| CN | CN1 | CN2 | CN3 | CN4 | CN5 |
| CT | CT1 | CT3 | CT4 | CT5 | CT6 |
| GERAN | GERAN1 | GERAN2 | GERAN3 | GERAN4 | GERAN5 |
| RAN | RAN1 | RAN2 | RAN3 | RAN4 | RAN5 |
| SA | SA1 | SA2 | SA3 | SA4 | SA5 |
| T | T1 | T2 | T3 |

TSG  CT WG4 (MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN)

Overview:

The TSG Core Network and Terminals WG4 (TSG CT WG4) standardizes stage 2 and stage 3 aspects within the Core Network focusing on Supplementary Services, Basic Call Processing, Mobility Management within the Core Network, Bearer Independent Architecture, GPRS between network entities, Transcoder Free Operation, CAMEL, Generic User Profile, Wireless LAN - UMTS interworking and descriptions of IP Multimedia Subsystem. CT4 is also responsible as a "protocol steward" for the some IP related protocols (this involves analyzing, validating, extending if necessary, clarifying how they are used, specifying packages and parameter values).