<PAGE>   1


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-K

[X]   ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
      ACT OF 1934

                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 2000
                         COMMISSION FILE NUMBER 0-27312

                         TOLLGRADE COMMUNICATIONS, INC.
             (Exact name of registrant as specified in its charter)

            PENNSYLVANIA                                           25-1537134
   (State or other jurisdiction of                           (I.R.S. Employer
   incorporation or organization)                           Identification No.)

   493 NIXON ROAD, CHESWICK, PENNSYLVANIA                           15024
   (Address of principal executive offices)                       (Zip Code)

Registrant's telephone number, including area code: 412-820-1400

           SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:

                     COMMON STOCK, PAR VALUE $.20 PER SHARE
                                (Title of Class)

Indicate by a check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registration was required to file such reports), and (2) has been subject to
such filing requirements for the past 90 days.
Yes   X      No
    -----       -----

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of Registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K.  X
          -----

The Registrant estimates that as of March 7, 2001, the aggregate market value of
shares of the Registrant's Common Stock held by non-affiliates (excluding for
purposes of this calculation only, 179,033 shares of Common Stock held of record
or beneficially by the executive officers and directors of the Registrant as a
group) of the Registrant was $324,406,770.

As of March 7, 2001, the Registrant had outstanding 13,352,912 shares of its
Common Stock.

                       DOCUMENTS INCORPORATED BY REFERENCE

                                                   Parts of Form 10-K into which
Document                                              Document is incorporated

Portions of the Annual Report to Shareholders
 for the year ended December 31, 2000                        II and IV

Portions of the Proxy Statement to be distributed
 in connection with the 2001 Annual
 Meeting of Shareholders                                        III


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                                     PART I

CAUTIONARY STATEMENT FOR PURPOSES OF THE "SAFE HARBOR" PROVISIONS OF THE PRIVATE
SECURITIES LITIGATION REFORM ACT OF 1995.

The statements contained in this Annual Report on Form 10-K, specifically those
contained in Item 1 Business and Item 7 Management's Discussion and Analysis of
Financial Condition and Results of Operation, and statements incorporated by
reference into this Form 10-K from the 2000 Annual Report to Shareholders, along
with statements in other reports filed with the Securities and Exchange
Commission, external documents and oral presentations, which are not historical
are forward-looking statements within the meaning of Section 27A of the
Securities Act of 1933, as amended, and Section 21E of the Securities Exchange
Act of 1934, as amended. These forward-looking statements represent Tollgrade
Communications, Inc.'s (the "Company") present expectations or beliefs
concerning future events. The Company cautions that such statements must be
qualified by important factors that could cause actual earnings and other
results to differ materially from those achieved in the past or those expected
by the Company. These statements as to management's beliefs, strategies, plans,
expectations or opinions in connection with Company performance, are based on a
number of assumptions concerning future conditions that may ultimately prove to
be inaccurate. Such statements must be qualified by important factors that could
cause actual earnings and other results to differ materially from those achieved
in the past or those expected by the Company. These include: customers' ability
to meet established purchase forecasts and their own growth projections; the
ability of certain customers to maintain financial strength and access to
capital; the ability for sales and marketing partners to meet their own
performance objectives and provide vendor financing to certain local exchange
carriers; customer's seasonal buying patterns and the risk of order
cancellations; risk of shortage of key components and possibility of limited
source of supply; manufacturing delays and availability of manufacturing
capacity; intense competition in the market for the Company's products; rapid
technological change along with the need to continually develop new products and
gain customer acceptance and approval; the Company's dependence on a relatively
narrow range of products; competition; the Company's dependence on key
employees; difficulties in managing the Company's growth; the Company's
dependence upon a small number of large customers and certain suppliers; the
Company's dependence upon proprietary rights; risks of third party claims of
infringement; possibility of product defects; and government regulation. The
Company does not undertake any obligation to publicly update any forward-looking
statements.

ITEM 1. BUSINESS.

         The Company was incorporated in Pennsylvania in 1986 and began
operations in 1988. Its principal offices are located at 493 Nixon Road,
Cheswick, Pennsylvania 15024 and its telephone number is (412) 820-1400.

         The Company designs, engineers, markets and supports test system, test
access and status monitoring products for the telecommunications and cable
television industries. The Company's telecommunications proprietary test access
products enable telephone companies to use their existing line test systems to
remotely diagnose problems in "Plain Old Telephone Service" ("POTS") lines
containing both copper and fiber optics. POTS lines comprise the vast majority
of lines in service today throughout the world. In addition to traditional voice
service, POTS includes lines for popular devices such as computer modems and fax
machines. POTS excludes the more complex lines, such as data communications
service lines, commonly referred to as "special services."

         In general, POTS line test systems, which are located at telephone
companies' central offices, focus on helping local exchange carriers conduct the
full range of fault diagnosis in the "local loop", which


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is the portion of the telephone network which connects end users to a telephone
company's central office. In addition, these line test systems have the ability
to remotely qualify, deploy and maintain next generation services that include
Digital Subscriber Line ("DSL") service and Integrated Services Digital Network
("ISDN") service. These test systems reduce the time needed to identify and
resolve problems and eliminate or reduce the cost of dispatching a technician to
the problem site. Most POTS line test systems were designed for use over copper
wireline only, so that the introduction of fiber-optic technology into the local
loop renders it inaccessible to these test systems. The Company's metallic
channel unit ("MCU"(R)) products solve this problem by extending test-system
access through the fiber-optic portion into the copper portion of the local
loop. In addition, the Company's DigiTest(R) system is designed to provide
complete hardware testing for POTS and local loop prequalification and
in-service testing for DSL service.

         The Company's LIGHTHOUSE(R) cable status monitoring system provides a
broad testing solution for the Broadband Hybrid Fiber Coax distribution system
found in the cable television industry. This status monitoring system gathers
status information and reports on strategic components within the cable network.

