Early telephone networks were the result of years of evolution, with little thought about future technology. Based around analog equipment, the telephone network of the early telephone company was not well suited for services such as data and video. Many individual technology service providers began popping up during the 1960s, providing packet-switching network and data communications services the telephone companies were just not equipped to provide.

The international telephone network was facing the same problems. In many countries, just getting telephone service was a feat in itself. As international bodies began investigating alternative technologies for providing telephone service to the masses (such as cellular), the need for an all-digital network became apparent. Thus arose the beginnings of an all-digital network with the intelligence.

The International Telecommunications Union (ITU) commissioned the then CCITT to study the possibility of an all-digital intelligent network. The result was a series of standards known now as Signaling System #7 (SS7). These standards have paved the way for the Intelligent Network (IN) and, with it, a variety of services, many yet to be unveiled.

Copied with permission,McGraw-Hill Telecommunications from the book Signaling System #7, Second Edition by Travis Russell, 1998 McGraw-Hill Telecommunications, page 1.