Glossary-11
dialup line, dial line
A circuit or connection on the public telephone network.
DID, direct inward dialing
A service offered by the telephone company allowing an outside caller to dial
an internal extension without passing through the operator. Billing does not
start until the extension answers.
digital loopback
A diagnostic test that forms the loop at the communication device's data
terminal equipment (DTE) interface.
DISA, direct inward system access
A service offered by a PBX that allows incoming calls to the PBX to have
dialing access within the private network. It may often be protected by a
dialed password. Billing starts when the PBX provides the dial tone.
discard eligibility
See
DE
disconnect supervision
A voice feature which indicates to the local user that the remote end has gone
offhook. This feature is significant in loop start application, where
disconnect is denoted by removal of power to the station equipment.
DIT, direct in termination
A service offered by a PBX that allows incoming calls to the PBX to be routed
directly to a selected telephone or group of telephones without operator
intervention. Billing does not start until the telephone answers.
DLC, data link connection
The frame relay data stream.
DLC, data link control
A bit oriented communications protocol that sets up, controls, checks, and
terminates information transfer between two stations on a data link.
DLCI, data link connection identifier
1) To identify the different DLCs in a frame relay link, each DLC is assigned
a data link connection identifier (DLCI) when a frame relay call is being
established. 2) A unique number assigned to a permanent virtual circuit
(PVC) endpoint in a frame relay network. Identifies a particular PVC
endpoint within a frame relay link in a network; it has local significance only
to that link. During the data transfer phase, all the frames belonging to a
frame relay call carry the same DLCI in the link layer address field of each
frame.
