1 EXHIBIT 15 May 11, 2000 Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 RE: Tollgrade Communications, Inc. and subsidiaries 1). Form S-8 (Registration No. 333-4290) 1995 Long-Term Incentive Compensation Plan and Individual Stock Options Granted to Certain Directors and Employees Prior to the Adoption of the Plan 2). Form S-8 (Registration No. 333-52907) 1998 Employee Incentive Compensation Plan Ladies and gentlemen: We are aware that our report dated April 12, 2000 on our review of interim financial information of Tollgrade Communications, Inc. and subsidiaries as of and for the three month period ended April 1, 2000 and in the Company's quarterly report on Form 10-Q for the quarter then ended is incorporated by reference in the registration statements referred to above. Very truly yours, /s/ PricewaterhouseCoopers LLP