<PAGE>
                                                                   EXHIBIT 10.34




                                 LEASE AGREEMENT



                                 BY AND BETWEEN



                   REGIONAL INDUSTRIAL DEVELOPMENT CORPORATION
                          OF SOUTHWESTERN PENNSYLVANIA



                                       AND



                         TOLLGRADE COMMUNICATIONS, INC.



                                       FOR



                             HARMAR INDUSTRIAL MANOR
                                 491 NIXON ROAD
                          HARMAR TOWNSHIP, PENNSYLVANIA


                              DATED: AUGUST 5, 1993











<PAGE>




                                 LEASE AGREEMENT

                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
<S>         <C>                                                                                           <C>
SECTION 1.    PREMISES AND TERM.............................................................................1
     A.  Premises...........................................................................................1
     B.  Term...............................................................................................1
     C.  Expansion..........................................................................................1
SECTION 2.    EXTENSION BY MUTUAL CONSENT...................................................................2
SECTION 3.    RENT AND ADDITIONAL RENT......................................................................2
     A.  Rent...............................................................................................2
     B.  Additional Rent - Real Estate Taxes................................................................3
     C.  Additional Rent - Maintenance and Operations.......................................................4
     D.  Payment Provisions.................................................................................6
SECTION 4.    UTILITIES.....................................................................................6
SECTION 5.    USE...........................................................................................6
SECTION 6.    ALTERATIONS...................................................................................7
SECTION 7.    MAINTENANCE...................................................................................9
SECTION 8.    ASSIGNMENT AND SUBLETTING....................................................................12
SECTION 9.    RIGHT OF ENTRY...............................................................................13
SECTION 10.   SURRENDER....................................................................................13
SECTION 11.   INDEMNIFICATION..............................................................................14
SECTION 12.   LIABILITY INSURANCE..........................................................................14
SECTION 13.   FIRE AND CASUALTY INSURANCE..................................................................15
SECTION 14.   WAIVER OF SUBROGATION........................................................................15
SECTION 15.   DAMAGE OR DESTRUCTION OF LEASED PREMISES.....................................................15
SECTION 16.   DEFAULT; REMEDIES OF LESSOR..................................................................16
SECTION 17.   EMINENT DOMAIN...............................................................................17
SECTION 18.   SUBORDINATION OF LEASE.......................................................................18
SECTION 19.   ESTOPPEL CERTIFICATE.........................................................................19
SECTION 20.   FORCE MAJEURE................................................................................19
SECTION 21.   QUIET ENJOYMENT..............................................................................20
SECTION 22.   ABANDONMENT OF PREMISES......................................................................20
SECTION 23.   NON-WAIVER...................................................................................20
SECTION 24.   NOTICES......................................................................................21
SECTION 25.   SUCCESSORS AND ASSIGNS.......................................................................21
SECTION 26.   ENVIRONMENTAL MATTERS........................................................................21
SECTION 27.   GOVERNING LAW................................................................................25
</TABLE>


<PAGE>


<TABLE>
<CAPTION>
<S>         <C>                                                                                           <C>
SECTION 28.   SEVERABILITY.................................................................................25
SECTION 29.   GENDER.......................................................................................25
SECTION 30.   OPTION TO RENEW..............................................................................25
SECTION 31.   ENTIRE AGREEMENT.............................................................................26
SECTION 32.   LESSOR IMPROVEMENT ADVANCE...................................................................26
SECTION 33.   HVAC SYSTEM..................................................................................26
</TABLE>


EXHIBIT A FLOOR PLAN
EXHIBIT B LESSOR'S IMPROVEMENTS



<PAGE>


                                 LEASE AGREEMENT

                             HARMAR INDUSTRIAL MANOR

                  THIS LEASE, made as of this 5th day of August, 1993, between
REGIONAL INDUSTRIAL DEVELOPMENT CORPORATION OF SOUTHWESTERN PENNSYLVANIA,
hereinafter called "Lessor," and TOLLGRADE COMMUNICATIONS, INC., a Pennsylvania
corporation, hereinafter called the "Lessee."

SECTION 1.        PREMISES AND TERM.

        A. PREMISES. The Lessor does hereby lease and demise unto the Lessee (i)
Suite 101 containing twenty three hundred square feet (2300 sq. ft.) of rental
area of finished office space, (ii) Suite 102 containing approximately two
thousand square feet (2000 sq. ft.) of rentable area of unfinished office space,
(iii) Unit A-1 containing a total of approximately seven thousand seven hundred
eighty five square feet (7785 sq. ft.), (iv) Unit A-5 containing two thousand
square feet (2000 sq. ft.) of rentable area and (v) Unit A-6 containing twenty
five hundred square feet (2500 sq. ft.) of rentable area (the "Premises") in the
HARMAR INDUSTRIAL MANOR, (the "Complex"), located in Harmar Township, Allegheny
County, Pennsylvania, as identified in EXHIBIT "A." Lessee and its employees and
business invitees shall also be entitled to use, in common with others, the
sidewalks and parking areas (hereinafter called the "Common Areas"), which areas
constitute a part of the Complex. Lessor guarantees that Lessee shall be
entitled to seven (7) executive parking spaces in the front parking area,
sixty-one (61) parking spaces in the side parking area, plus an additional five
(5) parking spaces per 1000 square feet of Premises taken under Lessee's
expansion option pursuant to SECTION 1(c) hereof.

        B. TERM. Subject to the provisions of Section 6 hereof, the term of this
Lease shall commence, (the "Commencement Date") and possession shall be given as
of 12:01 AM on or about September 1, 1993. The term of this Lease shall expire
(the "Expiration Date") at 11:59 PM on December 31, 1998 unless the term is
extended hereinafter provided in this Lease. Any other Commencement Date
agreeable to the parties hereto shall be evidenced by an amendment to this
Lease.

        C. EXPANSION. Lessee shall have the option to lease certain additional
space adjacent to the Premises currently leased to IDC, Inc. (the "IDC Space")
and additional areas in the building in which the Premises are located as
existing leases in such building expire. With respect to the IDC Space, Lessee
shall be entitled to lease such space at any time, upon one hundred twenty (120)
days prior notice to Lessor, so



<PAGE>


long as IDC, Inc. is still the tenant of such space under a lease under a lease
under which Lessor has a lease termination right. With respect to other
additional areas in the building in which the Premises are located (except for
the IDC Space) Lessor shall provide Lessee with notice of the pending expiration
of the existing leases. Lessee shall have sixty (60) days from the receipt of
Lessor's notice to exercise its option for such space. Expansion into the
adjacent warehouse area will be at $4.75 per square foot if such expansion
occurs before December 31, 1993 and any other such areas and any space in the
adjacent warehouse area after December 31, 1993 shall be at the prevailing
market rate. In the event Lessee needs to expand the Premises and Lessor cannot
accommodate Lessee's expansion needs, or if Lessee needs additional parking
spaces to accommodate its expansion and Lessor cannot accommodate such parking
needs as required in SECTION 1(A), Lessee shall have the right to terminate this
Lease provided Lessee pays the unamortized portion of Lessor's Improvement
Advance plus the portion of the real estate commission referenced in SECTION 31
equal to the balance of the term remaining; PROVIDED, HOWEVER, that if Lessee
has, within the prior ninety (90) day period, received notice from Lessor of the
availability of additional space, and Lessee did not exercise its option to
lease such space, it must give Lessor three (3) months prior notice of its
intent to terminate this Lease.

SECTION 2.        EXTENSION BY MUTUAL CONSENT.

        If Lessee occupies the Premises after the end of the term, this Lease
and all of its terms, provisions, conditions, covenants, waivers, remedies and
any and all of Lessor's rights herein specifically given and agreed to, shall be
in force for one month thereafter and thereafter from month to month as long as
the relationship of Lessor and Lessee continues.