         Products. The Company's MCU products plug into the digital loop carrier
("DLC") systems that are large systems manufactured by equipment vendors such as
Lucent (formerly part of AT&T), that are used by telephone companies to link the
copper and fiber-optic portions of the local loop. DLC systems are located at
the telephone company central offices and at remote sites within a local user
area, and effectively multiplex the services of the copper lines into a single
fiber-optic line. In many instances, several DLC systems are located at a single
remote site to serve several thousand different end-user homes and offices.
Generally, for every DLC remote site, at least two MCU line-testing products are
deployed. To ensure compatibility of the MCU with these DLC systems, the Company
pays royalties pursuant to license agreements for the use of proprietary design
integrated circuits ("PDICs"). The PDICs are the design and property of the DLC
system manufacturer from which they are purchased. The Company maintains license
agreements with and pays royalties to Lucent Technologies, Fujitsu Network
Transmission Systems, Inc., NEC America, Inc. and Reliance Comm/Tec Corporation.
In general, the current terms for expiration of these agreements range at
various times between August 2001 and an indefinite duration, with renewal
provisions (unless earlier terminated) for periods of between one and five
years. In addition, certain of these agreements can be terminated prior to
renewal. The Company incurred $1,904,000, $2,012,000 and $2,507,000 respectively
in 1998, 1999 and 2000 as royalties under the license agreements, which
royalties are calculated either based on a percentage of the list price of the
MCU products or a fixed amount per unit that incorporates the technology
licensed under each such agreement. Certain of the license agreements require
the Company to maintain the confidentiality of the licensor's proprietary
information and/or the terms and conditions of the agreement itself. In
addition, the Company maintains license agreements that do not contain royalty
provisions with Advanced Fibre Communications, Alcatel USA Sourcing, L.P.
(formerly DSC Technologies Corporation), Northern Telecom Inc., UTSTARCOM, Inc.,
Next Level Communications and SAGEM SA (a French corporation). The expiration
dates of these agreements range at various times between May 2001 and November
2004, with renewal provisions (unless earlier terminated) for periods of one or
more years. Future license agreements entered into by the Company may contain
terms comparable to, or materially different than, the terms of existing
agreements as competitive and other conditions warrant. The loss of PDICs
license agreements or the inability of the Company to maintain an adequate
supply of PDICs could have a material adverse effect on the Company's business.
Other MCU technology is also used with home and business alarm systems. As with
home service line testing, home alarm systems must be monitored from the alarm
company's headquarters along a hybrid copper and fiber-optic line. The Company's
alarm-related MCU products are used to facilitate the transport of analog alarm
signals from subscriber homes to alarm company monitoring stations across the
hybrid telephone network. These units plug into equipment at both central office
and remote locations. MCU products and related hardware accounted for more than
90%, 74% and 70% of the Company's sales in 1998, 1999 and 2000, respectively.


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         The Company's next-generation DigiTest centralized network test
platform provides a system solution for providing service assurance needs POTS
and ISDN service. In addition, the DigiTest system provides a full range of
features that enable local exchange carriers to prequalify and maintain their
networks for DSL service. The DigiTest product line is designed to work in
conjunction with the major Operation Support System ("OSS") equipment
manufacturers. The DigiTest system serves as an integral component of those OSS
systems that allow for request and retrieval of precise measurement results that
form the basis for state-of-the-art fault diagnosis for both traditional
narrowband and wideband applications. DigiTest's compact digital measurement
unit ("DMU") which resides in the central office, acts as the test head in the
test system, with the ability to determine subscriber line characteristics with
network diagnostic functions including load coil detection, loop length
measurement and longitudinal balance for Single-Ended Loop Qualification
("SELQ"). DigiTest's digital wideband unit ("DWU") next-generation testing
platform enables single-ended loop qualification by identifying and locating
bridged taps and measuring crosstalk and wideband noise, all important factors
in the prequalification and in-service maintenance of local loops for DSL
service. The DigiTest system also includes the Digital Measurement Node ("DMN"),
which consists of a metal-chassis, backplane and an alarm/fuse card which is
used to house the DMU and DWU. To ensure interoperability with these OSS
systems, the Company pays royalties pursuant to license agreements for the use
of certain network interface information to Lucent Technologies and Nortel
Networks Corporation. In general, the current terms for expiration of these
agreements range at various times between July 2002 and September 2003, with
renewal provisions (unless earlier terminated) for a period of one year. The
Company incurred $0, $116,000 and $404,000 respectively in 1998, 1999 and 2000
as royalties under the license agreements, which royalties are calculated based
on a percentage of the sale price of the DMU and certain DWU units that
incorporate the technology licensed under such agreements. The license
agreements require the Company to maintain the confidentiality of the licensor's
proprietary information and/or the terms and conditions of the agreement itself.
The Company markets and sells its DigiTest products directly as well as through
certain OEM arrangements with Lucent Technologies and Nortel Networks
Corporation.

         The Company's cable products consist of a complete cable status
monitoring system that provides a comprehensive testing solution for the
Broadband Hybrid Fiber Coax distribution system. The status monitoring system
consists of a host for user interface, control and configuration; a headend
controller for managing network communications; and transponders that are
strategically located within the cable network to gather status reports from
power supplies, line amplifiers and fiber-optic nodes. The Company has entered
into a license agreement with C-COR.net Corp. (formerly C-COR Electronics, Inc.;
a cable television systems developer) in which the Company provides its status
monitoring transponder technology that is incorporated into C-COR's cable
network management system. The Company, under certain other business
arrangements, also markets and sells its cable products directly as well as
through various OEM customers such as ANTEC and Motorola (formerly General
Instrument).

