AT&T DS1/DMi/ISDN-PRI manual Terminal balance Terminating Extension Group TEG, Time, Switch TMS

GL-20GLOSSARY

terminal balance

Terminating-

Extension

Group (TEG)

The measured echo-return and singing-return losses for a port when connected to

aspecific 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.

time-	An element of a time-division switching network that effectively operates as a
multiplexed	very-high-speed space-division switch whose input-to-output paths can be
switch (TMS)	changed to rearrange the interconnection of successive time-slot interchange time
	slots. See also time-slot	interchanger.
time-slot	An element of a time-division switching network that separates and switches
interchanger	time-division-multiplexed signals arriving from multiple calls. See also time-
(TSI)	multiplexed switch.
TMS	See time-multiplexed switch.
toll office	A class 4, 3, 2, or 1 network switching center. For AT&T, the Toll Office is
	almost always a 4 ESS™	switching system.

transport mode

traveling class mark (TCM)

trunk group

trunk type

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.

TMS	See time-multiplexed switch.
TSI	See time-slot interchanger.
TTTN	See tandem tie-trunk network.
UDP	See Uniform Dial Plan.
Uniform Dial	A feature that allows a unique number assignment (4- or 5-digit) for each
Plan (UDP)	terminal in a multicommunications-system configuration such as a distributed
	communications system (DCS) or main-satellite-tributary configuration.