SECTION 3.        RENT AND ADDITIONAL RENT.

        A. RENT.

           As rental ("Base Rent") for the Premises, Lessee shall pay to the
Lessor at its office in Pittsburgh beginning on or about September 1, 1993 and
on the first business day of each successive calendar month, in advance and
without demand, the following sums:

           If the date on which Base Rent commences is on a day other than the
first business day of a calendar month, Lessee shall pay to Lessor with the
first complete monthly rental payment due, a pro rata portion to be based on the
number of days the Premises are occupied in such partial month after the
commencement of rental payments.




                                      -2-
<PAGE>


             Months

               1-8         $    3,175.39
              9-12         $    6,350.77
             13-64         $    7,340.35
                           -------------
             TOTAL           $432,504.40

    B.  ADDITIONAL RENT - REAL ESTATE TAXES.

        In the event the real estate taxes payable by Lessor on the Complex for
the period 1995 or any subsequent year of the term hereof, shall exceed the
amount payable by Lessor for such taxes for the period of 1994, then Lessee
shall pay, in four (4) equal payments payable monthly on the first day of each
month following Lessee's receipt of notice of such increase ("Lessee's Tax
Responsibility"), an amount equal to that portion of such excess determined
annually that the area of the Premises (as shown in EXHIBIT "A"), as may be
expanded by time to time, bears to the total rentable area of the Complex
(111,600 sq. ft.); provided that, in the event a sale of the Complex or the
building in which the Premises are located causes an unusual increase in the tax
assessment for the building or the Complex, Lessee shall not be required to pay
such unusual increase in taxes. In such event, Lessee's Tax Responsibility for
such taxes shall be equal to the amount payable for the prior year's taxes,
before the sale resulting in an unusual increase.

        In the event that Lessee's Tax Responsibility is payable due to an
increase in real estate taxes, then on or before February 15, 1994 and on or
before February 15 of each year thereafter, Lessor shall furnish Lessee a
written statement, with copies of bills from the respective taxing authorities,
which statement shall show the computation of such excess for the preceding
calendar year. Any special assessment, apart from Lessee's Tax Responsibility,
shall be amortized over such reasonable period as is determined by Lessor based
upon the nature and extent of the improvement or betterment for which such
special assessment is levied.

        For the purpose of determining the applicability of real estate taxes
for each calendar year, in the event that real estate taxes are levied on the
basis of a tax year, which does not coincide with a calendar year, then such
taxes shall be deemed to apply to each tax year.

        If at any time during the term hereof the methods of taxation prevailing
at the commencement of the term hereof shall be altered so that in lieu of, or
as a supplement to, or a substitute for the whole or any part of the real estate
taxes or assessments now levied, assessed, or imposed upon the Complex, there
shall



                                      -3-
<PAGE>


be levied, assessed, or imposed any form of assessment, tax, license fee,
license tax, business license fee, business license tax, excise tax, commercial
rental tax, levy, charge, penalty, or other imposition by the federal or state
government, any political subdivision, municipality, school district, or other
taxing body, which constitutes (1) a tax, levy, assessment, fee, imposition or
other charge upon the rent payable hereunder, the Lessor's right to rent or
other income from the Complex or upon the Lessor's right to rent or other income
from the Complex or upon the Lessor's business of leasing the Complex; or (2) a
tax, levy, assessment, fee, imposition or other charge allocable to or measured,
in whole or in part, by the area of the Complex or rent payable hereunder; or
(3) a tax, levy, assessment, fee, imposition or other charge upon this
transaction or any document related thereto, or upon the status of Lessor or
Lessee as such; or (4) any tax, levy, assessment, fee, impositions or other
charge upon or with respect to the possession, leasing, operating, management,
maintenance, alteration, repair, use or occupancy of the Complex; then Lessee's
pro rata share of all such taxes, assessments, fees, levies, impositions,
charges, or the part thereof so measured or based, which constitute a supplement
to the real estate taxes or assessments now levied, assessed or imposed upon the
Premises, shall be payable by Lessee as Additional Rent in equal, monthly
installments or, in the alternative, as the case maybe, all such taxes,
assessments, levies, impositions and charges or the part thereof so measured or
based, which are in lieu of or a substitute for the whole or any part of the
real estate taxes or assessments now levied, assessed or imposed on the
Premises, shall be payable by Lessee as annual rent in equal monthly
installments in lieu of that portion part of the annual rent now attributable to
the affected portion of the real estate taxes now levied, assessed or imposed on
the Premises.

        Real estate taxes in any such year shall be reduced by the net amount of
any tax refund received by Lessor during such year and all payments in such year
shall be paid so as to take advantage of any discount. Real estate taxes shall
not include any federal, state or local sales, use, franchise, capital stock,
inheritance, general income, gift or estate taxes.

    C.  ADDITIONAL RENT - MAINTENANCE AND OPERATIONS.

        If the expenses for maintaining and operating the Complex during the
period beginning September 1, 1994 and ending August 31, 1995, or during each
subsequent time period thereafter exceed the expenses for maintaining and
operating the Complex during the period beginning September 1, 1993 and ending
August 31, 1994, then the Lessee shall pay to the Lessor as Additional Rent the
portion of such excess attributable to the Premises, such Additional Rent to be
paid in twelve equal monthly installments commencing January 1 of the calendar
year



                                      -4-
<PAGE>


immediately succeeding the time period in which such excess occurs; PROVIDED,
however, that any such Additional Rent shall not be due and payable beyond the
term of this lease. On or before December 15, 1994, and on or before December 15
of each calendar year thereafter, the Lessor shall furnish to the Lessee a
written statement showing the computation of such excess, if any, for the
preceding applicable time period and showing the amount of Additional Rent for
which the Lessee shall be obligated under this paragraph.

        The portion of any such excess expenses for maintaining and operating
the Complex attributable to the Premises shall be prorated based upon the
proportion that the area of the Premises (as shown in EXHIBIT "A"), as may be
expanded from time to time, bears to the total rentable area of the Complex
(111,600 sq. ft.). The term "expenses" for maintaining and operating the Complex
shall be deemed to mean those out-of-pocket expenses incurred during such
operating year in respect of the operation and maintenance of the Complex in
accordance with accepted principles of sound management and generally accepted
accounting practices ("GAAP") as applied to the operation and maintenance of
first class office/industrial buildings in the metropolitan Pittsburgh area.
Such expenses shall include, but not be limited to, premiums for insurance
carried by the Lessor. The term "insurance" shall include: fire and extended
coverage insurance; vandalism and malicious mischief insurance, boiler
insurance; rent insurance; elevator insurance; public liability insurance; and
such other insurance policies as may hereafter be deemed appropriate for
multiple-tenancy office/industrial buildings.

        Such expenses shall not include (i) expenses for any capital improvement
made to the land or building; (ii) expenses for painting, redecorating or other
work which the Lessor performs as a special service for another lessee in the
Complex (that is, other than painting, redecorating or other work which is a
standard service for the Lessees of the Complex); (iii) expenses for repairs or
other work occasioned by fire, windstorm or other insurable casualty; (iv)
expenses incurred in leasing or procuring new lessees including lease
commissions, advertising expenses and expenses of renovating space for new
lessees; (v) legal expenses in enforcing the terms of any lease; (vi) interest
or amortization payments on any mortgage; (vii) wages, salaries or other
compensation paid to any employees above the grade of building superintendent;
(viii) wages, salaries or other compensation paid for clerks or attendants in
concessions operated by the Lessor; (ix) fines or penalties resulting from
Lessor's violations of law; (x) costs incurred due to the breach by Lessee or
any other tenant of the terms of any lease or other agreement; or (xi) any costs
involved in the commercial concessions operated by Lessor.