         Product and Technology Development. The Company's product development
personnel are organized into teams, each of which is effectively dedicated to a
specific product line(s) or technology. Each product team also implements the
Company's ongoing value engineering programs that are designed to replace the
Company's products with successive generations having additional features and/or
lower costs. The Company continuously monitors developing technologies in order
to introduce products as defined standards and markets emerge. In addition, the
Company continues to investigate the development of new applications for its MCU
technology and other technologies to service the telecommunications industry.
During 1998, 1999 and 2000, research and development expenses were approximately
$6,880,000, $8,757,000 and $12,456,000, respectively.

             Proprietary Rights. The names "Tollgrade(R)", "MCU(R)",
"LIGHTHOUSE(R)", "DigiTest (R)", "Telaccord(R)" and "MICRO-BANK(R)", and the
Company's corporate logo are registered trademarks of the


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Company. "Team Tollgrade(SM)" is a service mark of the Company. The Company has
obtained three United States patents on the MCU products with expiration dates
ranging from 2010 to 2014 and a United States patent on a cable product that
expires in 2016. In addition, the Company has one U.S. provisional, six United
States, three Canada and one international patent cooperation treaty ("PCT")
patent applications pending. The Company will seek additional patents from time
to time related to its research and development activities. The Company protects
its trademarks, patents, inventions, trade secrets, and other proprietary rights
by contract, trademark, copyright and patent registration, and internal
security.

         Customers. The Company's primary telecommunication customers are the
four regional Bell operating companies ("RBOCs"), which are Verizon
Communications, BellSouth Corporation, SBC Communications Inc., and Qwest Inc.,
as well as major independent telephone companies. Sales in 2000 to Verizon
Communications, BellSouth Corporation, SBC Communications, Inc., and Qwest
Communications Corp. accounted for approximately 11%, 14%, 29% and 10%,
respectively of total revenues. In addition, sales to Sprint USA accounted for
approximately 12% of the Company's sales in 2000. The Company's primary cable
products are sold on a direct basis as well as to certain cable Original
Equipment Manufacturer ("OEM") customers such as C-COR.net Corp., ANTEC
Corporation and Motorola, Inc. (formerly General Instrument). Sales of the
Company's cable products in 2000 were approximately 9% of total revenues. The
Company's relationships with its customers are material to the Company's
business, and the loss of any such relationship could have a material adverse
effect on the Company's business.

         Manufacturing. The Company's manufacturing operations consist primarily
of quality control, functional testing, final assembly, burn-in and shipping.
The Company is ISO 9001 registered from the British Standards Institution, Inc.
ISO 9000 is a harmonized set of standards that define quality assurance
management. Written by the International Organization for Standardization (ISO),
it is recognized throughout the United States, Canada, the European Union and
Japan. To be registered, the Company develops and maintains internal
documentation and processes to support the production of quality products to
ensure customer satisfaction. The Company utilizes two key independent
subcontractors to perform a majority of the circuit board assembly and
in-circuit testing work on its products. The Company also utilizes other
subassembly contractors on a more limited basis. The loss of the subcontractors
could cause delays in the Company's ability to meet production obligations and
could have a material adverse effect on the Company's results of operations. In
addition, shortages of raw material to, or production capacity constraints at,
the Company's subcontractors could negatively affect the Company's ability to
meet its production obligations and result in increased prices for affected
parts. Any such reduction may result in delays in shipments of the Company's
products or increases in the price of components, either of which could have a
material adverse impact on the Company.

         The Company currently procures all of its components from outside
suppliers. Generally, the Company uses industry standard components for its
products. Application specific integrated circuits (ASICs) are a key component
to the manufacturing process and are custom made to the Company's
specifications. Although the Company has generally been able to obtain ASICs on
a timely basis, a delay in the delivery of these components could have a
material adverse impact on the Company.

         Backlog. The Company's backlog at December 31, 2000 was approximately
$8.2 million, as compared to approximately $12.1 million at December 31, 1999.
The Company's backlog consists of firm customer purchase orders for the
Company's various products. The backlog at December 31, 2000 includes a one-time
order from Qwest of approximately $1.3 million related to the Company's
Broadcast Program Channel Unit, which will be used for the Salt Lake City Winter
Olympic Games. Periodic fluctuations in customer orders and backlog result from
a variety of factors, including but not limited to the timing of significant
orders and shipments. While these fluctuations could impact short-term results,
they are not necessarily indicative of long-term trends in sales of the
Company's products.


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         Competitive Conditions. The market for telecommunications and cable
television equipment is highly competitive. The deciding competitive factors in
the Company's market include price, product features, performance, reliability,
service and support, breadth of product line, technical documentation and prompt
delivery. The Company believes that it competes favorably on all of these
factors, and certain of its products have proprietary or patented features. The
Company also attempts to enter into development agreements for its MCU products
with the manufacturers of DLC and other complex systems, which serves to ensure
compatibility for its products. Competition would increase if new companies
enter the Company's product markets or existing competitors expand their product
lines. For instance, the telecommunications reform legislation has lifted the
restrictions that previously prevented the RBOCs from manufacturing
telecommunications equipment. Pursuant to this legislative reform, the RBOCs,
which are the Company's largest customers, may become competitors of the Company
in the markets served by the Company.

         For the Company's line-testing MCU devices, the primary competitive
technologies are the remote monitoring units made by Teradyne, Inc. and the
Harris Communications Product Division of Harris Communications, Inc. In
addition, the Anritsu Wiltron Test and Measurement Group, a division of Anritsu
Corporation, offers the Wiltron LoopMATE, a modular remote test head, which
competes with the Company's POTS testing capabilities. The Company believes the
MCU is simpler and less costly to install and permits the full complement of
centralized testing to be performed as quickly and accurately as with copper
by-pass wiring. The alarm-related MCU product's primary competitor is the Turbo
2000 unit made by ANTEC Corporation. The primary competitors for the Company's
DigiTest product line include Harris Corporation, Hekimian Laboratories and
Turnstone Systems, Inc. For the Company's cable products, the primary
competitors for status monitoring are Acterna Corporation and AM Communications,
Inc.

