Common channel signaling network evolution

This paper traces the evolution of the AT&T common channel signaling (CCS) network from its initial deployment as the common channel interoffice signaling (CCIS) network in 1976 to its present and future forms. Since the introduction of CCIS, the network has: added datagram direct-signaling capability, been reconfigured as a result of the AT&T divestiture, and been modernized by new digital and processor technology and by developments in software engineering techniques. In addition, the CCS network has become a key part of the AT&T service architecture, allowing faster nationwide deployment of services. The globalization and further functional enhancements of the network are also discussed.