                                      -5-
<PAGE>


        Lessor shall maintain books and records of expenses and real estate
taxes in accordance with GAAP and sound management practices. Lessor shall
provide Lessee with any and all relevant information evidencing any expenses or
real estate taxes paid by Lessor which are charged to Lessee as Additional Rent
or Lessee's Tax Responsibility. In the event that a review of such information
by Lessee discloses that expenses or real estate taxes have been overstated by
Lessor for the period reviewed by Lessee, Lessor shall make an adjustment of
Additional Rent and/or Lessee's Tax Responsibility to reflect such
overstatement.

    D.  PAYMENT PROVISIONS.

        Lessee hereby covenants and agrees to pay the rent hereby reserved as
and when due, and also all sums of money, charges or other amounts required to
be paid by the Lessee to the Lessor which shall be "rent" in addition to the
rent provided for herein. Nonpayment of additional rent when due shall
constitute a default under this Lease, unless being disputed in good faith, to
the same extent, and shall entitle the Lessor to the same remedies, as
nonpayment of rent.

        Rent payments shall be made by check payable to the RIDC shall be
delivered or mailed, postage prepaid, to:

                  Regional Industrial Development Corporation
                  Post Office Box 360146M
                  Pittsburgh, Pennsylvania 15251-6146

SECTION 4.        UTILITIES.

        Lessee agrees to pay to respective utility companies utility charges for
water, electricity, gas and sewage, separately metered to Lessee. In the event
Lessee fails to pay the same when due, Lessor shall have the right to pay the
same and collect the amount thereof from Lessee in the same manner as Additional
Rent.

SECTION 5.        USE.

        Lessee will not engage upon the Premises in any trade or occupation
which is in violation of law. Lessee shall use the Premises as
office/warehouse/light manufacturing space related to its corporate purpose. The
Premises are not to be used for rental sales or displays for such purposes.
Product displays will be permitted provided the same cannot be seen outside the
Premises.



                                      -6-
<PAGE>


        Lessee shall not use or occupy the Premises for any other purpose or
business without the prior written consent of Lessor, which consent shall not be
unreasonably withheld or delayed.

        Lessee shall comply with the following rules and regulations covering
the use of the Premises and will at all times observe, perform and abide by all
rules and regulations from time to time promulgated by Lessor for the common use
of the Harmar Industrial Manor the safety, care and cleanliness of the Premises:

        (i) That it will not obstruct for use of the common areas including the
sidewalks and parking lot and that it will keep clean the said common areas.

        (ii) That it will use the parking area to be provided in the front of
the Premises only for visitor parking and executive parking; that the parking
area to the side of the Premises shall be used for employee and other parking.

        (iii) That it will not install or post any exterior signs on or over the
Premises except those approved in writing in advance by Lessor.

        (iv) Nothing shall be placed by the Lessee or its employees on the
outside of the Premises or on the windows, window sills or projections.

        All such rules and regulations shall apply to Lessee and its employees,
agents, licensees, invitees, subtenants and contractors. Lessor represents and
warrants that such rules and regulations shall also apply to the other tenants
in the Complex and that Lessor shall enforce such rules and regulations against
such other tenants.

        Anything in this Lease contained to the contrary notwithstanding, Lessor
covenants and represents that the Premises conform to the requirements, laws,
rules and regulations imposed, enacted or promulgated by all governments and
governmental bodies having jurisdiction over the Complex and the Premises; and
that the Premises may lawfully be used for the purposes herein permitted.

SECTION 6.        ALTERATIONS.

        Lessee acknowledges and agrees that certain improvements to the Premises
are to be completed by Lessor, in compliance with the specifications set forth
in Exhibit "B" attached hereto ("Lessor's Improvements"). Lessor represents that
to the best of its knowledge and belief after completion of Lessor's
Improvements the Complex and the Premises will be suitable for the purposes



                                      -7-
<PAGE>


contemplated by Lessee, as such contemplated purposes have been communicated by
Lessee to Lessor. EXHIBIT "A" which is attached hereto and made a part hereof is
a "Floor Plan" of the Premises.

        Lessor shall use its best efforts to complete Lessor's Improvements by
September 1, 1993. In the event that Lessor's Improvements are not substantially
completed by September 1, 1993, Lessee shall have the option, in its sole
discretion, of either: (1) occupying the Premises, allowing the Lease to
commence, and having payments of Rent and Additional Rent abated until such time
as Lessor's Improvements are substantially complete; or (2) not occupying the
Premises, and having the term of the Lease not commence until Lessor's
Improvements are substantially complete.

        Lessor's Improvements and any and all additions, alterations and
improvements made by the Lessee ("Lessee's Improvements"), shall be done in a
good and workmanlike manner.

        Prior to the commencement of construction of Lessee's Improvements,
Lessee shall furnish to Lessor the plans and specifications of the construction
work to be undertaken, shall furnish information as to the equipment to be
installed, and shall obtain Lessor's written approval of said plans and
specifications, which approval shall not be unreasonably withheld. Lessor shall
obtain all necessary permits required by governmental authorities having
jurisdiction prior to the commencement of construction of Lessee's Improvements.

        Lessee's Improvements shall become the property of the Lessor and shall
remain upon and be surrendered with the Premises at the expiration or earlier
termination of this Lease.

        It is not intended to include in the expression "additions, alterations
and improvements," any mechanical equipment and trade fixtures installed by the
Lessee, all of which shall may be removed by Lessee on the termination of this
Lease if (i) Lessee is not in default hereunder, (ii) such removal does not
damage the Premises, and (iii) any damage that may be occasioned by any such
removal shall be repaired by Lessee in a good and workmanlike manner.

        If Lessor so directs by written notice to Lessee, prior to the
expiration of this Lease, or within fifteen (15) days thereafter, the Lessee
shall promptly remove all fixtures or mechanical equipment which were placed in
the Premises by Lessee and which are designated in said notice. Lessee shall
repair any physical damage occasioned by such removal, and in default, thereof,
Lessor may effect said removals and repairs at Lessee's expense.



                                      -8-
<PAGE>


        Lessee may bring such equipment, furniture, trade fixtures or other
personal property into the Premises as may be necessary for its business;
PROVIDED, HOWEVER, that Lessee shall first notify Lessor of the type and nature
of such personal property to be brought onto the Premises. Should such personal
property be of an unusual size, type, or weight, so as to adversely affect the
Complex, then Lessor reserves the right to restrict the use of same in the
Premises.

        Lessee will not file, nor will it permit or suffer any contractor or
subcontractor, materialman or mechanic or other person under it to file, nor
shall any contractor, subcontractor, materialman or mechanic file any mechanics'
lien or other liens or claims for work done or materials furnished in or about
the Premises against the Premises or the structure of which it is a part. Unless
Lessor otherwise agrees, in writing, prior to the commencement of any work on
the Premises, Lessee shall file in the office of the Prothonotary of Allegheny
County a waiver of the right to file liens which shall be in usual form for such
waivers, such form to be approved by the Lessor.

        Notwithstanding the foregoing, if any mechanics' or other lien shall be
filed against the Premises or the Complex purporting to be for labor or material
furnished or to be furnished at the request of Lessee, then Lessee shall, at its
expense, cause such lien to be discharged of record by payment, bond or
otherwise, within thirty (30) days after the filing thereof. If Lessee shall
fail to cause such lien to be discharged of record within such ten-day period,
or, if such lien is contested by Lessee and Lessee fails to provide adequate
security for Lessor's protection; then Lessor may cause such lien to be
discharged by payment, bond or otherwise, and Lessee shall, upon demand,
reimburse Lessor for all reasonable amounts paid and costs incurred including
attorneys' fees, in having such lien discharged of record.

        The taking of possession of the Premises by Lessee shall establish that
the Premises and the Complex were at such time in satisfactory condition, except
for Lessor's Improvements, latent defects, order and repair.

SECTION 7.        MAINTENANCE.

