D channel (delta channel) is a

telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

term which refers to the

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...

channel in which the control and

signal In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...

ling information is carried. The bit rate of the D channel of a

basic rate interface Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic Rate Access is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone servi ...

is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface. For

DSS1 Digital Subscriber Signalling System No. 1 (DSS1) is a digital signalling protocol (D channel protocol) used for the ISDN. It is defined by ITU-T I.411 (ETS 300 102). It supports Bearer Capability, Low Level Compatibility and High Level Compat ...

signalling, the D channel layer 2 protocol is Q.921 also called LAPD and it carries Layer 3 messages according to

Q.931 ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of ''Digital Subscriber Signalling System No. 1''. Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit sign ...

protocol.

See also