Exhibit 4.1 CERTIFICATE AND AMENDMENT TO RIGHTS AGREEMENT CERTIFICATE AND AMENDMENT, dated September 23, 2001 (this "AMENDMENT"), to the Rights Agreement, dated as of November 20, 1998 (the "RIGHTS AGREEMENT"), between Illuminet Holdings, Inc., a...Rights Agreement • November 14th, 2001 • Illuminet Holdings Inc • Telephone communications (no radiotelephone) • Delaware