         Employees. At December 31, 2000, the Company had 411 full-time
employees, all in the United States. None of the Company's employees are
represented by a collective bargaining agreement.

         Government Regulation. The telecommunications industry is subject to
regulation in the United States and other countries. Federal and state
regulatory agencies, including the FCC and various state public utility
commissions and public service commissions, regulate most of the Company's
domestic customers. While such regulation does not typically affect the Company
directly, the effects of such regulations on the Company's customers may, in
turn, adversely impact the Company's business and operating results.
Governmental authorities also have promulgated regulations which, among other
things, set installation and equipment standards for private telecommunications
systems and require that all newly installed hardware be registered and meet
certain government standards.

ITEM 2.  PROPERTIES.

         The Company's headquarters and principal administrative, engineering,
manufacturing, warehouse and maintenance facilities are located in Cheswick,
Pennsylvania. The Company occupies 100% of the approximate 111,600 square foot
facility. The Company occupies its current facilities under a lease that expires
in December 2002 with an option to renew the term of the lease for one
additional period of three years. The Company has recently completed a facility
occupancy and planning study to determine the various alternatives available for
facility expansion that may be necessary to accommodate potential future growth.
The Company is currently evaluating these alternatives that include the
solicitation and potential procurement of certain land parcels that surround the
current leased facility for the possible expansion of parking and/or new
building structures that the Company believes will provide adequate space to
support future operations and sales growth, if necessary.


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ITEM 3.  LEGAL PROCEEDINGS.

         There are currently no outstanding or pending material legal
proceedings with respect to the Company or its business.


ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

         During the fourth quarter of 2000, there were no matters submitted to a
vote of security holders through solicitation of proxies or otherwise.


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                        EXECUTIVE OFFICERS OF THE COMPANY

Information relating to the executive officers of the Company as of January 31,
2001 is set forth below:


Christian L. Allison       Chairman of the Board since April 1998; Chief
                           Executive Officer since September 1995; also
                           Treasurer from May 1992 until April 1997; also
                           Secretary from May 1992 until April 1996; also
                           President from October 1993 until January 2001;
                           Age 39.

Sara M. Antol              General Counsel since December 2000; Secretary since
                           April 1996; Chief Counsel from April 1996 until
                           December 2000; prior thereto, employed by the law
                           firm of Babst, Calland, Clements and Zomnir, P.C.;
                           Age 39.

Richard A. Bair, Jr.       Executive Vice President, Engineering/Testing since
                           August 2000; Vice President Engineering, DigiTest
                           from June 2000 until August 2000; Engineering Manager
                           from April 1999 until August 2000; Senior Design
                           Engineer from March 1996 until April 1999; Design
                           Engineer from March 1995 until March 1996; Age 38.

Robert L. Cornelia         Executive Vice President, Operations since May 1996;
                           prior thereto, Vice President, Manufacturing; Age 38.

Bradley N. Dinger          Controller since September 1996; prior thereto,
                           Assistant Controller of AMSCO International, Inc.
                           (manufacturer of health care equipment); Age 38.

Rocco L. Flaminio          Vice Chairman and Chief Technology Officer; Executive
                           Vice President; Age 76.

Mark C. Frey               Senior Vice President, Access Products; Age 47.

Samuel C. Knoch            Chief Financial Officer since August 1996; Treasurer
                           since April 1997; Controller of AMSCO International,
                           Inc. (manufacturer of health care equipment) from
                           October 1994 until August 1996; Age 44.

Joseph G. O'Brien          Senior Vice President, Human Resources since October
                           1997; Director of Employee Development from April
                           1997 until October 1997; Coordinator, Elderberry
                           Junction, Goodwill Industries (a charitable
                           organization) from May 1995 until April 1997; Age 41.

Timothy D. O'Brien         Director of Corporate Communications since August
                           1997; Vice President of Ketchum Public Relations (a
                           public relations firm) from November 1995 until
                           August 1997; prior thereto, Account Supervisor at
                           Ketchum; Age 40.

Mark B. Peterson           President since January 2001; Executive Vice
                           President, Sales and Marketing from November 1999
                           until January 2001; Executive Vice


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                           President, Sales from October 1997 until November
                           1999; prior thereto, Testing Application Group
                           product manager (MLT and Switched Access Remote Test
                           Systems (SARTS) product lines) of Lucent Technologies
                           (a manufacturer of communication systems, software
                           and products and formerly AT&T Bell Laboratories)
                           from October 1995 until October 1997; Age 40.

Matthew J. Rosgone         Senior Vice President, Purchasing/Manufacturing since
                           July 1998; Vice President, Purchasing from July 1996
                           until July 1998; Director of Purchasing from July
                           1995 until July 1996; prior thereto, Buyer; Age 32.

Roger A. Smith             Executive Vice President, Technology since June 2000;
                           Senior Vice President, Test Systems from July 1998
                           until June 2000; Engineering Manager from June 1997
                           until July 1998; Senior Software Engineer from June
                           1996 until June 1997; prior thereto, Senior Software
                           Development Engineer of Caldon Inc. (a manufacturer
                           of ultrasonic flow meters for nuclear power
                           industry); Age 40.


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                                     PART II

ITEM 5.  MARKET FOR THE REGISTRANT'S COMMON STOCK AND RELATED SECURITY HOLDER
         MATTERS.

