The public switched telephone network (PSTN) is the network of the world's civic circuit-switched telephone networks, in much the similar method that the Internet is the network of the world's open IP-based packet-switched networks. Formerly a network of fixed-line analog telephone systems, the PSTN is currently about wholly digital as well as consists of mobile with fixed telephones.

The PSTN is mostly administered by technological standards formed by the ITU-T, as well as make use of E.163/E.164 addresses (more usually renowned as telephone numbers) for addressing.