Glossary and Abbreviations
D
Administrator’s Guide for Avaya Communication Manager
1793
November 2003
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
.