EXHIBIT 10.17 CAIS, INC. 1232 22nd Street, N.W. Washington, D.C. 20037 Tel. (202) 463-8500 Fax (202) 463-7190 October 21, 1997 Mr. David D. Goodman Inline Connection Corporation 730 N. Danville Street Arlington, VA 22201 Dear David: This will confirm our agreement regarding certain modifications to the November 5, 1996 Agreement for Cooperative Use of Communication Patents among Inline Connection Corporation, you in your individual capacity, and CAIS, Inc. (the "Agreement"). For good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the second sentence of the sixth paragraph of Section 4 of the Agreement is hereby revised to provide as follows: "CAIS hereby agrees to commit to spend up to $200,000 from the date of this Agreement through a date nine (9) months following the date of the exercise of the Option." All other terms and conditions of the Agreement remain in full force and effect. If the above reflects your understanding and meets with your approval, please so indicate by countersigning below on behalf, respectively, of Inline and in your individual capacity. Sincerely, CAIS, Inc. By: /s/ Ulysses G. Auger, II ---------------------------------------- Ulysses G. Auger, II, President Agreed to: Inline Connection Corporation By: /s/ David D. Goodman -------------------------------- David D. Goodman, President 10/21/97 ----------------------- Date Agreed to: /s/ David D. Goodman --------------------------------- David D. Goodman, in his individual capacity 10/21/97 ---------------------- Date