Public Switched Telephone Network (PSTN)
The 'dedicated circuit' phone network developed by Bell Telephone. This is progressively being superseded by packet switch (data packets) and/or more complex fully digital data streams. But this is where it all started.
from: InetDaemon.Com > definition of PSTN
.. The term PSTN used to refer to the public communication system that provides local, extended local and long distance telephone service to the majority of the United States and North America [and the world]. This system is made available to the public through a group of common communications carriers such as American and Canadian [and other] phone companies who have agreed to exchange calls and connections on behalf of their subscribers as mandated by international law and the laws of the country in which they do business and and provide telephone service. Anyone who subscribes to this public service may make calls to anyone else who has purchased access to the phone system through any other carrier.
The PSTN is composed of telephone exchanges networked together to form a nationwide (and worldwide) telephone communications system. It is public because (theoretically) the system is available to anyone who can afford the service.
[remainder of article mixes 'switched' and 'packet', and is confusing]