        A. LESSEE COVENANTS AS FOLLOWS:

                a. That Lessee will, at its own expense, replace any glass
broken on the Premises and repair, restore, or replace all partitions and
fixtures that may be installed by it which are damaged or destroyed by any
cause.



                                      -9-
<PAGE>

                b. That Lessee shall make all nonstructural repairs to the
interior of the Premises, including, but not limited to, repairs and replacement
of, if necessary, the plumbing and electrical fixtures, the doors and locks, and
all maintenance and nominal repairs to the air conditioning and heating
equipment.

                c. That Lessee shall make all repairs and, if necessary the
replacement, of any nature to any part of the Premises necessitated by the act
or neglect of Lessee.

                d. That Lessee shall make no modifications to any parts of the
structure of the Premises without written approval of Lessor, which approval
shall not be unreasonably withheld. This shall be deemed to include the floor
slabs, perimeter walls and the roof of the Premises as well as any suspensions
from the roof structure.

                e. That Lessor will keep the exterior of the entire Premises,
including adjoining sidewalks free of rubbish, debris, snow or ice, and also in
such condition as the Board of Health and Board of Fire Underwriters having
authority in such matters may lawfully require. Lessor will ensure that snow and
ice removal is done in a timely manner. Lessee further agrees at its sole cost
and expense, to perform, fully obey and comply with all ordinances, rules
regulations and laws of all public authorities, boards and officers, relating to
the maintenance of and occupancy of said Premises.

                f. That Lessee shall remove no additional, improvements and
alterations made by Lessor or by Lessee except as herein provided, and shall not
alter the Premises or any part thereof, without in each case the consent of
Lessor in writing. Lessee shall, however, have the right, during the term of
this Lease, to remove its trade fixtures and mechanical equipment however
affixed to the realty, and Lessee covenants promptly to repair any damage caused
by any such removal; PROVIDED, HOWEVER, that any such trade fixtures and
mechanical equipment, not required to be removed by Lessor pursuant to this
Lease, which shall not have been removed by Lessee on the expiration or sooner
termination of their term of this Lease or any extended term hereof, shall
deemed abandoned by Lessee and shall thereupon become the absolute property of
Lessor without compensation to Lessee.

                Anything herein contained to the contrary notwithstanding,
however, it is agreed that the Lessor's consent shall be required for
installation of improvements, alterations, or repairs, whether or not such
involve alteration to the building structure, and that Lessor will not
unreasonably withhold its consent as to the making of other installations,
alterations, additions or improvements which are



                                      -10-
<PAGE>


reasonably required for the conduct of Lessee's business on the Premises,
provided that such installations, alterations, additions or improvements do not
adversely affect the structures upon, or the overall visual environment of the
Complex.

                g. That Lessee shall make, at its sole cost and expense, all
repairs necessary to maintain the Premises, pursuant to subparagraphs "a"
through "f" hereinabove written, and shall keep the Premises and the fixtures
therein in neat and orderly condition. If Lessee refuses or neglects to make
such repairs, or fails to diligently prosecute the same to completion, after
written notice from Lessor of the need therefore, and after a reasonable time
thereafter in which to make the same, Lessor may make such repairs at the
expense of Lessee and such expense shall be collectible as Additional Rent.

                h. That a violation by Lessee, its employees or its agents of
any of the covenants above written in subparagraphs "a" through "g" shall be
deemed a default under this Lease entitling Lessor to exercise any of the
remedies provided for herein.

                i. That Lessor shall not be liable by reason of any injury to or
interference with Lessee's business arising from the making of any repairs,
alterations, additions or improvements in or to the Premises or the Complex or
to any appurtenances or equipment therein unless such inconvenience, injury, or
interference shall be occasioned by the negligence of Lessor, its agents,
servants, and/or employees. There shall be no abatement of rent because of such
repairs, alterations, additions or improvements, except as provided in SECTION
15 hereof. Lessor shall use its best efforts with respect to repairs,
alterations, additions and improvements to avoid depriving Lessee of the use of
the Premises and to minimize or eliminate any interference with Lessee's use of
the Premises except in cause of damage by fire or other casualty covered by
SECTION 15.

        B.       LESSOR COVENANTS AS FOLLOWS:

                a. That Lessor shall make all structural repairs in, to and
about the Premises and all repairs and maintenance of the Complex of which they
are a part, which repairs and maintenance are Lessor's responsibility as set
forth in this Lease, needed to keep the Premises and the Complex in good and
tenantable condition.

                b. That Lessor shall be responsible for repair and replacement
of certain components within those air conditioners and heating units, which
were installed by Lessor. Lessor's responsibility for said repairs and
replacements shall be contingent upon Lessee obtaining, at Lessee's expense,
annual maintenance



                                      -11-
<PAGE>


contracts, which contracts shall require a minimum of semi-annual service calls.
Such contracts must be with a reputable heating, ventilating, and air
conditioning service company, which company is subject to the reasonable
approval of Lessor. Lessor shall not be responsible for any repairs or
replacement of any unit without Lessee providing a documented history to Lessor
of every service call made during Lessee's occupancy for the unit in question.
Lessee shall, upon taking occupancy of the Premises and upon each renewal of
said maintenance contract, supply Lessor with a copy of said contract.

                Lessor's responsibility for maintenance of certain components
within those air conditioning and heating units previously installed by Lessor
shall be further limited to the repair and replacement of certain components of
air conditioners and heating units consisting exclusively of compressor(s),
condenser(s), evaporator coil(s), fan housing(s), heat exchanger(s), and
motor(s).

                Except as provided in the preceding paragraph, Lessee shall be
responsible for on-going maintenance, repairs, and replacements of components
within the air conditioning and heating units serving the Premises.

                c. That Lessor shall be responsible for the removal of snow from
the driveways and parking areas of the Complex.

                d. That Lessor shall be responsible for the management of all
landscaped areas comprising a part of the Complex.

        If Lessor refuses or neglects to make such repairs for which it has
responsibility under this Lease, or fails to diligently prosecute the same to
completion, after written notice from Lessee of the need therefore, and after a
reasonable time thereafter in which to make the same, Lessee may make such
repairs at the expense of Lessor and such expense shall be credited against the
rent. In no event shall Lessor be obligated under this SECTION 7 to repair any
damage caused by any act, omission or negligence of Lessee or its employees,
agents, invitees, licensees, subtenants or contractors.

SECTION 8.        ASSIGNMENT AND SUBLETTING.

        Lessee may assign this Lease or sublet all or any part of the Premises
with the prior written consent of Lessor, which consent shall not be withheld
unreasonably; PROVIDED, HOWEVER, that Lessee shall remain liable for the payment
of rent hereunder and the performance of the covenants and conditions contained
herein. No consent will be required for any assignment: (1) to any present or
future



                                      -12-
<PAGE>


wholly-owned subsidiary or parent of Lessee or (2) to any successor in interest
of the entire business of Lessee as a result of merger, consolidation, purchase,
assignment, or operation of law.

SECTION 9.        RIGHT OF ENTRY.

                  Lessor, its employees and agents, shall have the right to
enter the Premises with twenty-four (24) hours prior notice to Lessee at all
reasonable business hours for the purposes of examining, inspecting or showing
the same to prospective purchasers, mortgagees, or during the last six (6)
months of the term to prospective tenants, and making such alterations, repairs,
improvements or additions to the Premises or to the Complex as are necessary to
ensure compliance with the Lease. Prior to Lessor or its employees and agents
entering the Premises, Lessor shall provide reasonable notice to Lessee except
in the event for an emergency. Nevertheless, if representatives of Lessee shall
not be present to open and permit entry into the Premises at any time when such
entry by Lessor is necessitated by emergency, then Lessor may enter by means of
a master key (or forcibly in the event of an emergency) without such entry
constituting an eviction of Lessee or termination of this Lease.

SECTION 10.       SURRENDER.

