Voice over IP Fundamentals, Second Edition

Chapter 4. Signaling System 7

Signaling System 7 (SS7) is a common-channel signaling standard developed in the late 1970s by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T), formerly known as the Consultative Committee for International Telegraph and Telephone (CCITT). SS7 was derived from SS6, which was developed in the late 1960s and was the first generation of common-channel signaling. SS7 was initially designed for telephony call-control applications. SS7 applications have greatly expanded since they were first developed, however, and today’s SS7 functionality includes database queries, transactions, network operations, and Integrated Services Digital Network (ISDN).

The SS7 network provides the intelligence ...