Common channel interoffice signaling: An overview

In May of 1976, a new Common Channel Interoffice Singnaling (CCIS) system linked together the last new No. 4A toll crossbar office in Madision Wisconsin and the first No. 4 ESS toll office in Chicago, Illinois. This was a major milestone in a long-range program to achieve a nationwide Stored-Program Controlled (SPC) network of stored-program controlled switching offices interconnected by a new high-speed, high-capacity interoffice signaling system, CCIS. The SPC network will provide faster, more reliable communication services. An evolutionary transition to the SPC network is in progress. CCIS is now being implemented in the toll or long-distance network. It will subsequently be extended to Traffic Service Position System (TSPS) units and to Electronic Switching System (ESS) local switching offices to provide customer-to-customer CCIS service.