                  At the expiration of this Lease or sooner termination of the
term of this Lease or any extended term hereof, Lessee shall surrender the
Premises to Lessor, together with all additions, alterations and improvements
thereto, in broom clean condition and in good order and repair except for
ordinary wear and tear for which Lessee is not obligated to make repairs under
this Lease. Lessee, however, shall remove all additions, alterations,
improvements, installations, trade fixtures or mechanical equipment which Lessor
shall have made the election to have removed as provided for in the Lease.

                  Lessee expressly waives to Lessor the benefit of Act No. 20,
approved April 6, 1951, entitled "The Lessor and Lessee Act of 1951" requiring
three months' notice to vacate the Premises at the end of the term or upon
forfeiture of this Lease for breach of its conditions, and covenants and agrees
to give up quiet and peaceable possession without further notice form the Lessor
or its agent.



                                      -13-
<PAGE>

SECTION 11.       INDEMNIFICATION.

        A. LESSEE. Lessee shall indemnify, hold harmless and defend Lessor from
and against any and all costs, expenses (including reasonable counsel fees),
liabilities, losses, damages, suits, actions, fines, penalties, claims or
demands of any kind and asserted by or on behalf of any person or governmental
authority, arising out of or in any way connected with, and Lessor shall not be
liable to Lessee on account of, (i) any failure by Lessee to perform any of the
agreements, terms, covenants or conditions of this Lease required to be
performed by Lessee, (ii) any failure by Lessee to comply with any statutes,
ordinances, regulations or orders of any governmental authority relating to the
use and occupancy of the Premises and improvements, (iii) any accident, death or
personal injury, or damage to or loss or theft of property, which shall occur in
or about the Premises except as the same may be caused solely by the negligence
or intentional wrongdoing of Lessor, its employees or agents or failure of
Lessor to observe its covenants hereunder, or (iv) any loss or damage which
Lessee, its agents, or employees, may sustain by reason of any strike, lockout
or other labor disturbance, or civil commotion affecting the Lessor or the
Complex or any other tenant of the Lessor.

        B. LESSOR. Lessor shall indemnify, hold harmless and defend Lessee from
and against any and all costs, expense (including reasonable counsel fees),
liabilities, losses, damages, suits, actions, fines, penalties, claims or
demands of any kind and asserted by or on behalf of any person or governmental
authority, arising out of or in any way connected with, and Lessee shall not be
liable to Lessor on account of, (i) any failure by Lessor to perform any of the
agreements, terms, covenants or conditions of this Lease required to be
performed by Lessor, (ii) any failure by Lessor to comply with any statutes,
ordinances, regulations or orders of any governmental authority relating to the
use and occupancy of the Premises and improvements except where Lessee is
responsible for compliance therewith, (iii) any accident, death or personal
injury, or damage to or loss or theft of property, which shall occur in or about
the Premises except as the same may be caused solely by the negligence or
intentional wrongdoing of Lessee, its employees or agents or failure of Lessee
to observe its covenants hereunder.

SECTION 12.       LIABILITY INSURANCE.

        A. LESSEE. Lessee will at Lessee's cost and expense maintain with
insurance companies satisfactory to Lessor during the term of this Lease,
comprehensive public liability insurance with minimum combined single limits of



                                      -14-
<PAGE>


$1,000,000 for bodily injury liability and property damage liability. Such
insurance coverage shall name Lessor as an additional insured, as its interest
may appear. Lessee shall deposit with Lessor certificates of such insurance at
or prior to the commencement of this Lease and thereafter within ten (10) days
prior to the expiration of such policy or policies.

        B. LESSOR. Lessor will at Lessor's cost and expense maintain with
insurance companies satisfactory to Lessor during the term of this Lease,
comprehensive public liability insurance with minimum combined single limits of
$1,000,000 for bodily injury liability and property damage liability. Lessor
will procure and maintain during the term hereof, at its sole cost and expense,
insurance against all risks of direct physical loss, including loss by fire,
lightning and other risks which at the time are included under "extended
coverage" endorsements, in amounts not less than one hundred percent (100%) of
the actual replacement value of the Complex exclusive of foundations and
excavations. Lessor shall deposit with Lessee certificates of such insurance at
or prior to the commencement of this Lease and thereafter within ten (10) days
prior to the expiration of such policy or policies.

SECTION 13.       FIRE AND CASUALTY INSURANCE.

        Lessee shall not do or suffer to be done any act, matter or thing
whereby the fire and casualty insurance carried by Lessor on the Complex of
which the Premises are a part shall be suspended or rated as more hazardous than
at the commencement of this Lease. In case of breach of this covenant (in
addition to all other remedies given to Lessor for breach of any covenants or
conditions of this Lease), Lessee agrees to pay as Additional Rent any and all
increase of premium for insurance carried by Lessor caused in any way by the
actions or occupancy of Lessee.

SECTION 14.       WAIVER OF SUBROGATION.

        The parties hereto for themselves and their insurers hereby waive any
right of subrogation against the other party.

SECTION 15.       DAMAGE OR DESTRUCTION OF LEASED PREMISES.

        In case the structure of which the Premises form a part shall be
structurally damaged, to the extent of 50% or more of its value, by fire or
other cause then, at the option of the Lessor, to be exercised by a notice in
writing sent no later than thirty (30) days after such damage, this Lease shall
cease and come to an



                                      -15-
<PAGE>


end as of the date of such damage, and any fixed rent for the unexpired period
paid in advance beyond the date of such damage, shall be refunded by Lessor to
Lessee.

                If the said structure shall be damaged to an extent less than
50% of its value, or if the Lessor shall not exercise its aforesaid option, the
Lessor, with due diligence, shall restore the structure to a condition equal to
its condition before the damage, which will permit the full enjoyment and use of
the Premises. A proportion of the fixed rent herein reserved, according to the
extent that such damage and its repair shall interfere with the full enjoyment
and use of the Premises, shall be suspended and abated from the date of such
damage until said structure shall have been so restored.

        The Lessee shall be obligated to repair, restore or replace trade
fixtures and equipment installed by Lessee which may be damaged or destroyed by
any cause.

SECTION 16.       DEFAULT; REMEDIES OF LESSOR.

        The occurrence of any of the following shall constitute an Event of
Default under this Lease:

        (a) If Lessee shall fail to pay rent or any other sum due hereunder to
Lessor when the same is due and payable under the terms of this Lease and such
failure shall continue for a period of ten (10) days after written notice
thereof has been given to Lessee by Lessor, or (b) the Lessee shall fail to
perform any other duty or obligation imposed upon it by this Lease and such
failure shall continue for a period of thirty (30) days after written notice
thereof has been given to Lessee by Lessor, unless such default cannot be
reasonably remedied within thirty (30) days after receipt of Lessor's notice, in
which event Lessee shall have such additional time as may be reasonably
necessary to remedy such default, or (c) the Lessee shall be adjudged bankrupt,
or shall make a general assignment for the benefit of its creditors, or (d) a
receiver for any property of Lessee in or upon the Premises is appointed in any
action, suit or proceeding by or against Lessee and such appointment shall not
be vacated or annulled within sixty (60) days, or (e) the interest of Lessee in
the Premises shall be sold under execution or other legal process.

        Upon the occurrence of an Event of Default, Lessor shall have the right
to enter upon the Premises and again have, repossess, and enjoy the same as if
this Lease had not been made, and thereupon, at Lessor's option, this Lease
shall terminate without prejudice, however, to the right of Lessor to recover
from Lessee



                                      -16-
<PAGE>


all rent due and unpaid up to the time of such re-entry. In the event of any
such Event of Default and re-entry, if Lessor does not elect to terminate this
Lease, Lessor shall make its best effort to relet the Premises for the remainder
of the term, for the highest rent then reasonably obtainable, and Lessee shall
be liable to Lessor and Lessor shall have the right to recover from Lessee the
difference between the rent reserved under this Lease for the remainder of the
term and the amount obtained through such reletting plus the costs and expenses
reasonably incurred by Lessor in such reletting including, without limitation,
the reasonable cost of obtaining possession of the Premises and of any repairs
or alterations necessary to repair the same. In the event that the amount
obtained through such reletting, plus the reasonable costs and expenses thereof,
shall exceed the rent herein reserved, Lessor shall retain such excess and use
such excess for its sole purpose.

