Push-to-talk PSTN back-to-back user agent for connecting a PTT system to the PSTN/ISDN world

A method for carrying out a Push-to-Talk communication in a digital and/or analog telephone network, including an interface for a semi-duplex communication between a Push-to-Talk server and the analog or digital telephone network and the analog or digital network. The interface uses a communication node or group system as computer and carries out a communication in a transmission channel with automatic directional switching in an analog or digital telephone network in the direction of an available Push-to-Talk server, the analog or digital telephone network being designed as an audio and control interface in the direction of the operating means.