P. PUGLIESE












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<PAGE>

                              "Majority Investors"

                              21ST CENTURY COMMUNICATIONS
                               PARTNERS, L.P.

                              By:  SANDLER INVESTMENT
                                   PARTNERS, L.P., General Partner

                              By:  SANDLER CAPITAL MANAGEMENT, General Partner

                              By:  MJDM MEDIA CORP.,  General Partner



                              By:  _________________________________
                                   President

                              21ST CENTURY COMMUNICATIONS T-E
                              PARTNERS, L.P.

                              By:  SANDLER INVESTMENT
                                   PARTNERS, L.P., General Partner

                              By:  SANDLER CAPITAL MANAGEMENT,
                                   General Partner

                              By:  MJDM MEDIA CORP., General Partner



                              By:  _________________________________
                                   President










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<PAGE>
                              21ST CENTURY COMMUNICATIONS
                              FOREIGN PARTNERS, L.P.

                              By:  SANDLER INVESTMENT
                                   PARTNERS, L.P., General Partner

                              By:  SANDLER CAPITAL
                                   MANAGEMENT, General Partner

                              By:  MJDM MEDIA CORP., a General Partner



                              By:  __________________________________
                              President


















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