Network Interface Device for Telecommunication Terminals

摘要

A telecommunication terminal device is connected to a public telephone network (100) and first and second external connection devices (300,400), one of which is parallel and the other serial. A switching unit (220) selectively connects one of the external terminal devices to the public telephone network (100) by connecting a pin (214) of a PSTN network connection unit (210) associated with the PSTN (100) either to a pin (218) of the PSTN connection unit associated with the first external device connection (210) or to a pin (234) of an external device connection (230) associated with the second external device (400). A second switching unit (260) is arranged to connect a pin (212) of the PSTN connection unit associated with the PSTN (100) either to another pin (214) of the network connection unit associated with the PSTN (100) via a feeding circuit (240), or to a pin (216) of the PSTN connection unit associate with the first external terminal device (300). Automatic switching can occur using input from a terminal detection unit (250).