Foreign exchange station
From Wikipedia, the free encyclopedia
A Foreign Exchange Station, or FXS, is a telephone interface that receives POTS, or Plain old telephone service. It generates the on-hook and off-hook indicators used to signal a loop closure at the FXO's end of the circuit. Analog telephone handsets, fax machines and (analogue) modems are FXS devices. FXS interfaces are also available for computers and networking equipment to allow these to interact directly with POTS systems. These are commonly found in devices acting as gateways between VoIP systems and the PSTN.
[edit] In a nutshell
FXS is any device that, from the point of view of a telephone exchange, seems to be a regular telephone. As such, it should be able to accept ring signals, go on-hook and off-hook, and send and receive voice signals.
