Foreign exchange service (telecommunications)

Foreign eXchange Station ( FXS) referred to in telecommunications, a device that provides telephone services available in a telephone system connected terminals (FXO devices). As such, it produces, inter alia, the power supply voltage for the terminals, and the ringing signal. Phone jacks are FXS ports. At such a socket connected devices, so for example, telephones or modems, on the other hand have even FXO ports.