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The Mobile


Core Network and Terminals

The TSG Core Network and Terminals (TSG CT) is responsible for specifying terminal interfaces (logical and physical), terminal capabilities (such as execution environments) and the Core network part of 3GPP systems.

More specifically: User Equipment - Core network layer 3 radio protocols ( Call Control, Session Management, Mobility Management), signalling between the core network nodes, interconnection with external networks, O&M requirements, GPRS between network entities, Transcoder Free Operation, CAMEL, Generic User Profile, Wireless LAN - UMTS interworking and descriptions of IP Multimedia Subsystem, SIP Call Control, SDP protocols for the IM subsystem, mapping of QoS and the interfaces specific to the UMTS Open Service Access (OSA).

Terms of reference

The latest terms of reference were approved at CT#36
in document CP-070500.

The technical specification development work within 3GPP is accomplished by Technical Specification Groups (TSGs) according to the principles and rules contained in the Project reference documentation (Partnership Project Description, Partnership Project Agreement, Partnership Project Working Procedures).

In particular the TSGs report to the Project coordination Group (PCG), and may organize their work in Working Groups and liaise with other groups as appropriate.
Each TSG has the responsibility to develop, approve and maintain the specifications within its terms of reference.

The TSG Core and Terminals (TSG CT) is responsible for specifying the Core Network and Terminal Equipment aspects of systems based on 3GPP specifications.

Specifically it has a responsibility for:

  • User Equipment - Core network layer 3 protocols in CS and PS domain excluding the access technology layers.
  • Core Network internal interfaces for Call Associated and Non Call Associated signalling
  • Interconnection of the Core Network with external networks
  • SIM/USIM/ISIM and its interface specifications
  • Terminal or Network based applications supported by 3GPP terminals
  • Core network protocols for CS and PS domain in legacy and evolved 3GPP system
  • IP Multimedia subsystem
  • Management of the work items placed under its responsibility
  • More specifically, TSG-CT will address the following areas of work in legacy and evolved 3GPP system :
  • CS and PS domain Mobility management for 3GPP defined access technologies, call connection control and session management signalling between the user equipment and the core network,
  • Core network signalling between the core network nodes. The signalling supports functionality such as user information, subscription information and control of network services.
  • Interoperability between 3GPP networks (e.g. handovers).
  • Interoperability between 3GPP networks and external networks (e.g., WLAN, non-IMS SIP, PSTN)
  • Packet related matters such as mapping of QoS [e.g. transparency for IP domain applications, general for bearer types, special for optimized applications such as Voice over IP].
  • IP Multimedia signalling protocols and adaptation of IMS to different access technologies
  • Protocol aspects of Core network interfaces.
  • Core network O&M requirements.
  • Service capability protocols,
  • Core network or terminal aspects of applications such as messaging or content sharing
  • Services end-to-end interworking,
  • SIM/USIM/ISIM to Mobile Terminal interface and functionality,
  • Model/framework for terminal interfaces and service (application) execution
  • Multi-mode terminals
  • Liaising with other TSGs and other fora as appropriate.

Glossary of terms

IMS IP Multimedia Subsystem
IP Internet Protocol
O&M Operations and Maintenance
QoS Quality of Service
PSTN Public Switched Telephony Network
SIM/USIM/ISIM Subscriber Interface Modules
CS domain Circuit Switched domain
PS domain Packet Switched domain
WLAN Wireless Local Access Network

Useful links and information

About TSG CT List of elected officials
Documents Meeting documents
Meetings Next meeting information & previous meeting reports and documents
  Liaisons Statements
  Full CT meeting calendar
General info 3GPP IETF Dependencies - from TSG#52 Jun 2011 onwards the 3GPP-IETF Dependencies are included in the 3GPP Work Plan
  Email exploder lists
CT Working groups 
TSG CT Plenary  
TSG CT WG1 User Equipment to Core Network protocols
[No WG2] See ClosedTerminals Group 2 - Capability
TSG CT WG3 Interworking with External Networks & Policy and Charging Control
TSG CT WG4 Core Network Protocols
TSG CT WG5 OSA (Now transferred to OMA)
TSG CT WG6 Smart Card Application Aspects



OSA - Open Service Access

Group closed 2008-06; work transferred to Open Mobile Alliance Useful links and information Documents Documents area Meetings Previous meeting reports and documents Terms of reference (Historical – Work now done in OMA) CT5 develops Application Programming Interfaces (APIs) for the Open Service Access (OSA). The UMTS network provides these interfaces to facilitate service (...)


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