Avaya Communication Manager Administrator's Manual page 1793

D-channel backup
Type of backup used with Non-Facility Associated Signaling (NFAS). A primary D-channel provides
signaling for an NFAS D-channel group (two or more PRI facilities). A second D-channel, on a
separate PRI facility of the NFAS D-channel group, is designated as backup for the D-channel.
Failure of the primary D-channel causes automatic transfer of call-control signaling to the backup
D-channel. The backup becomes the primary D-channel. When the failed channel returns to service, it
becomes the backup D-channel.
DCO
Digital central office
DCP
Digital Communications Protocol
DCS
Distributed Communications System
DDC
Direct Department Calling
DDD
Direct Distance Dialing
delay-dial trunk
A trunk that allows dialing directly into a communications system (digits are received as they are
dialed).
denying a request
Sending a negative acknowledgment (NAK), done by sending an FIE with a return error component
(and a cause value). It should not be confused with the denial event report that applies to calls.
designated voice terminal
The specific voice terminal to which calls, originally directed to a certain extension, are redirected.
Commonly used to mean the forwarded-to terminal when Call Forwarding All Calls is active.
dial-repeating trunks
A PBX tie trunk that is capable of handling PBX station-signaling information without attendant
assistance.
dial-repeating tie trunk
A tie trunk that transmits called-party addressing information between two communications systems.
DID
Direct Inward Dialing
digit conversion
A process used to convert specific dialed numbers into other dialed numbers.
digital
The representation of information by discrete steps. See also analog.
Administrator's Guide for Avaya Communication Manager
November 2003
Glossary and Abbreviations
1793
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