Confidential
      Treatment Request by RCN Corporation

    


    FIRST
      AMENDMENT TO DARK FIBER IRU AGREEMENT

    


    This
      First Amendment to Dark Fiber IRU Agreement ("Amendment")
      is
      between MCImetro Access Transmission Services of Massachusetts, Inc.
("MCI”),
      as
      successor-in-interest to Metropolitan Fiber Systems/McCourt, Inc., and RCN
      Telecom Services, Inc. ("RCN”),as
      successor-in-interest to RCN Telecom Services of Massachusetts,
      Inc.

    


    WHEREAS,
      the predecessors of MCI and RCN entered into a Dark Fiber IRU Agreement dated
      May 8, 1997 (the "Agreement");
      and

    


    WHEREAS,
      pursuant to the Proposed Final Judgment, defined below, MCI and RCN have entered
      into an Amended and Restated Master IRU Agreement, as amended, for the
      Boston-Worcester Metropolitan Statistical Area, which is subject to approval
      by
      the United States Department of Justice, as described below (“DOJ
      IRU”);
      and

    


    WHEREAS,
      RCN must use some of the Dedicated Fibers and the WorldCom Laterals, as both
      are
      defined in the Agreement, in conjunction with the DOJ IRU; and

    


    WHEREAS,
      RCN hereby elects to renew the Agreement for five years pursuant to the option
      to extend, as set forth in Section 25.b. of the Agreement (“Renewal
      Term”);
      and

    


    WHEREAS,
      MCI has agreed to accept a one-time payment for such extension, which will
      include the Recurring Charges and Maintenance Costs;

    


    NOW
      THEREFORE,
      in
      consideration of the terms set forth in this Amendment, MCI and RCN agree as
      follows:

    


    1.    Definitions. 
      All capitalized terms not otherwise defined herein shall have the meanings
      ascribed to them by the Agreement or by the DOJ IRU.

    


    2.    Term.
       Section
      11 of the Agreement is revised to read as follows:

    


    11. 
      Term.
      The
      "Term" is hereby defined as being the period which commences on the date of
      this
      Agreement and which ends on January 1, 2012 unless earlier terminated pursuant
      to the terms of this Agreement.

    


    3.    Renewal
      Fee.
       In
      consideration for the extension of the Agreement for five (5) years, RCN hereby
      agrees to pay to MCI the sum of Ù
      ($Ù)
      as a
      one-time fee for the entire Renewal Term (“Renewal
      Fee”).
      The
      Renewal Fee shall also include the payment of RCN's obligations pursuant to
      Sections 18.b.(i) and (ii) of the Agreement for the Renewal Term, and RCN shall
      not have any additional obligation for Sections 18.b.(i) and (ii) beyond the
      Renewal Fee. The obligations in Section 18.b.(iii) of the Agreement shall remain
      part of the Agreement. The Renewal Fee shall be paid to MCI within thirty (30)
      days after the date of an invoice from MCI for such fee.

    


    4.    Limited
      Exception to Restrictions.
      Notwithstanding the restrictions set out in Sections 12, 14 and 18.a. of the
      Agreement, in addition to any permitted uses in the Agreement, RCN may use
      the
      Dedicated Fibers and WorldCom Laterals for the limited purpose of connecting
      RCN's network to the Dark Fiber Facilities, as defined in the DOJ IRU. Such
      use
      shall only encompass traffic originating from or terminating at the buildings
      set out in Exhibit A-1 of the DOJ IRU.

     

    
      
        	
                Ù

              	
                Certain
                  information on this page has been omitted and filed separately
                  with the
                  Securities and Exchange Commission.

              


      

       

    

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    Confidential
      Treatment Request by RCN Corporation

     

