Communications System Owner Manual

GLOSSARY GL-23
_ ______________________________________________________________________________________
_ ______________________________________________________________________________________
_ ______________________________________________________________________________________
tip and ring Tip and ring are common nomenclature derived from old cord switchboard
technology to differentiate between the two leads of an analog line or
trunk.
trunk A dedicated telecommunications channel between two communications
systems or central offices (COs). See also facility.
trunk data module
(TDM)
A device that provides the interface for connection between off-premises
private-line trunk facilities and a communications system. The TDM
provides conversion between the RS-232C and the digital communications
protocol (DCP), and can connect to direct distance dialing (DDD) modems
as the DCP member of a modem pool.
trunk group Trunks that can be used interchangeably between two communications
systems or central offices (COs). See also final trunk group and first-
choice trunk group.
trunk port The data- or voice-transmission access point on a device that is used for
each circuit associated with a trunk group.
twisted pair Two copper wires used for the transmission of voice and/or data.
Uniform Call Distribution
(UCD)
A Call Management System (CMS) feature that provides automatic
connection of incoming calls to agents who have been administered in
hunt groups called splits. See also Automatic Call Distribution, Direct
Department Calling, and Enhanced Uniform Call Distribution.
Uniform Dial Plan (UDP)
function
A feature that allows a unique number assignment (4- or 5-digit) for each
terminal in a multicommunications-system configuration such as an ETN
or main-satellite-tributary configuration.
uniform numbering plan
(UNP)
A 4-, 5-, 6-, or 7-digit private-network numbering plan that provides a
unique address for every station and/or terminal on the network.
unrestricted [channels] Unrestricted channels have no restrictions on the number of consecutive
zeros of user data that can be transmitted. The line equipment transmitters
on restricted channels use B8ZS line coding.
virtual circuit The entire path between two end processors. A virtual circuit can consist
of more than one communications link and is also used in packet
switching. In the data communications interface unit (DCIU) application,
the terms control path or data path are used instead of virtual circuit.
voice-grade trunk A channel that carries voice calls and analog voice-band data calls.
voice terminal A single-appearance or multiappearance telephone.