public switched telephone network (PSTN)

The public switched telephone network (PSTN) is the network of the world's public circuit-switched telephone networks, in much the same way that the Internet is the network of the world's public IP-based packet-switched networks. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital, and now includes mobile as well as fixed telephones. There are many advantages for PSTN as a communications link:

• Other than a modem, no additional equipment is required.


• The cost associated with the implementation of a PSTN connection link for a WAN is relatively low.


• The maintenance of a public telephone network is very high quality with few instances in which lines are not available.