AT&T 2500 series Network Router User Manual


 
GLOSSARY GL-13
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final trunk group A last-choice trunk group that receives overflow traffic and may receive
first-route traffic. See also trunk group.
first-choice trunk group The group of trunks on a communications system that is chosen first for a
particular call. See also trunk group.
flexible assignment of
BX.25 (DCIU/PI)
signaling ports
A feature that allows ports normally reserved for an application to be used
for another application. In the initial implementation of data
communications interface unit and the switch communications/processor
interface (DCIU-SCI/PI) signaling ports in System 75, System 85 and
Generic 1 and 2, certain such ports were reserved for specific applications.
See also BX.25.
foreign exchange (FX) See FX.
frame One of several segments of an analog or digital signal that has a repetitive
characteristic. For example, in a time division multiplexed (TDM) system,
a frame is a sequence of time slots, each containing a sample from one of
the channels served by the multiplex system. The frame is repeated at the
sampling rate, and each channel occupies the same sequence position in
successive frames. See also D4 framing format and extended
superframe framing format.
front end processor (FEP) A communications front end processor interfaces a host to a
telecommunications network. FEP can perform any of the following
functions: code translation, polling, addressing, dial-up, protocol
enveloping and conversion, header analysis, text editing and message
queuing.
full-duplex transmission A transmission system capable of carrying signals in both directions
simultaneously.
FX (foreign exchange) A central office (CO) other than the one providing local access to the
public network.
FX trunk A telecommunications facility that connects a communications system to a
central office (CO) other than its own.
general-purpose port
(GPP)
On the System 85 and Generic 2, a port used for either a digital telephone
or a data module. The GPP uses the digital communications protocol
(DCP) and can be used as an appearance for either a line or a trunk.
generalized route
selection (GRS)
An enhancement to Automatic Alternate Routing/Automatic Route
Selection (AAR/ARS) that performs routing based on call attributes, such
as bearer capability classes (BCS), in addition to the address and facilities
restriction level (FRL).
glare The simultaneous seizure of a two-way trunk by two communications
systems, resulting in a standoff.