    5.    Effective
      Date of Amendment.
      This
      Amendment shall not become effective until all three of the following conditions
      are met: (a) the receipt of the Renewal Fee by MCI; (b) entry by the United
      States District Court of the proposed Final Judgment filed in United
      States v. Verizon Communications Inc. and MCI, Inc.,
      United
      States District Court for the District of Columbia, Case No. 1 :05CV02 103
      (the
“Proposed
      Final Judgment”);
      and
      (c) approval by the United States Department of Justice (“DOJ”)
      of RCN
      as the
      acquirer of the Divestiture Assets identified in the Proposed Final Judgment
      for
      the Portland, Boston-Worchester, and Richmond Metropolitan Statistical Areas
      (the “MSAs”).
      In
      the event that 5(a), above, occurs but that either 5(b) or 5(c), above, does
      not
      occur, then RCN shall have sixty (60) days from the date that the Court denies
      the Proposed Final Judgment or DOJ provides notice that it does not approve
      RCN
      as the acquirer of the Divestiture Assets in the MSAs, whichever is earlier,
      to
      pay Verizon an additional Ù
      ($Ù)
      (the
“Additional
      Renewal Fee”)
      to
      make this Amendment effective. If RCN fails to pay the Additional Renewal Fee
      within such time period but has paid the Renewal Fee to Verizon, then RCN shall
      have an additional twelve (12) months (the “Migration
      Period”)
      to use
      the Dedicated Fibers and WorldCom Laterals under the Agreement, and Verizon
      shall reimburse RCN the difference between the Renewal Fee paid by RCN and
      a
pro
      rata
      portion
      of the Renewal Fee plus the Additional Renewal Fee (the “Original
      Renewal Fee,”
which
      is Ù
      ($Ù))
      from
      January 1, 2007 until the end of the Migration Period. By way of example, if
      DOJ
      provides notice that it does not approve RCN as a purchaser of the Divestiture
      Assets for the MSAs on January 11, 2007, then RCN has until March 12, 2007
      to
      pay the Additional Renewal Fee. If RCN does not pay the Additional Renewal
      Fee
      but has paid the Renewal Fee, then the Migration Period will end on March 12,
      2008 and Verizon will reimburse RCN $Ù,
      which
      is the Renewal Fee paid by RCN ($Ù)
      minus
      the pro rata portion of the Original Renewal Fee (the pro
      rata
      portion
      being $Ù,
      which
      is calculated as follows:
      $Ù
      (Original Renewal Fee) divided by 5 years, further divided by 365 days, then
      multiplied by 436 days (the period from January 1, 2007 to the end of the
      Migration Period)). At the end of the Migration Period (if applicable), RCN
      shall not have any rights to use nor any rights related to or associated with
      the Dedicated Fibers and WorldCom Laterals under the Agreement.

    


    6.    Savings
      Provision.
      Except
      as expressly provided herein, the Agreement shall

    remain
      in
      full force and effect as originally written.

    


    7.    Notices.
      The
      notices required or permitted by the Agreement shall be delivered in accordance
      with the provisions of Section 31of the Agreement to the following address(es)
      or such other addresses as the applicable party may specify by notice provided
      in accordance with Section 31 of the Agreement:

    


    
      	 	
              If
                to MCI: 

            	
              MCImetro
                Access Transmission

            
	 	 	
              Services
                of Massachusetts, Inc.

            
	 	 	
              Attn:
                Group Manager

            
	 	 	
              Department
                63353/107

            
	 	 	
              2400
                N. Glenville Dr.

            
	 	 	
              Richardson,
                TX 75082

            


    

     

    
      
        	
                Ù

              	
                Certain
                  information on this page has been omitted and filed separately
                  with the
                  Securities and Exchange
                  Commission.

              


      

    

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    Confidential
      Treatment Request by RCN Corporation

     

    
      	 	
              with
                a copy to:

            	
              MCImetro
                Access Transmission

            
	 	 	
              Services
                of Massachusetts, Inc.

            
	 	 	
              Attn:
                Legal Department

            
	 	 	
              2400
                N. Glenville Dr.

            
	 	 	
              Richardson,
                TX 75082

            
	 	 	 
	 	 	 
	 	
              If
                to RCN:

            	
              RCN
                Telecom Services

            
	 	 	
              196
                Van Buren Street

            
	 	 	
              Herndon,
                VA 20170

            
	 	 	
              ATTN:

            
	 	 	 
	 	 	 
	 	
              with
                a copy to: 

            	
              RCN
                Telecom Services

            
	 	 	
              196
                Van Buren Street

            
	 	 	
              Herndon,
                VA 20170

            
	 	 	
              ATTN:
                General Counsel

            


    

    


    


    8.    Counterparts.
      This
      Amendment may be executed in one or more counterparts, each of which shall
      be
      deemed an original, but all of which shall constitute the same
      instrument.

    


    IN
      WITNESS WHEREOF, the parties have caused this Amendment to be executed as of
      the
      date first set forth above by their duly authorized
      representatives.

     

    
      	
              MCImetro
                ACCESS TRANSMISSION 

              SERVICES
                OF MASSACHUSETTS, INC.

            	 	
              RCN
                TELECOM SERVICES, INC.

            
	 	 	 	 	 
	
              Name:

            	
              Joseph
                C. Cook

            	 	
              Name:

            	
              Michael
                T. Sicoli

            
	
              Title:

            	
              Vice
                President

            	 	
              Title:

            	
              EVP
                & CFO

            
	
              Date:
                

            	
              November
                28, 2006

            	 	
              Date:

            	
              November
                27, 2006