Q.931

ITU-T 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.wikipedia
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Integrated Services Digital Network

ISDN ISDNISDN30
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1.
In common use, ISDN is often limited to usage to Q.931 and related protocols, which are a set of signaling protocols establishing and breaking circuit-switched connections, and for advanced calling features for the user.

ITU-T

CCITTTelecommunication Standardization SectorComité Consultatif International Téléphonique et Télégraphique
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1.
ISDN (Integrated Services Digital Network) Q.931

H.323

RAS
Q.931 has more recently been used as part of the VoIP H.323 protocol stack (see H.225.0) and in modified form in some mobile phone transmission systems and in ATM.
H.323 call signaling is based on the ITU-T Recommendation Q.931 protocol and is suited for transmitting calls across networks using a mixture of IP, PSTN, ISDN, and QSIG over ISDN.

Information element

Information elements (IE) – Specify further information which is associated to the actual message. An IE contains the IE name (e.g. bearer capability), their length and a variable field of contents.
An information element, sometimes informally referred to as a field, is an item in Q.931 and Q.2931 messages, IEEE 802.11 management frames, and cellular network messages sent between a base transceiver station and a mobile phone or similar piece of user equipment.

H.225.0

Q.931 has more recently been used as part of the VoIP H.323 protocol stack (see H.225.0) and in modified form in some mobile phone transmission systems and in ATM.
Call Signaling: establish, control and end an H.323 call. The call signaling of H.225.0 is based on the call setup procedures for ISDN, Recommendation Q.931.

Digital Subscriber System No. 1

DSS1Digital Subscriber System No. 1 (DSS1)EDSS1
Protocol discriminator (PD) – Specifies which signaling protocol is used for the connection (e.g. PD=8 for DSS1)
Codeset 0 regards to Q.931, Codeset 5 to the ETSI standard, Codeset 6 for national applications and Codeset 7 for PBX applications.

Signaling (telecommunications)

signalsignalingsignalling
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1.

Communication protocol

protocolprotocolscommunications protocol
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1.

Connectionless communication

connectionlessconnectionless protocolconnectionless mode transmission
Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit signalling to manage call state: Q.931.

User Datagram Protocol

UDPUDP/IPUDP protocol
Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit signalling to manage call state: Q.931.

Connection-oriented communication

connection-orientedconnection orientedconnection-oriented protocol
Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit signalling to manage call state: Q.931.

Session Initiation Protocol

SIPSession Initiation Protocol (SIP)SIP Trunking
Q.931 does not have a direct equivalent in the Internet Protocol stack, but can be compared to SIP.

Flow control (data)

flow controlhardware flow controlCTS
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 fixed increments of 64 kbit/s.

OSI model

OSIOSI Reference Modellayer 2
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 fixed increments of 64 kbit/s.

Circuit switching

circuit switchedcircuit-switchedcircuit mode
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 fixed increments of 64 kbit/s.

Bandwidth (computing)

bandwidthnetwork bandwidthbandwidths
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 fixed increments of 64 kbit/s.

Data-rate units

kbit/sMbit/sbits per second
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 fixed increments of 64 kbit/s.

Transmission Control Protocol

TCPTCP/IPACK
Like TCP, Q.931 documents both the protocol itself and a protocol state machine.

Finite-state machine

finite state machinestate machinefinite automata
Like TCP, Q.931 documents both the protocol itself and a protocol state machine.

Mobile phone

cell phonemobilemobile phones
Q.931 has more recently been used as part of the VoIP H.323 protocol stack (see H.225.0) and in modified form in some mobile phone transmission systems and in ATM.

Broadband Integrated Services Digital Network

B-ISDNBroadband ISDNBroadband ISDNs
Q.2931 is a modified and extended variant of Q.931 for use on "B-ISDN" or ATM networks.

Asynchronous transfer mode

ATMAsynchronous Transfer Mode (ATM)asynchronous
Q.2931 is a modified and extended variant of Q.931 for use on "B-ISDN" or ATM networks.

Traffic management

traffic controltraffic managercontrol
Whilst ISDN allocates bandwidth in fixed 64k increments, B-ISDN/ATM incorporates an elaborate traffic management scheme, allowing precise specification of virtual circuit traffic parameters such as peak and mean bandwidth, jitter, cell loss ratio and so on.

Jitter

wanderphase jitterjitter buffer
Whilst ISDN allocates bandwidth in fixed 64k increments, B-ISDN/ATM incorporates an elaborate traffic management scheme, allowing precise specification of virtual circuit traffic parameters such as peak and mean bandwidth, jitter, cell loss ratio and so on.

Bearer Capability

Bearer Capability is one of the Information Elements (fields) of the Q.931 SETUP message.