        Notwithstanding anything to the contrary contained herein, Lessor
expressly waives the benefit to Lessor of any rights it may have under law to
distraint of any of Lessee's personal property.

        Lessee agrees that Lessor's remedies under this Lease are cumulative and
the exercise of one remedy does not preclude the exercise of the other remedies.

        Lessor shall not be deemed to be in default in the performance of any
obligation required to be performed by Lessor hereunder unless and until it has
failed to perform such obligation within thirty (30) days after written notice
thereof from Lessee to Lessor; PROVIDED, HOWEVER, that if the nature of the
Lessor's obligation is such that more than thirty (30) days are required for its
performance, then Lessor shall not be deemed to be in default if it shall
commence such performance within such thirty-day period and thereafter
diligently prosecutes the same to completion.

SECTION 17.       EMINENT DOMAIN.

        If the whole of the Premises shall be condemned or taken either
permanently or temporarily for any public or quasipublic use or purpose, under
any statute or by right of eminent domain, or by private purchase in lieu
thereof, then in that event, the term of the Lease shall cease and terminate
from the date of title vesting in such proceeding or purchase and Lessee shall
have no claim against Lessor for the value of any unexpired term of said Lease,
and shall release unto Lessor any such claim it may have against the condemnor
for such value. In the event a portion only of the Premises or a portion of the
Complex containing same shall be so taken (even though the Premises may not have
been affected by the taking of some other portion of the Complex containing
same), Lessor may elect to terminate this Lease




                                      -17-
<PAGE>

from the date of title vesting in such proceeding or purchase, or Lessor may
elect to repair and restore, at its own expense, the portion not taken and
thereafter the rent shall be reduced proportionately to the portion of the
Premises taken. If Lessor elects to terminate in the event of a partial taking
and thereafter restores the Complex and the Premises, Lessee shall have a right
of first refusal to relet the Premises, on substantially the same terms as
herein provided, except that the rental shall be reduced in proportion to the
reduction in the square feet of the Premises and increased by the costs
occasioned by the restoration.

        In the event a substantial portion of the parking area is taken by
condemnation or in lieu thereof, and Lessor does not within thirty (30) days
following the date of the title vesting in such proceeding or purchase take
steps toward providing alternate, nearby parking, Lessee may elect to terminate
this Lease by giving written notice of such intention to Lessor within sixty
(60) days after the date of title vesting in such proceeding or purchase.

        Lessee shall have the right to claim and recover from the condemning
authority such compensation as may be awarded or recoverable by Lessee in its
own right on account of any and all damages to Lessee's improvements, equipment,
property furniture, fixtures, leasehold improvements and the fair market value
of its business; but Lessee's right(s), as stated hereinabove, shall not include
any right to any value attributed to the unexpired term of this Lease if such an
award to Lessee would act to reduce Lessor's award.

SECTION 18.       SUBORDINATION OF LEASE.

        This Lease is and shall remain subordinate and subject to any mortgage
or mortgages which are now or at any time shall be placed upon the freehold
interest of Lessor or any part thereof or to any assignment of the interest of
Lessor in this Lease. Lessee agrees to execute and deliver to Lessor, without
cost, any instrument which may be deemed necessary by Lessor to further effect
the subordination of this Lease to any such mortgage, mortgages or assignments,
except that such instrument shall provide that, so long as Lessee is not in
default hereunder, its possession will not be disturbed nor will its leasehold
interest be divested.

        In the event of a foreclosure of any such mortgage, Lessee hereby agrees
that this Lease shall not terminate by reason thereof, and Lessee further agrees
to attorn to and to recognize as Lessor hereunder the mortgagee, or any
purchaser at a foreclosure sale or any purchaser of the Complex and improvements
in lieu thereof, for the balance of the term of this Lease, subject to all the
terms and provisions



                                      -18-
<PAGE>


hereof provided, however, any such mortgagee or purchaser, which shall become
the Lessor hereunder shall not be:

        (a) liable for any act or omission of Lessor,

        (b) subject to any offsets or defenses which Lessee might have against
Lessor,

        (c) bound by any rent or additional rent which Lessee may have paid to
Lessor for more than the current month, or

        (d) bound by any amendment or modifications of said Lease without its
consent.

SECTION 19.       ESTOPPEL CERTIFICATE.

        Lessee shall, at any time and from time to time, within twenty (20) days
following written request from Lessor, execute, acknowledge and deliver to
Lessor, as supplied by Lessor, a written statement certifying that this Lease is
in full force and effect and unmodified (or, if modified, stating the nature of
such modification), certifying the date to which the rent reserved hereunder has
been paid, and certifying that there are not, to Lessee's knowledge, any uncured
defaults on the part of Lessor hereunder, or specifying such defaults if any are
claimed. Any such statement may be relied upon by any prospective purchaser or
mortgagee of all or any part of the Complex or real property which the Complex
is located. Lessee's failure to deliver such statement within said twenty-day
period shall be conclusive upon Lessee that this Lease is in full force and
effect and unmodified, and that there are no uncured defaults in Lessor's
performance hereunder.

SECTION 20.       FORCE MAJEURE.

        In the event that either party shall be delayed or hindered in, or
prevented from, the performance of any work, service or other acts required
under this Lease to be performed by the party and such delay or hindrance is due
to strikes, lockouts, acts of God, governmental restrictions, enemy act, civil
commotion, unavoidable fire or other casualty, or other causes of a like nature
beyond the control of the party so delayed or hindered, then performance of such
work, service or other act shall be excused for a period of such delay and the
period for the performance of such work, service or other act shall be extended
for a period equivalent to the period of such delay. In no event shall such
delay constitute a termination of this Lease. The provisions of this paragraph
shall not operate to



                                      -19-
<PAGE>


excuse Lessee from the prompt payment of rent, including such pro rata payments
of rent as may be due under Section 20 hereof, after the commencement of the
term. Written notice of any such delays, other than temporary or emergency
interruptions, shall be given to the other party as well as written notice of
the cessation of the same.

SECTION 21.       QUIET ENJOYMENT.

        If Lessee shall pay the rent and perform all its other obligations
hereunder, Lessor covenants that Lessee shall, during the term hereof, enjoy
quiet and peaceable possession of the Premises.

SECTION 22.       ABANDONMENT OF PREMISES.

        If the Premises at any time be deserted or closed, Lessor may enter by
force, without liability or prosecution or action therefore, and may relet the
Premises as Agent of Lessee for any unexpired portion of the term and receive
the rent therefore and apply it on this Lease. In the event Lessor relets the
Premises, Lessor shall remove and store any of Lessee's personal property, at
Lessee's cost.

SECTION 23.       NON-WAIVER.

        The failure or delay on the part of either Lessor or Lessee to enforce
or exercise at any time any of the provisions of this Lease or any of the
irrespective rights or remedies hereunder shall in no way be construed to be a
waiver thereof, nor in any way to affect the validity of this Lease or any part
hereof, or the right of Lessor or Lessee, as the case may be, to thereafter
enforce each and every such provision, right or remedy. No waiver of any breach
of this Lease shall be held to be a waiver of any other or subsequent breach.
The receipt by Lessor of Rent at a time when the Rent is in default under this
Lease shall not be construed as a waiver of such default. The receipt by Lessor
of a lesser amount than the Rent due shall not be construed to be other than a
payment on account of the Rent then due. No act or thing done by Lessor or
Lessor's agents or employees during the term shall be deemed an acceptance or
surrender of a surrender of the Premises, and no agreement to accept such a
surrender shall be valid unless in writing and signed by Lessor.



