The telephone network is generally understood to mean the analog telephone network with its nationwide, wireline infrastructure. These service-neutral communication paths are used for voice and data communication. Thus for analog or digital telephony( ISDN), for the former Datex services and leased lines.
The network structure of the public telephone network consists of the switching equipment such as the central exchange, node exchange, long-distance exchange and local exchange, and the access network.
Characteristic of the telephone network is connection-oriented transmission with circuit switching. Communication takes place via explicitly established transmission paths between subscriber interfaces. These dial-up connection paths are set up temporarily and remain in place for the duration of the telephone call. Afterwards, they are removed again.
The analog telephone network POTS (Plain Old Telephone Service) and also ISDN use the same switching and transmission facilities in the public network.