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                                                                   Exhibit 10.21


                                    AMENDMENT

THIS AMENDMENT, dated as of January 10, 1998 (herein called the "Amendment"), is
entered into by and between TOLLGRADE COMMUNICATIONS, INC. (herein referred to
"Tollgrade") and R. CRAIG. ALLISON (herein referred to as the "Executive").


                             AMENDMENT TO AGREEMENT

WHEREAS, Tollgrade and the Executive entered into an Agreement effective dated
the 13th day of December, 1995 and amended effective January 14, 1997 governing
the employment of the Executive and certain benefits to be received by the
Executive in the event his employment is terminated (herein referred to as the
"Agreement"); and

WHEREAS, Tollgrade and the Executive desire to amend the Agreement upon the
terms and conditions stated in this Amendment.

NOW, THEREFORE, in consideration of the promises and the faithful performance of
the mutual covenants herein contained, and intending to be legally bound hereby,
Tollgrade and the Executive agree as follows:

1.       Capitalized terms used herein and not otherwise defined in this
         Amendment shall have the meaning assigned to them in the Agreement.

2.       The Agreement shall be amended such that the Executive's base salary,
         as specified in Section 2(b) of the Agreement, shall be increased to
         $193,000 per annum, effective as of the anniversary date of the
         Agreement.

3.       Except as modified by this Amendment, the provisions of the Agreement
         will remain in full force and effect.

         IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date first above written.

                                              TOLLGRADE COMMUNICATIONS, INC.

                                              By:       /s/ SARA M. ANTOL
                                                 -------------------------------
                                              Title: Chief Counsel & Secretary
                                                     ---------------------------


                                              /s/ R. CRAIG ALLISON
                                              ----------------------------------
                                              R. Craig Allison


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                                    AMENDMENT

THIS AMENDMENT, dated as of January 8, 1998 (herein called the "Amendment"), is
entered into by and between TOLLGRADE COMMUNICATIONS, INC. (herein referred to
"Tollgrade") and CHRISTIAN L. ALLISON (herein referred to as the "Executive").


                             AMENDMENT TO AGREEMENT

WHEREAS, Tollgrade and the Executive entered into an Agreement effective dated
the 13th day of December, 1995 and amended effective January 14, 1997 governing
the employment of the Executive and certain benefits to be received by the
Executive in the event his employment is terminated (herein referred to as the
"Agreement"); and

WHEREAS, Tollgrade and the Executive desire to amend the Agreement upon the
terms and conditions stated in this Amendment.

NOW, THEREFORE, in consideration of the promises and the faithful performance of
the mutual covenants herein contained, and intending to be legally bound hereby,
Tollgrade and the Executive agree as follows:

1.       Capitalized terms used herein and not otherwise defined in this
         Amendment shall have the meaning assigned to them in the Agreement.

2.       The Agreement shall be amended such that the Executive's base salary,
         as specified in Section 2(b) of the Agreement, shall be increased to
         $193,000 per annum, effective as of the anniversary date of the
         Agreement.

3.       Except as modified by this Amendment, the provisions of the Agreement
         will remain in full force and effect.

         IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date first above written.

                                             TOLLGRADE COMMUNICATIONS, INC.

                                             By:       /s/ SARA M. ANTOL
                                                --------------------------------
                                             Title: Chief Counsel & Secretary
                                                    ----------------------------

                                               /s/ CHRISTIAN L. ALLISON
                                             -----------------------------------
                                             Christian L. Allison


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