This paper describes the evolution and architecture of the Stored Program Controlled (spc) Network. The critical role of common‐channel interoffice signaling (ccis) is discussed, both as an improved method for providing the traditional signaling functions, and as the key to a wide range of new service opportunities. These are made possible by the ability to interrupt call progress and, in real‐time, interrogate a distant data base and modify the subsequent call handling based on the information returned. The underlying architecture by which these services are implemented is based on the objectives of providing ubiquitous service with limited deployment of essential network capabilities and creating a structure which permits customized services by modifying the contents of a centralized data base.

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