D

D channel

A data channel of the ISDN interface. It is one of the three standard channels on a Basic Rate ISDN line. On a BRI-ISDN line, a D channel can carry signaling information and low-speed packet data at a rate of 16,000 bps. On a PRI-ISDN line, the D channel runs at 64,000 bps. See also Basic Rate Interface (BRI-ISDN), B channel, Primary Rate Interface (PRI-ISDN).

device class

A group of related physical devices or device drivers through which applications send and receive the information or data that makes up a call. For a list, see TAPI Device classes.

DID

See direct inward dialing (DID).

direct inward dialing (DID)

An ability provided by virtually all modern PBXs that allows an external caller to reach an internal extension by dialing a standard seven-digit telephone number without having to pass through an operator or attendant. See also private branch exchange (PBX).

DLL

See dynamic-link library (DLL).

dynamic-link library (DLL)

A feature that allows executable code modules to be loaded on demand and linked at run time. This enables the library-code fields to be updated automatically, transparent to applications, and then unloaded when they are no longer needed.