AT&T 7400 series, 7500 series, 7100 series, 2500 series, 7200 series manual See digital telephone

GL-10GLOSSARY

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digital multiplexed interface (DMI)

digital multiplexed interface with bit-oriented signaling (DMI-BOS)

digital multiplexed interface with message- oriented signaling (DMI- MOS)

digital signal level 1 (DS1)

digital transmission

digital-terminal data module (DTDM)

digital telephone

digital voice terminal

direct distance dialing (DDD)

direct inward dialing (DID)

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).

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.

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).

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.

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.

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.

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.

See digital telephone.

The capability of completing long-distance calls without operator assistance.

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.