Voice-over-Internet Protocol (VoIP) Smart Node solutions .Foreign exchange
Subscriber (FXS) and Foreign exchange Office (FXO).
The question whatis the difference betweenFXS and FXO? is frequently asked by
those deploying Patton Voice-over-InternetProtocol (VoIP) Smart Node solutions.
Foreign exchange Subscriber (FXS) andForeign exchange Office (FXO) are the names
of the two most common interfaces(ports orplugs) found in analog telephony
environments. Analog telephony, alsoknown as Plain Old Telephone Service (POTS),
is the service the local phonecompany typically delivers to your home. Local phone
companies deliver POTSfrom their Central Office (CO) tothe subscriber'spremises
over a circuitconsisting of two copper wires. To increase the distance over which the
signalcan be transmitted the two wires are twisted together, which also reduces
electromagnetic interference. So these two-wire copper cablesare commonlyknown
as twisted pairs.
FXS -Foreign exchange Subscriber interface (the plug on the wall) delivers POTS
service from the local phone companiesCentral Office (CO) and must be connected
to subscriber equipment (telephones,modems,and fax machines). In other words an
FXS interface points to thesubscriber. An FXS interface provides the following
primary services to asubscriber device.
Dial Tone, Battery Current, Ring Voltage
FXO -Foreign exchange Office interface (theplug on the phone) receives POTS
service, typically from a Central Office ofthe Public Switched Telephone Network
(PSTN). In other words an FXO interfacepoints to the Telco office. An FXO interface
provides the following primaryservice to the Telco network device.