         Information relating to the market for the Company's Common Stock and
other matters related to the holders thereof is set forth under the caption
"Common Stock Market Price" on page 27 of the Company's 2000 Annual Report to
Shareholders and is incorporated herein by reference.

ITEM 6.  SELECTED FINANCIAL DATA.

         A summary of selected financial data for the Company, including each of
the last five fiscal years in the period ended December 31, 2000, is set forth
under the caption "Selected Consolidated Financial Data" on page 6 of the
Company's 2000 Annual Report to Shareholders and is incorporated herein by
reference.


ITEM 7.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
         RESULTS OF OPERATIONS.

         A discussion of the Company's financial condition and results of
operations is set forth under the caption "Management's Discussion and Analysis
of Financial Condition and Results of Operations" on pages 7 through 13 of the
Company's 2000 Annual Report to Shareholders and is incorporated herein by
reference.


ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA.

         The Company's consolidated financial statements, together with the
report thereon of PricewaterhouseCoopers LLP, are set forth on pages 15 through
26 of the Company's 2000 Annual Report to Shareholders and are incorporated
herein by reference. Such financial statements and supplementary data are listed
in Part IV Item 14(a) (1), Exhibits, Financial Statement Schedules, and Reports
on Form 8-K.


ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
         FINANCIAL DISCLOSURE.

         None.



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                                    PART III

ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT.

         In addition to the information reported in Part I of this Form 10-K,
under the caption "Executive Officers of the Company," the information required
by this item appears beneath the caption "Election of Directors" in the
Company's definitive Proxy Statement for its 2001 Annual Meeting of Shareholders
and is incorporated herein by reference.

ITEM 11.  EXECUTIVE COMPENSATION.

         Information relating to executive compensation is set forth beneath the
caption "Executive Compensation" in the Company's definitive Proxy Statement for
its 2001 Annual Meeting of Shareholders and is incorporated herein by reference.


ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT.

         Information relating to the security ownership of beneficial owners of
5% or more of the Common Stock and of the executive officers and directors of
the Company is set forth under the caption "Stock Ownership of Management and
Certain Beneficial Owners" in the Company's definitive Proxy Statement for its
2001 Annual Meeting of Shareholders and is incorporated herein by reference.


 ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS.

         Information relating to certain relationships and related transactions
is set forth beneath the caption "Certain Relationships and Related
Transactions" in the Company's definitive Proxy Statement for its 2001 Annual
Meeting of Shareholders and is incorporated herein by reference.

                                     PART IV

ITEM 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K.

(a)(1) The following financial statements and supplementary data are
incorporated in Item 8 of Part II of this Form 10-K by reference to pages 14
through 27 of the Company's 2000 Annual Report to Shareholders, which are
incorporated herein by reference:

         Statement of Management's Responsibility for Financial Reporting,
         dated January 19, 2001

         Report of Independent Accountants, dated January 19, 2001

         Consolidated Balance Sheets at December 31, 1999 and 2000

         Consolidated Statements of Operations for each of the three years in
         the period ended December 31, 2000

         Consolidated Statements of Changes in Shareholders' Equity for each
         of the three years ended December 31, 2000

         Consolidated Statements of Cash Flows for each of the three years
         ended December 31, 2000

         Notes to Consolidated Financial Statements

         Statements of Operations Data by Quarter

(a)(2) The following financial statement schedule is included herewith on page
16 and made a part hereof:

         Schedule II (Valuation and Qualifying Accounts)


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(a)(3)  The following exhibits are included herewith and made a part hereof:

Exhibit
Number                                  Description
-------                                 -----------

 3.1     Amended and Restated Articles of Incorporation of the Company, as
         amended through May 6, 1998 (conformed copy), filed as Exhibit 3.1 to
         the Annual Report of Tollgrade Communications, Inc. on Form 10-K for
         the year ended December 31, 1998 (the "1998 Form 10-K").

 3.1a    Statement with Respect to Shares dated July 23, 1996 (conformed copy),
         filed as Exhibit 3.1a to the 1998 Form 10-K.

 3.2     Amended and Restated Bylaws of the Company, filed as Exhibit 3.2 to the
         Report on Form 10-Q of the Company filed on August 10, 1999 and
         incorporated herein by reference thereto.

 4.1     Rights Agreement, dated as of July 23, 1996 between the Company and
         Chase Mellon Shareholder Services, L.L.C., filed as Exhibit 1 to the
         Company's Registration Statement on Form 8-A and incorporated herein by
         reference thereto.

10.1     Common Stock Purchase Agreement dated November 7, 1994, between the
         Company and the investors listed on Schedule A thereto (attachments and
         exhibits omitted), filed as Exhibit 10.1 to the Company's Registration
         Statement on Form S-1 (the "S-1") and incorporated herein by reference
         thereto.

10.2*    1995 Long-Term Incentive Compensation Plan, amended and restated as of
         January 5, 2001, filed as Exhibit B to the Company's 2001 Proxy
         Statement and incorporated herein by reference thereto.

10.3     License Agreement, dated August 24, 1993 between Fujitsu Network
         Transmission Systems, Inc. and the Company, filed as Exhibit 10.4 to
         the S-1 and incorporated herein by reference thereto.

10.4     License Agreement, dated September 26, 1994 between NEC America, Inc.
         and the Company, filed as Exhibit 10.5 to the S-1 and incorporated
         herein by reference thereto.

10.5     Interface License Agreement, dated March 22, 1995 between Northern
         Telecom Inc. and the Company, filed as Exhibit 10.7 to the S-1 and
         incorporated herein by reference thereto.

10.6     Technical Information Agreement, dated February 1, 1993 between
         American Telephone and Telegraph Company and the Company, filed as
         Exhibit 10.8 to the S-1 and incorporated herein by reference thereto.

10.7     Technology License Agreement, dated November 16, 1994 between DSC
         Technologies Corporation and the Company, filed as Exhibit 10.12 to the
         S-1 and incorporated herein by reference thereto.


