ISDN User Part

ISUP
The ISDN (Integrated Services Digital Network) User Part or ISUP is part of Signaling System No. 7 (SS7), which is used to set up telephone calls in the public switched telephone network (PSTN).wikipedia
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Telephone call

callphone callphone calls
The ISDN (Integrated Services Digital Network) User Part or ISUP is part of Signaling System No. 7 (SS7), which is used to set up telephone calls in the public switched telephone network (PSTN).
Most telephone calls through the PSTN are set up using ISUP signalling messages or one of its variants between telephone exchanges to establish the end to end connection.

Signalling System No. 7

SS7SS7 NetworkCCS7
The ISDN (Integrated Services Digital Network) User Part or ISUP is part of Signaling System No. 7 (SS7), which is used to set up telephone calls in the public switched telephone network (PSTN).
The Telephone User Part (TUP) was adopted in Europe and the Integrated Services Digital Network (ISDN) User Part (ISUP) adapted for public switched telephone network (PSTN) calls was adopted in North America.

Public switched telephone network

PSTNtelephone networkpublic telephone network
The ISDN (Integrated Services Digital Network) User Part or ISUP is part of Signaling System No. 7 (SS7), which is used to set up telephone calls in the public switched telephone network (PSTN).
The call is switched using a call set up protocol (usually ISUP) between the telephone exchanges under an overall routing strategy.

Message Transfer Part

MTPMTP 2MTP layer 3
ISUP messages can be sent using the services of the Message Transfer Part, or, less often, the Signalling Connection Control Part. The Routing Label indicates the Point Codes of the originating and destination nodes in the network; it also includes the Signalling Link Selection field that is used to select between the multiple routes an MSU could take between two nodes.
Some examples of parts at Level 4 are SCCP, ISUP, TUP, and, in the UK, IUP.

Integrated Services Digital Network

ISDN ISDNISDN30
Integrated Services Digital Network (ISDN)
ISDN User Part (ISUP)

ITU-T

CCITTTelecommunication Standardization SectorComité Consultatif International Téléphonique et Télégraphique
It is specified by the ITU-T as part of the Q.76x series.

Telephone exchange

exchangescentral officeexchange
When a telephone call is set up from one subscriber to another, several telephone exchanges could be involved, possibly across international boundaries. To allow a call to be set up correctly, where ISUP is supported, a switch will signal call-related information like called party number to the next switch in the network using ISUP messages. The telephone exchanges may be connected via E1 or T1 trunks which transport the speech from the calls.

Called party

calleebe calledcall receiver
To allow a call to be set up correctly, where ISUP is supported, a switch will signal call-related information like called party number to the next switch in the network using ISUP messages.

E-carrier

E1E-1digital trunks
The telephone exchanges may be connected via E1 or T1 trunks which transport the speech from the calls.

T-carrier

T1T-1T1 carrier
The telephone exchanges may be connected via E1 or T1 trunks which transport the speech from the calls.

Circuit identification code

(CIC)
Regardless of what facilities are used to interconnect switches, each circuit between two switches is uniquely identified by a circuit identification code (CIC) that is included in the ISUP messages.

ETSI

European Telecommunications Standards InstituteEuropean Telecommunications Standards Institute (ETSI)ETS
In Europe ETSI releases its own ISUP specification which is close that of the ITU-T.

American National Standards Institute

ANSIASAAmerican National Standard
ANSI specifies variations of ISUP utilized under the North American Numbering Plan; however, some countries under the NANP differ in their support of some procedures (for example, LATA is meaningless within Canada.

North American Numbering Plan

Area codeArea codesArea code(s)
ANSI specifies variations of ISUP utilized under the North American Numbering Plan; however, some countries under the NANP differ in their support of some procedures (for example, LATA is meaningless within Canada.

Local access and transport area

LATALATA codeLATAs
ANSI specifies variations of ISUP utilized under the North American Numbering Plan; however, some countries under the NANP differ in their support of some procedures (for example, LATA is meaningless within Canada.

Regional Bell Operating Company

Regional Bell Operating CompaniesBaby BellsBaby Bell
Also, RBOCs support Telcordia procedures not fully specified by ANSI.) Some countries outside the NANP support ANSI-based variants (e.g. Mexico).

Telcordia Technologies

BellcoreiconectivTelcordia
Also, RBOCs support Telcordia procedures not fully specified by ANSI.) Some countries outside the NANP support ANSI-based variants (e.g. Mexico).

Signalling Connection Control Part

SCCPNSP
ISUP messages can be sent using the services of the Message Transfer Part, or, less often, the Signalling Connection Control Part.

Quality of service

QoSquality-of-serviceQuality of Service (QOS)
1) Quality of service unavailable

Point code

Signaling Point Code
The Routing Label indicates the Point Codes of the originating and destination nodes in the network; it also includes the Signalling Link Selection field that is used to select between the multiple routes an MSU could take between two nodes.

Release

released
Release (ISUP), a code to identify and debug events in ISUP signaling

Trio AB

While Trio was built during SS7/ISUP, it has been adapting to use VoIP in its newer products.