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                                                                   EXHIBIT 10.41

                           SEVENTH AMENDMENT TO LEASE


        THIS SEVENTH AMENDMENT TO LEASE (this "Amendment") is made and entered
into as of this 9th day of July, 1996, 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"); and

        WHEREAS, the Original Lease was amended by First Amendment of Lease
Agreement dated March 15, 1994 (the "First Amendment"), Second Amendment of
Lease Agreement dated as of July 1, 1994 (the "Second Amendment"), Third
Amendment of Lease Agreement dated as of September 15, 1994 (the "Third
Amendment"), Fourth Amendment of Lease Agreement dated as of September 15, 1994
(the "Fourth Amendment"), Fifth Amendment of Lease Agreement dated March 6, 1995
(the "Fifth Amendment") and Sixth Amendment to Lease dated September 18, 1995
(the "Sixth Amendment"). The Original Lease as amended by the First Amendment,
the Second Amendment, the Third Amendment, the Fourth Amendment, the Fifth
Amendment and the Sixth Amendment is hereinafter called the "Lease"; and

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


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        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 demises unto Tenant 3,600 square
feet of space in the Complex, known as part of the former IDL space and
additionally referred to as "Units B-3 and C-3" (the "Additional Leased
Premises") in as is condition, which space is more particularly shown on Exhibit
"A" which is attached hereto and made a part hereof. Tenant shall pay to
Landlord, as Base Rent for the Additional Leased Premises payable in advance and
without demand on the first business day of each successive calendar month
during the term of the Lease commencing as of March 1, 1996, together with any
escalations provided in the Lease Five and 00/100 Dollars ($5.00) per square
foot of space per year payable in monthly installments of One Thousand Five
Hundred and 00/100 Dollars ($1,500.00). Delivery of the Additional Leased
Premises to Tenant and compliance with all provisions of the Lease occurred on
March 1, 1996. Monthly rental for any partial month shall be prorated. The
Additional Leased Premises shall be deemed to be part of the Premises under the
Lease except that Section 7(B)(b) and Section 33 of the Original Lease shall not
apply to the Additional Leased Premises.

        2. Effective as of the date of termination of Landlord's Lease with IDL
for the Additional IDL Space (as hereinafter defined), which shall in no event
be later than August 31, 1996, the Landlord additionally leases and demises unto
Tenant 13,200 square feet of space in the Complex, known as part of the former
IDL space and additionally referred to as "Units B-4 to B-7" and "Units C-4 to
C-7" in as is condition, which space is



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more particularly shown on Exhibit "A" which is attached hereto and made a part
hereof (the "Additional IDL Space"). Landlord shall deliver possession of the
Additional IDL Space upon vacation of such space by IDL, Inc. The Additional IDL
Space shall be deemed to be part of the Premises under the Lease except that
such Additional IDL Space shall not be subject to Section 7(B)(b) and Section 33
of the Original Lease. Tenant shall pay to Landlord, as Base Rent for the
Additional IDL Space payable in advance and without demand on the first business
day of each successive calendar month during the term of the Lease, the amount
of Three Dollars and Seventy-five Cents ($3.75) per square foot of space,
payable in monthly installments together with any escalations provided for in
the Lease for so long as Tenant uses the Additional IDL Space exclusively for
warehouse purposes. Monthly rental for any partial month shall be prorated. To
the extent that, after the date Tenant begins occupancy of the Additional IDL
Space, there are any improvements to such Additional IDL Space which are made at
Landlord's or Tenant's cost and expense, the rental rate agreed to in this
paragraph shall be renegotiated by Landlord and Tenant but shall be the rate
specified in Section 9 of the Sixth Amendment if the Additional IDL Space is not
used exclusively for warehouse purposes.

        3. Tenant shall provide plans and specifications for any work or
improvements that Tenant plans to undertake in the Additional Leased Premises
and Additional IDL Space to Landlord for Landlord's prior approval which
approval shall not be unreasonably withheld and shall be provided in a timely
manner. All such approved work and improvements shall be done in a good,
workmanlike and lien free manner and in accordance with all requirements in the
Lease.


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        4. 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.

        5. Except as specifically amended hereby, 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 WITNESS WHEREOF, the parties have caused this Amendment to be duly
executed and delivered as of the day and year first above-written.

                                       LANDLORD:

                                       REGIONAL INDUSTRIAL DEVELOPMENT
                                       CORPORATION OF SOUTHWESTERN
                                       PENNSYLVANIA



                                       By: /s/ Frank Brooks Robinson
                                           -------------------------------------
                                       Title: President
                                             -----------------------------------



                                       TENANT:

                                       TOLLGRADE COMMUNICATIONS, INC.



                                       By: /s/ Christian L. Allison
                                           -------------------------------------
                                       Title: CEO
                                              ----------------------------------



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                                    EXHIBIT A



[FLOOR PLAN OF ADDITIONAL LEASED PREMISES]