About: PSTN network topology

PSTN network topology is the switching network topology of a telephone network connected to the public switched telephone network (PSTN). In the United States and Canada, the Bell System network topology was the switching system hierarchy implemented and operated from c. 1930 to the 1980s for the purpose of integrating the diverse array of local telephone companies and telephone numbering plans to achieve nationwide Direct Distance Dialing (DDD) by telephone subscribers. It was the precursor of the world-wide interconnected public switched telephone network (PSTN) and originated in the efforts of the General Toll Switching Plan that by 1929 formulated the technical infrastructure and the operating principles for connecting long-distance telephone calls in North America.