B-22
Appendix B: Glossary
FTTC Fiber-To-The-Curb. Refers to the installation of fiber optic cable directly to the
curbs near homes or businesses. Fiber optic cable, which provides much
greater transmission speeds than copper wiring, is already used for much of
the POTS long-distance infrastructure. By decreasing the time it takes data to
travel from a customer to the customer’s provider, FTTC would greatly
increase individual users’ data-transmission speeds.
FTTH Fiber-To-The-Home. Refers to the installation of high-speed fiber optic cable,
rather than copper cable, directly to the home.
FX Foreign eXchange. A telephone service, using VoIP technology, that allows a
user to have a number with an exchange that is not the normal exchange for
the user’s geographic area.
FXO Foreign Exchange Office. A VoIP telephone interface, usually a standard
analog telephone, that receives calls over POTS. The FX0 generates the on-
hook and off-hook indicators used to signal a loop closure at the FXO’s end
of the circuit. The FXO must be connected to the FSX interface.
FXS Foreign Exchange Station. A VoIP telephone device that provides battery
power, sends the dial tone, and generates ringing voltage for the FXO. The
FXO plugs directly into the FXS to provide telephone service for the VoIP
device.
F5 OAM F5 Operation And Maintenance. ATM devices send OAM cells over an ATM
link to monitor the link. F5 OAM cells verify that an ATM link is open from
end-to-end.
G
GRE Generic Routing Encapsulation. A Layer 2 protocol that can encapsulate many
types of OSI Layer 2 or Layer 3 protocols and place them in IP packets. Routers
can use GRE to tunnel packets, such as multicast packets, that could other-
wise be sent over the Internet. Routers can also use GRE to create virtual
point-to-point links through an IP network. For more information on GRE, see
RFC 2784 (at http://www.ietf.org/rfc/rfc2784.txt).
GS Ground Start. A method by which a device signals a switch to start a call. An
on-hook condition begins as a completed circuit. An off-hook condition opens
a circuit by grounding a 2600-Hz tone, informing the switch to provide dial
tone. See also LS.
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