                                      -20-
<PAGE>

SECTION 24.       NOTICES.

        Any notice or demand required by the provisions of this Lease to be
given to Lessor shall be deemed to have been given adequately if sent by
Certified or Registered Mail to Lessor at the following address: 1220 Frick
Building, Pittsburgh, PA 15219.

        Any notice or demand required by the provisions of this Lease to be
given to Lessee shall be deemed to have been given adequately if sent by
Certified or Registered Mail to Lessee at the following address:

                           Tollgrade Communications, Inc.
                           Harmar Industrial Manor, #101
                           491 Nixon Road
                           Cheswick, PA  15204
                           Attention:  Christian L. Allison

        Either party shall have the right to change its address by giving to the
other party fifteen (15) days' advance written notice of its intention to make
such change and of the substituted address at which any notice or demand may be
directed to it.

SECTION 25.       SUCCESSORS AND ASSIGNS.

        The respective rights and obligations provided in this Lease shall bind
and shall inure to the benefit of the parties hereto, their legal
representative, heirs, successors and assigns; PROVIDED, HOWEVER, that no rights
shall insure to the benefit of any successor of Lessee (excepting, if
applicable, only the personal representative of Lessee's estate), unless
Lessor's written consent for the transfer to such successor has first been
obtained as provided in SECTION 8.

SECTION 26.       ENVIRONMENTAL MATTERS.

        A. For purposes of this Lease:

        (i) As used herein, the term "Environmental Laws" shall mean any and all
federal, state, or local laws, statutes, rules, regulations, ordinances,
interstate compacts, or judicial or administrative decrees, orders, decisions,
or permits relating to emissions, discharges, releases or threatened releases of
pollutants, contaminants or Hazardous Substances into the environment
(including, without limitation, ambient air, surface water, ground water or
subsurface strata); or otherwise relating to the use, storage, treatment,
transportation, manufacture, refinement, handling,



                                      -21-
<PAGE>


production or disposal of such pollutants, contaminants or Hazardous Substances
including, without limitation, the following statutes, as amended and judicially
and administratively interpreted through the date hereof, and all regulations
promulgated thereunder as of such date, including without limitation all
comparable statutes, regulations, and interpretations by the Commonwealth of
Pennsylvania: the Comprehensive Environmental Response, Compensation and
Liability Act, 42 USC 9601 et seq. ("CERCLA"); the Superfund amendments and
Reauthorization Act of 1986, 42 USA ("SARA"); the Federal Water Pollution
Control Act, USC 1251 et seq. ("FWPCA"); the Clean Air Act, 42 USC 7401 et seq.;
the Resource Conservation and Recovery Act, 42 USC 4901 et seq. ("RCRA"); the
Safe Drinking Water Act, 42 SC 300f et seq.; the "Toxic Substance Control Act,
15 USC 2601 et seq.; the Clean Water ACT, 33 U.S.C. 1251 et seq.; the National
Environmental Policy Act 42 U.S.C. 4321 et seq.; the Hazardous Substances
Cleanup Act, 35 Pa. C.S.A. 6020.101 et seq. ("HSCA"); the Clean Streams Law, 35
Pa. C.S.A. 691.1 et seq.; the Solid Waste Management Act, 35 Pa. C.S.A. 6018.101
et seq.; and the Pennsylvania Storage Tank and Spill Prevention Act, Pa Act No.
1989-32; and

        (ii) As used herein, the term "Hazardous Substance" shall mean any and
all elements, compounds, chemical mixtures, contaminants, pollutants, or other
substances identified as "Hazardous Substances" under CERCLA, SARA, or HSCA and
all comparable statutes and regulations, and any used or unused petroleum
products.

        B. Lessee shall:

        (i) Not cause or permit any Hazardous Substance to be placed, held,
located, released, spilled, transported or disposed of on, under, at or from the
Premises or any real estate contiguous thereto in contravention of any
Environmental Laws;

        (ii) Except with respect to matters existing prior to the Commencement
Date, contain at or remove from the Premises or perform any other remedial
action regarding any Hazardous Substance which Lessee has placed on the
Premises, at Lessee's sole cost and expense, if, as and when such containment,
removal or other remedial action is required under any legal requirement;

        (iii) Not permit any subtenant or occupant of the Premises to engage in
any activity that could result in any liability, cost or expense to any such
subtenant, or occupant, Lessee, Lessor or any other owner of the Premises or any
portion thereof or the creation of a lien on the Premises under any
Environmental Laws or under any similar applicable law or regulation;



                                      -22-
<PAGE>



        (iv) Provide Lessor with written notice (and a copy as may be
applicable) of any of the following within ten (10) days thereof:

             (a) Lessee's obtaining actual knowledge or notice of any
             kind of the presence, or any actual or threatened release, of
             any Hazardous Substance on, under, at or from the Premises not
             authorized or permitted under Environmental Laws; (b) Lessee's
             receipt or submission, or Lessee's obtaining actual knowledge or
             notice of any kind, of any report, citation, notice or other
             communication from or to any federal, state or local government
             or quasigovernmental authority regarding any Hazardous Substance
             in any way materially adversely affecting the Premises; or (c)
             Lessee's obtaining actual knowledge or notice of any kind of the
             incurrence of any cost or expense by any federal, state or local
             governmental or quasigovernmental authority or any private party
             in connection with the assessment, monitoring, containment,
             removal or remediation of any kind of any Hazardous Substance
             on, under, at or form the Premises, or of the recording of any
             lien on the Premises in connection with any such action or
             Hazardous Substance on, under or at the Premises; and

        (v) Defend all actions against the Lessor and pay, protect, indemnify
and save harmless the Lessor from and against any and all liabilities, losses
damages, costs, expenses (including, without limitation, reasonable attorneys'
fees and expenses), causes of action, suits, claims, demands or judgments of any
nature arising from Lessee's failure to comply with this SECTION 26. The
indemnity contained in this SECTION 26 shall survive the expiration or earlier
termination of this Lease with respect to the obligations and liabilities of
Lessee hereunder, actual or contingent, which have arisen on or prior to such
expiration or earlier termination.

    C.   Lessor:

        (i) Represents and warrants that to the best of its knowledge no
Hazardous Substances are present on the Premises prior to the Commencement Date;

        (ii) Shall contain at or remove from the Premises or perform any other
remedial action regarding any Hazardous Substance which have been placed on the
Premises prior to the Commencement Date, at Lessor's sole cost and expense,



                                      -23-
<PAGE>


if, as and when such containment, removal or other remedial action is required
under any legal requirement;

        (iii) Shall not permit any tenant or occupant of the Complex to engage
in any activity that could result in any liability, cost or expense Lessee or
any portion thereof or the creation of a lien on the Premises under any
Environmental Laws or under any similar applicable law or regulation;

        (iv) Shall provide Lessee with written notice (and a copy as may be
applicable) of any of the following within ten (10) days thereof:

             (a) Lessor's obtaining actual knowledge or notice of any
             kind of the presence, or any actual or threatened release, of
             any Hazardous Substance on, under, at or from the Premises; (b)
             Lessor's receipt or submission, or Lessor's obtaining actual
             knowledge or notice of any kind, of any report, citation, notice
             or other communication from or to any federal, state or local
             government or quasigovernmental authority regarding any
             Hazardous Substance in any way materially adversely affecting
             the Premises; or (c) Lessor's obtaining actual knowledge or
             notice of any kind of the incurrence of any cost or expense by
             any federal, state or local governmental or quasigovernmental
             authority or any private party in connection with the
             assessment, monitoring, containment, removal or remediation of
             any kind of any Hazardous Substance on, under, at or from the
             Premises, or of the recording of any lien on the Premises in
             connection with any such action or Hazardous Substance on, under
             or at the Premises; and

        (v) Defend all actions against the Lessee and pay, protect, indemnify
and save harmless the Lessee from and against any and all liabilities, losses
damages, costs, expenses (including, without limitation, reasonable attorneys'
fees and expenses), causes of action, suits, claims, demands or judgments of any
nature arising from Lessor's failure to comply with this SECTION 26(c). The
indemnity contained in this SECTION 26(c) shall survive the expiration or
earlier termination of this Lease with respect to the obligations and
liabilities of Lessor hereunder, actual or contingent, which have arisen on or
prior to such expiration or earlier termination.



