GL-20 GLOSSARY
terminal
balance
Terminating-
Extension
Group (TEG)
time-
multiplexed
switch (TMS)
time-slot
interchanger
(TSI)
TMS
toll office
transport mode
traveling class
mark (TCM)
trunk group
trunk type
TMS
TSI
TTTN
UDP
Uniform Dial
Plan (UDP)
The measured echo-return and singing-return losses for a port when connected to
a specific 2-wire central office (CO) or off-premises network interface. Those
connections that have sufficiently high return loss are assigned reduced tie trunk
connecting losses without impairing talker echo performance or violating stability
criteria.
A feature that provides one-way terminating call service to an extension that can
be shared by a group of analog and/or multifunction (digital or hybrid)
telephones. All members of the group are normally alerted for a new call and
any member can answer. An option for each multifunction-telephone TEG
member provides both unique identification of TEG calls and a means for
bridging onto a TEG call after it has been answered by another member of the
group.
An element of a time-division switching network that effectively operates as a
very-high-speed space-division switch whose input-to-output paths can be
changed to rearrange the interconnection of successive time-slot interchange time
slots. See also time-slot interchanger.
An element of a time-division switching network that separates and switches
time-division-multiplexed signals arriving from multiple calls. See also time-
multiplexed switch.
See time-multiplexed switch.
A class 4, 3, 2, or 1 network switching center. For AT&T, the Toll Office is
almost always a 4 ESS™ switching system.
The bearer-capability information-element (IE) parameter that indicates how the
channel is to be used. Transport mode can be either circuit switched or packet
switched. See also circuit switched transport mode and packet switched
transport mode.
A code used to modify the default facility restriction level (FRL) associated with
a call at the distant communications system when an intertandem tie trunk is
used to route the call. When the TCM is sent on robbed-bit trunks, it is
appended as an additional touch-tone digit that follows the address. When the
TCM is sent over Integrated Services Digital Network (ISDN) trunks, it is
included in one of the Q.931 call-setup messages.
Trunks that can be used interchangeably between two communications systems or
central offices (COs). See also final trunk group and first-choice trunk group.
A generic term or number that defines the trunk signaling and relates that type of
trunk signaling to a particular feature or service.
See time-multiplexed switch.
See time-slot interchanger.
See tandem tie-trunk network.
See Uniform Dial Plan.
A feature that allows a unique number assignment (4- or 5-digit) for each
terminal in a multicommunications-system configuration such as a distributed
communications system (DCS) or main-satellite-tributary configuration.