                                       12
<PAGE>   13

10.8     License Agreement, dated August 24, 1993 between Reliance Comm/Tec
         Corporation and the Company, filed as Exhibit 10.13 to the S-1 and
         incorporated herein by reference thereto.

10.9*    Employment Agreement, dated as of December 13, 1995, between the
         Company and Christian L. Allison, filed as Exhibit 10.11 to the Annual
         Report of the Company on Form 10-K for the year ended December 31, 1995
         (the "1995 Form 10-K").

10.10*   Stock Option Agreement entered into December 14, 1995 between the
         Company and R. Craig Allison, together with a schedule listing
         substantially identical agreements with Gordon P. Anderson, Jeffrey
         Blake, John H. Guelcher, Richard H. Heibel, Joseph T. Messina and
         Douglas T. Halliday, filed as Exhibit 10.14 to the 1995 Form 10-K.

10.11*   Form of Stock Option Agreement dated December 14, 1995 and December 29,
         1995 for Non-Statutory Stock Options granted under the 1995 Long-Term
         Incentive Compensation Plan, filed as Exhibit 10.15 to the Annual
         Report of the Company on Form 10-K for the year ended December 31, 1996
         (the "1996 Form 10-K").

10.12*   Form of Stock Option Agreement for Non-Statutory Stock Options granted
         under the 1995 Long-Term Incentive Compensation Plan, filed as Exhibit
         10.2 to the Report on Form 10-Q of the Company filed on November 12,
         1996.

10.13*   Form of Non-employee Stock Option Agreement entered into December 13,
         1996 and December 30, 1997 between the Company and Lawrence Arduini,
         filed as Exhibit 10.19 to the 1996 Form 10-K.

10.14*   Amendment to Employment Agreement, dated as of December 13, 1996,
         between the Company and Christian L. Allison, filed as Exhibit 10.20 to
         the 1996 Form 10-K.

10.15*   Amendment to Employment Agreement, dated as of December 13, 1997,
         between the Company and Christian L. Allison, filed as Exhibit 10.21 to
         the Annual Report of the Company on Form 10-K for the year ended
         December 31, 1997 (the "1997 Form 10-K").

10.16    Amendment, dated February 21, 1997, to Technical Information Agreement
         relating to Metallic Channel Units Types A and B, dated February
         1,1993, between American Telephone and Telegraph Company (AT&T)
         (licensor) and the Company (licensee) incorporated by reference to
         Exhibit 10.3 to the Report on Form 10-Q of the Company filed on
         November 10, 1997.

10.17*   Form of Non-employee Director Stock Option Agreement with respect to
         the Company's 1995 Long-Term Incentive Compensation Plan, filed as
         Exhibit 10.25 to the 1997 Form 10-K.

10.18*   Amendment to Employment Agreement, dated as of December 30, 1998,
         between the Company and Christian L. Allison, filed as Exhibit 10.28 to
         the 1998 Form 10-K.

10.19*   Amendment to Employment Agreement, dated as of January 18, 2000,
         between the Company and Christian L. Allison, filed as Exhibit 10.25 to
         the 1999 Form 10-K.


                                       13
<PAGE>   14

10.20*   Change in Control Agreement, entered into February 9, 2000 between the
         Company and Sara M. Antol, together with a schedule listing
         substantially identical agreements with Robert Cornelia, Ruth Dilts,
         Bradley Dinger, Rocco Flamino, Mark Frey, Samuel Knoch, James Price,
         and Matthew Rosgone, filed as Exhibit 10.26 to the 1999 Form 10-K.

10.21*   Change in Control Agreement, entered into December 20, 1999 between the
         Company and Scott Robbins, filed as Exhibit 10.27 to the 1999 Form
         10-K.


10.22*   Change in Control Agreement, entered into August 10, 2000 between the
         Company and Stephen M. Garda, filed as Exhibit 10.30 to the Report on
         Form 10-Q of the Company filed on November 13, 2000.

10.23*   Amendment to Employment Agreement, dated as of January 3, 2001, between
         the Company and Christian L. Allison, filed herewith.

10.24*   Change in Control Agreement, entered into January 19, 2001 between the
         Company and Joseph G. O'Brien, together with a schedule listing
         substantially identical agreements with Lawrence J. Fey, William J.
         Gumbert, Gary L. Gump, Michael D. McSparrin, Timothy D. O'Brien, Mark
         B. Peterson, Roger A. Smith and Jeffrey J. Tatusko, filed herewith.

10.25*   1998 Employee Incentive Compensation Plan, amended and restated as of
         December 14, 2000, filed herewith.

13.1     Company's 2000 Annual Report to Shareholders, filed herewith.

21.1     List of subsidiaries of the Company, filed as Exhibit 21.1 to the S-1
         and incorporated herein by reference thereto.

23.1     Consent of PricewaterhouseCoopers LLP, filed herewith.

27       Financial Data Schedule.

* Management contract or compensatory plan, contract or arrangement required
  to be filed by item 601(b)(10)(iii) of Regulation S-K.

         The Company agrees to furnish to the Commission upon request copies of
all instruments not listed above which define the rights of holders of long-term
debt of the Company.

         Copies of the exhibits filed as part of this Form 10-K are available at
a cost of $.20 per page to any shareholder of record upon written request to the
Secretary, Tollgrade Communications, Inc., 493 Nixon Road, Cheswick,
Pennsylvania 15024.

(b)  Reports on Form 8-K filed during the quarter ended December 31, 2000.

             None.


                                       14
<PAGE>   15

                                   SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange
Act of 1934, the Company has duly caused this report to be signed on its behalf
by the undersigned, thereunto duly authorized as of March 23, 2001.