                                      -24-
<PAGE>

SECTION 27.       GOVERNING LAW.

        This Lease shall be construed, governed and enforced in accordance with
the laws of the Commonwealth of Pennsylvania.

SECTION 28.       SEVERABILITY.

        If any provisions of this Lease shall be held to be invalid, void or
unenforceable, the remaining provisions hereof shall in no way be affected or
impaired and such remaining provisions shall remain in full force and effect.

SECTION 29.       GENDER.

        As used in this Lease, the word "person" shall mean and include, where
appropriate, an individual, corporation, partnership or other entity; the plural
shall be substituted for the singular, and the singular for the plural, where
appropriate; and words of any gender shall mean to include any other gender.

SECTION 30.       OPTION TO RENEW.

        Lessee shall have the right and option to renew this Lease for two (2)
consecutive additional terms for each of five (5) years and two (2) years
following expiration of the term hereof (which renewal terms may be exercised in
whatever order Lessee deems advisable in its sole discretion, e.g., Lessee may
take either the two (2) year term or the five (5) year renewal term immediately
following the expiration of the initial term, and then exercise the remaining
term thereafter), provided: (i) that this Lease is in full force and effect
immediately prior to the date of the commencement of the renewal term; (ii) that
the Lessee is not in default under any of the provisions herein; and (iii) that
Lessee is in full occupancy of the Premises for its own use and intends to
continue such occupancy.

        Such option shall be exercised by Lessee serving on Lessor written
notice to that effect not later than six (6) months prior to the expiration of
the initial term. Said renewal shall be upon the same terms, covenants,
conditions and limitation as in this Lease provided, except that the monthly
rental during the renewal term shall be established at the "going market rate"
for comparably improved space in the greater Pittsburgh market area, but in no
event shall the monthly rental be less that the Base Rent plus Additional Rent
payable to Lessor in the last month of the initial lease term pursuant to
SECTION 3 hereof.



                                      -25-
<PAGE>


        The notice of election to take the renewal term when given by Lessee
shall be irrevocable and shall constitute an agreement between the parties for
renewal of this Lease as herein stated. If this Lease or the right of occupancy
of the Lessee hereunder shall expire, be terminated, or come to an end pursuant
to any of the provisions of this Lease, all rights of Lessee to renew
automatically shall be deemed terminated.

SECTION 31.       ENTIRE AGREEMENT.

        There are no agreements, representations or understandings between the
parties other than those expressed herein. A real estate brokerage commission is
payable by Lessor to The Galbreath Company as a result of consummation of this
agreement. No modification of the terms hereof shall be binding unless set forth
in a writing signed by both parties hereto.

SECTION 32.       LESSOR IMPROVEMENT ADVANCE.

        Lessor shall advance the sum of approximately Fifty Thousand Dollars
($50,000) towards construction of Lessor's Improvements to the Premises
("Lessor's Improvement Advance"), which figure shall be finalized within thirty
(30) days of the date of execution of this Lease, and verified in writing by
Lessor. Lessee shall repay Lessor's Improvement Advance to Lessor in payments
amortized at eight percent (8%) over the term of the Lease. All costs above such
Lessor Improvement Advance shall be paid by Lessee.

SECTION 33.       HVAC SYSTEM.

        Lessor represents that the heating, ventilating and air conditioning
("HVAC") system to serve the Premises, shall provide heating, ventilating and
air conditioning throughout the Premises) as follows:

        (a) Maintain average indoor dry bulb temperatures not less than 70
(degrees)F. during the heating season, whenever the outdoor dry bulb
temperature, during Normal Business Hours, is not lower than 0(degrees)F.
Relative humidity shall be maintained as high as possible without condensations,
but at a range no greater than 40-60% at a room temperature of 75(degrees)F. dry
bulb.

        (b) Maintain average indoor conditions no higher than 78(degrees)F. dry
bulb and at a range of 40-60% relative humidity, during the cooling season,
whenever



                                      -26-
<PAGE>


the outdoor dry bulb temperature, during Normal Business Hours, is not higher
than 95(degrees)F. and the outdoor wet bulb temperature does not exceed 75
(degrees)F.

        (c) The air-handling systems shall be so designed that outside air shall
be introduced into the systems at an average rate of not less than 0.35 cfm per
square foot of usable floor space.

        WITNESS the due execution hereof as of the day and year first above
written.


ATTEST:                                REGIONAL INDUSTRIAL DEVELOPMENT
                                       CORPORATION OF SOUTHWESTERN
                                       PENNSYLVANIA



/s/ Mark Perrm                         BY:    /s/ Frank Brooks Robinson
---------------------------------             ---------------------------------
SECRETARY                              NAME:  Frank Brooks Robinson
                                              ---------------------------------
                                       TITLE: President
                                              ---------------------------------

(Corporate Seal)



ATTEST:                                TOLLGRADE COMMUNICATIONS, INC.



/s/ Richard T. Cassetti                BY:    /s/  Christian L. Allison
---------------------------------             ----------------------------------
                                       NAME:  CHRISTIAN L. ALLISON
                                              ----------------------------------
                                       TITLE: CHIEF OPERATING OFFICER
                                              ----------------------------------



                                      -27-
<PAGE>


                                    EXHIBIT A

                                   FLOOR PLAN



[FLOOR PLAN OF LEASED PREMISES]






                                      -28-
<PAGE>


                                    EXHIBIT B
                              LESSOR'S IMPROVEMENTS
A.       General Items (*to be completed at lessor's expense)

         Clean floors in the printing room area.
         Clean and replace soiled or damaged ceiling tiles and HVAC vents as
         required. Clean area where the hot water heater is located. Clean
         engraving department area and remove ventilation hood. Remove dark room
         door and vent, create archway opening.

B.       Main Office.

         Demo existing office space and add new offices. Reuse doors with glass
         sidelights. Reuse 2'x4' light fixtures. Clean and relamp. New 2' x 4'
         fixtures to be added. New doors are 1 3/4" x 3068 solid oak doors. New
         2'x 4' ceiling tile.
         Twenty-six or twenty-eight ounce commercial carpeting and cove base.
         Electrical outlets, switches, exit lights and emergency lights. Move
         and install existing kitchen unit.
         Add Trol-A-Temp system to handle large meetings in Conference Room.
         Existing HVAC system will be used, with the additional ductwork and
         diffusers for main offices. Township building permit.

C.       Warehouse Office Space.

         Demising wall to separate warehouse is 45' long x 22" high with drywall
         one side. Ceiling tile, 2' x 4' light fixtures and switches. One (1)
         5'0 wide double steel door.
         Paint all walls and cove base drywalls. HVAC will be supplied by
         existing rooftop unit.
         Not included are additional electrical outlets or floor treatment.

D.       Print Shop - Item breakdown.

         Remove 20'0 demising wall and dispose. Cut archway in kitchen wall.
         Patch and paint kitchen walls. Clean VCT in offices and hallway.
         Paint hallway, composition room, file room and bathrooms. Paint doors
         and frames. Paint walls in print shop.
         Seal floors in print shop. Relamp and clean fixtures in print shop. New
         ballast for light fixtures.


                                      -29-