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GL-10 GLOSSARY
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digital multiplexed
interface (DMI)
An interface that provides connectivity between a communications system
and a host computer or between two communications systems using digital
signal level-1 (DS1) 24th-channel signaling. DMI provides 23 64-kbps
data channels and 1 common signaling channel over a twisted-pair
connection. DMI is offered through two capabilities: bit-oriented
signaling (DMI-BOS) and message-oriented signaling (DMI-MOS).
digital multiplexed
interface with bit-oriented
signaling (DMI-BOS)
DMI signaling in which the signaling in the 24th channel is based on the
definitions of single bits. For example, a bit may indicate an on-hook/off-
hook condition.
digital multiplexed
interface with message-
oriented signaling (DMI-
MOS)
DMI signaling in which the signaling in the 24th channel is based on the
definitions of strings of bits that form messages. DMI-MOS is similar to
the Integrated Services Digital Network primary rate interface (ISDN-
PRI).
digital signal level 1 (DS1) An interface that multiplexes 24 channels into a single 1.544-Mbps
stream. DS1 can be used for pulse-code modulation (PCM) for voice or
voice-grade data and for mode-0, -1, -2, and -3 data protocols as well as
for other voice or data transmission protocols.
digital transmission A mode of transmission in which the information to be transmitted is first
converted to digital form and then transmitted as a serial stream of pulses.
digital-terminal data
module (DTDM)
An integrated or adjunct data module that shares with a digital telephone
the same physical port for connection to a communications system. The
function of a DTDM is similar to that of a processor data module (PDM)
and modular processor data module (MPDM) in that it converts RS-232C
signals to digital communications protocol (DCP) signals.
digital telephone A telephone that converts analog voice signals into digital electrical
signals to be sent along the telephone line. Digital telephones use the
digital communications protocol (DCP) or basic rate interface (BRI), and
are served by two pairs of wire. Digital telephones include the 7400
series, the PT510, and the business communications terminal (BCT). Also
called digital voice terminal and nonanalog telephone.
digital voice terminal See digital telephone.
direct distance dialing
(DDD)
The capability of completing long-distance calls without operator
assistance.
direct inward dialing
(DID)
A feature that allows an incoming call from the public network (not FX or
WATS) to reach a specific telephone without attendant assistance. DID
calls to DID-restricted telephone lines are routed to an attendant or
recorded announcement, depending on the option selected.