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                                                                   EXHIBIT 10.45

                           ELEVENTH AMENDMENT TO LEASE


        THIS ELEVENTH AMENDMENT OF LEASE (this "Amendment") is made and entered
into as of this 19th day of July, 2000, by and between REGIONAL INDUSTRIAL
DEVELOPMENT CORPORATION OF SOUTHWESTERN PENNSYLVANIA ("Landlord") and TOLLGRADE
COMMUNICATIONS, INC. ("Tenant").

WITNESSETH THAT:

        WHEREAS, Landlord and Tenant entered into a Lease Agreement dated August
5, 1993 (the "Original Lease"), as subsequently amended by the First, Second,
Third, Fourth, Fifth, Sixth, Seventh, Eighth, Ninth and Tenth Amendments to
Lease (collectively, with the Original Lease, referred to hereinafter as the
"Lease"); and

        WHEREAS, the parties desire to further amend the Lease in accordance
with the terms of this Amendment.

        NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, and intending to be legally bound
hereby, Landlord and Tenant covenant and agree as follows:

        1. The Landlord additionally leases and demised unto Tenant Seven
Thousand Two Hundred (7,200) square feet of space in the Complex, referred to as
Units 12A and 13A, for the period commencing July 1, 2000, and continuing
throughout the Term of the Lease, which space is more fully shown on Exhibit "A"
attached hereto and made a part hereof (herein referred to as the "Additional
Space"). The Additional Space shall be deemed hereafter to be part of the
Premises. Delivery of the Additional Space to Tenant shall be in "as is"
condition and compliance with all provisions of the Lease (except payment of
rental, as specified in Section 2 below, and except that Section 33 of the
Original Lease (HVAC System) shall not apply to the additional space) shall be
deemed to have taken place on July 1, 2000.

        2. As rental for the Additional Space, Tenant shall pay to Landlord as
Base Rent in advance beginning on July 1, 2000, and on the first business day of
each successive calendar month during the Term of the Lease, together with any
Additional Rent escalations as provided under the Lease, the following sums:

        For the period July 1, 2000, through December 31, 2000, the sum of Three
Thousand Two Hundred and Forty Dollars and No Cents ($3,240.00); and

        For the period January 1, 2001, through December 31, 2002, the sum of
Three Thousand Three Hundred and Sixty Dollars and No Cents ($3,360.00).

        3. In the event the Lease is renewed for the additional three year term
following expiration of the Lease, as provided in Section 4 of the Ninth
Amendment of Lease as subsequently amended in the Tenth Amendment of Lease,
Tenant shall pay to Landlord as Base Rent during such period,



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together with any Additional Rent escalations as provided under the Lease, the
following sums for the Additional Space:

        For the period January 1, 2003, through December 31, 2003, the sum of
Three Thousand Four Hundred and Sixty Two Dollars and No Cents ($3,462.00);

        For the period January 1, 2004, through December 31, 2004, the sum of
Three Thousand Five Hundred and Sixty Four Dollars and No Cents ($3,564.00); and

        For the period January 1, 2005, through December 31, 2005, the sum of
Three Thousand Six Hundred and Seventy Two Dollars and No Cents ($3,672.00).

Such sums shall be in addition to the amounts specified in the Tenth Amendment
to Lease for Base Rent for the Premises during such renewal period.

        4. Landlord promptly shall cause to be conducted repairs to the roof of
the Additional Space, in accordance with that certain Agreement between Landlord
and Bums & Scalo Roofing Company, Inc., made as of July 5, 2000, a copy of which
is attached hereto as Exhibit "B" and made a part hereof (the "Roof Repair
Agreement"), and such further change orders thereto as shall be acceptable to
both Landlord and Tenant ("Change Orders"). Upon completion of the roof repairs
in accordance with the Roof Repair Agreement and any Change Orders, Tenant shall
remit to Landlord the cost said Roof Repair Agreement and Change Orders
(altogether, the "Repair Costs") in such timely manner as to allow Landlord to
meet the payment schedule established by said Roof Repair Agreement.
Concurrently with payment of the Repair Costs by Tenant to Landlord, Landlord
shall execute a promissory note in favor of Tenant, substantially in the form
attached hereto as Exhibit "C" and made a part hereof, setting forth as the
Principal Sum (as defined therein) the full and complete amount of the Repair
Costs.

        5. Any capitalized terms used herein and not defined herein but defined
in the Lease shall have the same definition as provided for in the Lease.

        6. Except as specifically amended by this Amendment, the terms and
conditions of the Lease shall remain in full force and effect and shall be
binding on the parties hereto and their respective successors and assigns. In
the event of a conflict between the terms of this Amendment and the terms of the
Lease, the terms of this Amendment shall govern.



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        IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered as of the day and year first above written.


ATTEST:                                       REGIONAL INDUSTRIAL DEVELOPMENT
                                              CORPORATION OF SOUTHWESTERN
                                              PENNSYLVANIA


BY:       /s/ Colleen B. Poremski             BY:     /s/ Frank Brooks Robinson
          --------------------------                  --------------------------
(Corporate Seal)                                       President


ATTEST:                                       TOLLGRADE COMMUNICATIONS, INC.


BY:       /s/ Bradley N. Dinger               BY:     /s/ Samuel C. Knoch
          --------------------------                  --------------------------
(Corporate Seal)



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