AT&T 7200 series, 7500 series, 7100 series, 2500 series, 7400 series, 7300 series manual Ddc, Ddd

GLOSSARY GL-9

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DDC	See Direct Department Calling.
DDD	See direct distance dialing.
dedicated line	Also known as a private or leased line. It is for the exclusive use of the
	leasing party.
dedicated switched	A feature that functions as a hardwired link between two ports on a
connection (DSC)	System 85 (R2V4) or Generic 2 communications system, providing a full-
	time line between the assigned endpoints. Once administered, the
	connection remains intact until removed. Also called nailed-up
	connection. See also permanent switched connection.
default dialing	A terminal dialing feature that automatically originates a call to a
	preassigned number if the user enters a carriage return without first
	entering an address in response to a dial prompt.
demultiplexer	A device used to separate two or more signals that were previously
	combined by a compatible multiplexer and transmitted over a single
	channel.
dial access code (DAC)	A dial code assigned to a feature for activation of the feature from the
	communications-system station set. See also feature-access code and
	trunk-access code.
dialed number	A display provided to the answering agent of a service or project, or of the
identification service	number called by the caller, so that agents grouped in one split can answer
(DNIS)	calls appropriately for different services. DNIS can also be sent to a host
	computer or other adjunct.
digital	The representation of information in discrete elements such as off and on
	or 0 and 1.
digital communications	An AT&T proprietary protocol used to transmit both digitized voice and
protocol (DCP)	digitized data over the same communications link. A DCP link is made up
	of two information (I-) channels and one signaling (S-) channel.
digital data	Data represented in discrete, discontinuous form, usually binary. This is
	in contrast to continuous analog data, usually represented in sine wave
	form.
digital facility	A switching or transmission facility specifically designed to handle digital
	signals.