AT&T 7300 series, 7500 series, 7100 series, 2500 series, 7200 series, 7400 series manual Ucd, Unp

GLOSSARY GL-23

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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	A device that provides the interface for connection between off-premises
(TDM)	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	A Call Management System (CMS) feature that provides automatic
(UCD)	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)	A feature that allows a unique number assignment (4- or 5-digit) for each
function	terminal in a multicommunications-system configuration such as an ETN
	or main-satellite-tributary configuration.
uniform numbering plan	A 4-, 5-, 6-, or 7-digit private-network numbering plan that provides a
(UNP)	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.