Glossary - D

DAT

Digital Audio Tape.

DDI

Direct Dialling In.

DDS

Digital Data Service.

Direct Mail

Printed matter, usually carrying a sales message or announcement, designed to elicit a response from a carefully selected consumer or business market.

DLT

Digital Linear Tape.

DNIS

Dialled Number Identification System. A telephony switching feature that enables identification of the called number (B Party) and allows user-defined actions to be performed based on its value.

DPNSS

Digital Private Network Signalling System.

DRAN

Digital Recorded Announcement. A DRAN may originate in the PSTN or from the ACD. The origin is generally be transparent to the callers.

DRP

Disaster Recovery Procedure / Plan.

DSVD

Digital Simultaneous Voice and Data. The simultaneous transmission of voice and data over a digital telephone line (see also AVD, SVD and VDCA).

DTMF

Dual Tone Multi-Frequency. Each numeral is transmitted as a pair of concurrent audio frequencies. In addition to being used to establish connections, DTMF signalling may be used to exercise control during a call, e.g. in conjunction with an IVR device.