Common channel signalling for international services

This paper describes work done by AT&T, KDD and BTI to define an international common channel signalling specification based on CCITT No. 7 for use in supporting international services. This work began in 1986 with the goal of reaching agreement on a signalling protocol specification that would be the basis for supporting new and improved international services. As a result of this work, a specification for Integrated Services Digital Network User Part (ISUP) has been written to initially provide a frame work for operations among the three companies, and, later, potentially worldwide.