                                        TOLLGRADE COMMUNICATIONS, INC.


                                        By /s/Christian L. Allison
                                           -------------------------------------
                                           Christian L. Allison
                                           Chairman and Chief Executive Officer


         Pursuant to the requirements of the Securities Exchange Act of 1934,
this report has been signed below by the following persons on behalf of the
Company and in the capacities indicated as of March 23, 2001.


           SIGNATURE                                  TITLE

 /s/Christian L. Allison                      Director, Chairman and
---------------------------------------       Chief Executive Officer,
    Christian L. Allison                      (Principal Executive Officer)


/s/James J. Barnes                            Director
---------------------------------------
    James J. Barnes

/s/Daniel P. Barry                            Director
---------------------------------------
    Daniel P. Barry

/s/David S. Egan                              Director
---------------------------------------
    David S. Egan

  /s/Rocco L. Flaminio                        Director, Vice Chairman
---------------------------------------       and Chief Technology Officer
    Rocco L. Flaminio


  /s/ Richard H. Heibel, M.D.                 Director
---------------------------------------
    Richard H. Heibel, M.D.


 /s/Robert W. Kampmeinert                     Director
---------------------------------------
    Robert W. Kampmeinert


/s/Samuel C. Knoch                            Chief Financial Officer
---------------------------------------       and Treasurer
    Samuel C. Knoch                           (Principal Financial Officer)


/s/Bradley N. Dinger                          Controller
---------------------------------------       (Principal Accounting Officer)
    Bradley N. Dinger


                                       15
<PAGE>   16

                     Report of Independent Accountants on
                          Financial Statement Schedule



To the Board of Directors
Tollgrade Communications, Inc.:

Our audits of the consolidated financial statements referred to in our report
dated January 19, 2001 appearing in the 2000 Annual Report to Shareholders of
Tollgrade Communications, Inc. (which report and consolidated financial
statements are incorporated by reference in this Annual Report on Form 10-K)
also included an audit of the financial statement schedule listed in Item
14(a)(2) of this Form 10-K. In our opinion, this financial statement schedule
presents fairly, in all material respects, the information set forth therein
when read in conjunction with the related consolidated financial statements.


/s/ PRICEWATERHOUSECOOPERS LLP


Pittsburgh, Pennsylvania
January 19, 2001



                                       16
<PAGE>   17
                                                                    SCHEDULE II


                 TOLLGRADE COMMUNICATIONS, INC. AND SUBSIDIARIES

                        VALUATION AND QUALIFYING ACCOUNTS
              For the Years Ended December 31, 1998, 1999 and 2000
                                 (In thousands)

<TABLE>
<CAPTION>

Col. A                                   Col. B                              Col. C              Col. D            Col. E
------                                  ---------                            ------              ------            ------
                                                                   Additions
                                        Balance at       ------------------------------
                                        Beginning        Charged to        Charged to                            Balance at
                                        of Year            Expense       Other Accounts        Deductions        End of Year
                                        ---------        ----------      -------------         ---------         -----------
<S>                                     <C>              <C>             <C>                   <C>               <C>
Inventory reserve:
   Year ended December 31, 1998           $ 179            $   88            $ --                $  --           $   267
   Year ended December 31, 1999             267               393              --                   --               660
   Year ended December 31, 2000             660               743              --                 (318)            1,085

Allowance for doubtful accounts:
   Year ended December 31, 1998           $  50            $   50            $ --                $  --           $   100
   Year ended December 31, 1999             100               100              --                  (19)              181
   Year ended December 31, 2000             181                22              --                   (3)              200

Warranty reserve:
   Year ended December 31, 1998           $ 300            $  135            $ --                $  --           $  435
   Year ended December 31, 1999             435               165              --                   --              600
   Year ended December 31, 2000             600               588              --                 (143)           1,045

</TABLE>

                                    17

<PAGE>   18

                                  EXHIBIT INDEX
                    (Pursuant to Item 601 of Regulation S-K)
Exhibit
Number                               Description
-------                              -----------

 3.1     Amended and Restated Articles of Incorporation of the Company, as
         amended through May 6, 1998 (conformed copy), filed as Exhibit
         3.1 to the Annual Report of Tollgrade Communications, Inc.
         on Form 10-K for the year ended December 31, 1998 (the
         "1998 Form 10-K").                                                    *

 3.1a    Statement with Respect to Shares dated July 23, 1996 (conformed
         copy), filed as Exhibit 3.1a to the 1998 Form 10-K.                   *

 3.2     Amended and Restated Bylaws of the Company, filed as Exhibit 3.2
         to the Report on Form 10-Q of the Company filed on August 10,
         1999 and incorporated herein by reference thereto.                    *

 4.1     Rights Agreement dated as of July 23, 1996 between the Company
         and Chase Mellon Shareholder Services, L.L.C., filed as Exhibit 1
         to the Company's Registration Statement on Form 8-A and
         incorporated herein by reference thereto.                             *

10.1     Common Stock Purchase Agreement dated November 7, 1994, between
         the Company and the investors listed on Schedule A thereto
         (attachments and exhibits omitted), filed as Exhibit 10.1 to the
         Company's Registration Statement on Form S-1 (the "S-1") and
         incorporated herein by reference thereto.                             *

10.2     1995 Long-Term Incentive Compensation Plan, amended and restated
         as of January 5, 2001, filed as Exhibit B to the Company's 2001
         Proxy Statement and incorporated herein by reference thereto.         *

10.3     License Agreement, dated August 24, 1993 between Fujitsu Network
         Transmission Systems, Inc. and the Company, filed as Exhibit 10.4
         to the S-1 and incorporated herein by reference thereto.              *

10.4     License Agreement, dated September 26, 1994 between NEC America,
         Inc. and the Company, filed as Exhibit 10.5 to the S-1 and
         incorporated herein by reference thereto.                             *


