Integrated Services Digital Network

thumb|ISDN telephone

ISDN configuration

telecommunication standard

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 signalling to manage call state: Q.931. Q.931 typically does not carry user data. Q.931 does not have a direct equivalent in the Internet Protocol stack, but can be compared to SIP. Q.931 does not provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates bandwidth in

Two-binary, one-quaternary (2B1Q) is a line code used in the U interface of the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) and the high-bit-rate digital subscriber line (HDSL). 2B1Q is a four-level pulse-amplitude modulation (PAM-4) scheme without redundancy, mapping two bits (2B) into one quaternary symbol (1Q). Symbol rate is half of data rate.

High-speed Internet access standard

H.320 or Narrow-band visual telephone systems and terminal equipment is an umbrella Recommendation by the ITU-T for running multimedia (audio/video/data) over ISDN based networks. The main protocols in this suite are H.221, H.230, H.242, audio codecs such as G.711 (PCM) and G.728 (CELP), and discrete cosine transform (DCT) video codecs such as H.261 and H.263.

ISDN protocol

Concept in telephony

telephone system protocol used in some parts of the world