This product turns ordinary electrical sockets into telephone outlets. It is suitable for use with a PC set top box telephone or fax. No extra wiring is required & it is completely portable & compatible with PC modems. Simply plug in the base unit near to the master telephone socket a through connector allows connection to the master socket without interrupting the existing phone. The extension unit can then be plugged in anywhere in any room where a mains socket is located to give you an additional telephone socket without having to run unsightly cable.