                                    18
<PAGE>   19

10.5     Interface License Agreement, dated March 22, 1995 between
         Northern Telecom Inc. and the Company, filed as Exhibit 10.7 to
         the S-1 and incorporated herein by reference thereto.                 *

10.6     Technical Information Agreement, dated February 1, 1993 between
         American Telephone and Telegraph Company and the Company, filed
         as Exhibit 10.8 to the S-1 and incorporated herein by reference
         thereto.                                                              *

10.7     Technology License Agreement, dated November 16, 1994 between DSC
         Technologies Corporation and the Company, filed as Exhibit 10.12
         to the S-1 and incorporated herein by reference thereto.              *

10.8     License Agreement, dated August 24, 1993 between Reliance
         Comm/Tec Corporation and the Company, filed as Exhibit 10.13 to
         the S-1 and incorporated herein by reference thereto.                 *

10.9     Employment Agreement, dated as of December 13, 1995, between the
         Company and Christian L. Allison, filed as Exhibit 10.11 to the
         Annual Report of the Company on Form 10-K for the year ended
         December 31, 1995 (the "1995 Form 10-K").                             *

10.10    Stock Option Agreement entered into December 14, 1995 between the
         Company and R. Craig Allison, together with a schedule listing
         substantially identical agreements with Gordon P. Anderson,
         Jeffrey Blake, John H. Guelcher, Richard H. Heibel, Joseph T.
         Messina and Douglas T. Halliday, filed as Exhibit 10.14 to the
         1995 Form 10-K.                                                       *

10.11    Form of Stock Option Agreement dated December 14, 1995 and
         December 29, 1995 for Non-Statutory Stock Options granted under
         the 1995 Long-Term Incentive Compensation Plan, filed as Exhibit
         10.15 to the Annual Report of the Company on Form 10-K for the
         year ended December 31, 1996 (the "1996 Form 10-K").                  *

10.12    Form of Stock Option Agreement for Non-Statutory Stock Options
         granted under the 1995 Long Term Incentive Compensation Plan,
         filed as Exhibit 10.2 to the Report On Form 10-Q of the Company
         filed on November 12, 1996.                                           *

10.13    Form of Non-employee Stock Option Agreement entered into December
         13, 1996 and December 30, 1997 between the Company and Lawrence
         Arduini, filed as Exhibit 10.19 to the 1996 Form 10-K.                *


                                    19
<PAGE>   20

10.14    Amendment to Employment Agreement, dated as of December 13, 1996,
         between the Company and Christian L. Allison, filed as Exhibit
         10.20 of the 1996 Form 10-K.                                          *

10.15    Amendment to Employment Agreement, dated as of December 13, 1997,
         between the Company and Christian L. Allison, filed as Exhibit
         10.21 to the Annual Report of the Company on Form 10-K for the
         year ended December 31, 1997 (the "1997 Form 10-K").                  *

10.16    Amendment, dated February 21, 1997, to Technical Information
         Agreement relating to Metallic Channel Units Types A and B, dated
         February 1, 1993, between American Telephone and Telegraph
         Company (AT&T) (licensor) and the Company (licensee) incorporated
         by reference to Exhibit 10.3 to the Report on Form 10-Q of the
         Company filed on November 10, 1997.                                   *

10.17    Form of Non-employee Director Stock Option Agreement with respect
         to the Company's 1995 Long-Term Incentive Compensation Plan,
         filed as Exhibit 10.25 to the 1997 Form 10-K.                         *

10.18    Amendment to Employment Agreement, dated as of December 30, 1998,
         between the Company and Christian L. Allison, filed as Exhibit
         10.28 to the 1998 Form 10-K.                                          *

10.19    Amendment to Employment Agreement, dated as of January 18, 2000,
         between the Company and Christian L. Allison, filed as Exhibit
         10.25 to the 1999 Form 10-K.                                          *

10.20    Change in Control Agreement, entered into February 9, 2000
         between the Company and Sara M. Antol, together with a schedule
         listing substantially identical agreements with Robert Cornelia,
         Ruth Dilts, Bradley Dinger, Rocco Flamino, Mark Frey, Samuel
         Knoch, James Price and Matthew Rosgone, filed as Exhibit 10.26 to
         the 1999 Form 10-K.                                                   *

10.21    Change in Control Agreement, entered into December 20, 1999
         between the Company and Scott Robbins, filed as Exhibit 10.27 to
         the 1999 Form 10-K.                                                   *

10.22    Change in Control Agreement, entered into August 10, 2000 between
         the Company and Stephen M. Garda, filed as Exhibit 10.30 to the
         Report on Form 10-Q of the Company filed on November 13, 2000.        *

10.23    Amendment to Employment Agreement, dated as of January 3, 2001,
         between the Company and Christian L. Allison, filed herewith.

10.24    Change in Control Agreement, entered into January 19, 2001
         between the Company and Joseph G. O'Brien, together with a
         schedule listing substantially identical agreements with Lawrence
         J. Fey, William J. Gumbert, Gary L. Gump, Michael D. McSparrin,
         Timothy D. O'Brien, Mark B. Peterson, Roger A. Smith and Jeffrey
         J. Tatusko, filed herewith.                                           *


                                    20
<PAGE>   21

10.25    1998 Employee Incentive Compensation Plan, amended and restated
         as of December 14, 2000, filed herewith.

13.1     Company's 2000 Annual Report to Shareholders, filed herewith.

21.1     List of subsidiaries of the Company, filed as Exhibit 21.1 to the
         S-1 and incorporated herein by reference thereto.                     *

23.1     Consent of PricewaterhouseCoopers LLP, filed herewith.

27       Financial Data Schedule

----------------
 * Incorporated by reference.

                                    21