Public switched telephone network

The public switched telephone network (PSTN) is the network of the world's public circuit-switchedtelephone networks, in much the same way that the Internet is the network of the world's public IP-basedpacket-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.

The PSTN is largely governed by technical standards created by the ITU-T, and uses E.163/E.164addresses (more commonly known as telephone numbers) for addressing.