Common Channel Interoffice Signaling: History and Description of a New Signaling System
C. A. Dahlbom, Juliette Ryan · Bell System Technical Journal · 1978
A new interoffice signaling system known as the Common Channel Interoffice Signaling System (CCIS) has been introduced into the Bell System's DDD toll network. It represents a major step forward in signaling systems by providing high speed data links between processors of stored-program-controlled switching offices to carry all signaling and network control information, completely independent of the communication paths used by customers. As CCIS implementation proceeds it will have an expanding and significant impact on the DDD network system performance due to improved speed of signaling and provision of signals to provide a multitude of new network and customer services. The history of common channel signaling is traced from early mechanical implementation to use of present-day technological advances. The fundamental concepts, basic features, signal formats and system operation are described.