Foreign exchange service
In
telecommunication, a
foreign exchange service (FX) is a
network-provided service in which a
telephone in a given local exchange area is connected, via a
private line, to a
central office in another,
i.e., "foreign", exchange, rather than the local exchange area's central office.
Note: To call originators, it appears that the subscriber having the FX service is located in the foreign exchange area.
Source: from Federal Standard 1037C