This Recommendation provides guidance, principles and requirements for addressing reference
points located at subscribers' premises, servers allowing communications between terminals,
applications and persons in B-ISDN networks.
1996ITU-T E.191-1996 B-ISDN Numbering and Addressing - Series E: Telephone Network and ISDN Operation, Numbering, Routing and Mobile Services - International Operation - Tones in National Signalling Systems Study Group 2; 17 pp