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