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                                                                 Exhibit 10.27.3

                       LEASE MODIFICATION AGREEMENT # 2

     This Lease Modification Agreement # 2  ("Agreement") dated this 11th day of
October, 1999, is by and between 290 Woodcliff Drive Company, a general
partnership organized and existing pursuant to the laws of the State of New York
with a principal office at c/o The Widewaters Group, Inc., P.O. Box 3, 5786
Widewaters Parkway, Dewitt, New York 13214-0003 ("Landlord"), and PaeTec
Communications, Inc., a corporation with a principal office at 290 Woodcliff
Drive, Fairport, New York 14450 ("Tenant").

                                WITNESSETH THAT:

     WHEREAS, Landlord and Tenant entered into a Standard Office Space Lease
dated as of July 10, 1998, modified by Lease Modification Agreement #1 dated
September 30, 1998 (collectively, the "Lease") relating to 19,130 leasable
square feet of office space in the Woodcliff III Office Building, located at 290
Woodcliff Drive, Fairport, New York;

     WHEREAS, the Lease shall expire on December 31, 1999;

     WHEREAS, Landlord and Tenant have agreed to extend the term of the Lease
for an additional twelve (12) months; and

     WHEREAS, as part of such extension of the term, Landlord and Tenant agree
to modify and amend the Lease in order to reflect the same and to reflect
certain other modifications as set forth herein.

     NOW THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and legal sufficiency of which is hereby
acknowledged, Landlord and Tenant hereby agree as follows:

1.   Capitalized terms not defined in this Agreement shall have the meaning
     ascribed to them in the Lease.

2.   The term of the Lease is hereby extended for a period of twelve (12) months
     commencing January 1, 2000, and expiring December 31, 2000 (said twelve-
     month period is hereinafter referred to as the "Extension Term"). The
     Extension Term shall be upon all the same terms and conditions as are
     contained in the Lease, except that the Fixed Monthly Rent shall be Twenty-
     two and 50/100 Dollars ($22.50) per leasable square foot of premises [i.e.
     Thirty-five Thousand Eight Hundred Sixty-eight and 75/000 Dollars
     ($35,868.75)], payable in advance and in accordance with Section 3.01 of
     the Lease.

3.   Landlord shall have the right to recapture all, or a portion, of the
     Premises (the "Recaptured Premises") by giving Tenant thirty (30) days
     prior written notice at any time after September 1, 2000 ("Right To
     Recapture"). If Landlord exercises its Right To Recapture, Tenant's rights
     to the Recaptured Premises under the Lease shall be cancelled and
     terminated effective as of the later of (i) the date set forth in
     Landlord's notice as the termination date, or (ii) thirty days after
     Tenant's receipt of the notice. If Landlord recaptures less than the entire
     Premises (a) the Fixed Monthly Rent shall be prorated on the basis of the
     number of leaseable square feet retained by Tenant in proportion to the
     number of leaseable square feet contained in the Premises before Landlord's
     exercise of its Right To Recapture, and (b) the Lease shall continue
     thereafter in full force and effect with respect to the portion of the
     Premises retained by Tenant, and (c) the parties shall execute an amendment
     of the Lease to provide for the reduction in square footage and Fixed
     Monthly Rent.

4.   This Agreement may be executed in one or more counterparts, any one or
     all of which constitute one document.

5.   Tenant hereby certifies to Landlord that as of the date hereof: (i) the
     Lease is in full force and effect; (ii) there currently exist no default by
     Landlord under the Lease, nor any condition which with the giving of notice
     or the passage of time, or both, would constitute a default under the Lease
     on the part of Landlord; (iii) Tenant has no existing set-offs,
     counterclaims or defenses against Landlord under the Lease; and (iv) the
     Lease as modified hereby contains the entire agreement between the parties
     hereto with respect to the Premises, the Lease and the Building.

6.   Tenant represents and warrants that it has taken all necessary corporate,
     partnership or other action necessary to execute and deliver this
     Agreement, and that this Agreement constitutes the legally binding
     obligation of Tenant enforceable in accordance with its terms. Tenant
     further represents and warrants that it has full and complete authority to
     enter into and execute this

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     Agreement and acknowledges that Landlord is relying upon Tenant's
     representation of its authority to execute this Agreement and Tenant shall
     save and hold Landlord harmless from any claims, or damages including
     reasonable attorneys' fees arising from Tenant's misrepresentation of its
     authority to enter into and execute this Agreement.

7.   The effective date of this Agreement for all purposes shall be upon its
     full execution and it shall not be binding unless and until executed on
     behalf of both parties hereof.

8.   As of the effective date, this Agreement shall be attached to and
     automatically be deemed a part of the Lease. Except as herein modified and
     amended, all other terms and conditions of the Lease are hereby ratified
     and shall continue in full force and effect.


IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease Modification
Agreement #2.

                                       LANDLORD:
                                       290 Woodcliff Drive Company


                                       By: /S/ Joseph R. Scuderi
                                           ---------------------------------
                                           Joseph R. Scuderi
                                           Member of the Executive Committee


                                       TENANT:
                                       PaeTec Communications, Inc.


                                       By: /s/ Arunas A. Chesonis
                                           ------------------------------
                                           Arunas A. Chesonis
                                           President and CEO

STATE OF NEW YORK  )
                   ) SS.:
COUNTY OF ONONDAGA )

On the 11th day of October in the year 1999, before me, the undersigned, a
Notary Public in and for said State, personally appeared Joseph R. Scuderi,
personally known to me or proved to me on the basis of satisfactory evidence to
be the individual whose name is subscribed to the within instrument and
acknowledged to me that he executed the same in his capacities, and that by his
signature(s) on the instrument, the individuals, or the person upon behalf of
which the individual acted, executed the instrument.

                                   /s/ Kelly Lynn Crabtree
                                   ------------------------------
                                   Notary Public
                                   KELLY LYNN CRABTREE
                                   Notary Public, State of New York
                                   Qualified in Onondaga Co.
                                        No. 01CA4861404
                                   My Commission Expires June 9, 2000


STATE OF NEW YORK  )
                   ) SS.:
COUNTY OF MONROE   )

On the 5th day of October in the year 1999, before me, the undersigned, a Notary
Public in and for said State, personally appeared Arunas A. Chesonis, personally
known to me or proved to me on the basis of satisfactory evidence to be the
individual(s) whose name(s) is/are subscribed to the within instrument and
acknowledged to me that he/she/they executed the same in his/her/their
capacity(ies), and that by his/her/their signature(s) on the instrument, the
individual(s), or the person upon behalf of which the individual(s) acted,
executed the instrument.


                                          /s/ Marcia A. Benwitz
                                          -------------------------------
                                          NOTARY PUBLIC
                                          MARCIA A. BENWITZ
                                          Notary Public, State of New York
                                                  Monroe County
                                          My Commissioin Expires Sept. 30, 1998


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