4G/5G
IMS
IP Multimedia Subsystem
Rel-8 (2008)
Overview
The access-agnostic subsystem delivering VoIP, VoLTE, VoNR, and multimedia services over IP.
Full technical content for IMS is coming soon. In the meantime, browse the related specifications below.
Specifications
TS 23.228
IP Multimedia Subsystem (IMS); Stage 2
Architecture
Rel-17TSIMSUpdated 2026-07-25
TS 23.216
Single Radio Voice Call Continuity (SRVCC); Stage 2
Architecture
Rel-16TSIMSUpdated 2026-07-25
TS 24.007
Mobile radio interface signalling layer 3; General Aspects
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.008
Mobile radio interface Layer 3 specification; Core network protocols; Stage 3
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.010
Mobile radio interface layer 3; Supplementary services specification; General aspects
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.011
Point-to-Point (PP) Short Message Service (SMS) support on mobile radio interface
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.022
Radio Link Protocol (RLP) for circuit switched bearer and teleservices
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.030
Location Services (LCS); Supplementary service operations; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.067
Enhanced Multi-Level Precedence and Pre-emption service (eMLPP); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.072
Call Deflection (CD) supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.080
Mobile radio interface layer 3 supplementary services specification; Formats and coding
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.081
Line Identification supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.082
Call Forwarding (CF) supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.083
Call Waiting (CW) and Call Hold (HOLD) supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.084
Multi Party (MPTY) supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.085
Closed User Group (CUG) supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.086
Advice of Charge (AoC) supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.087
User-to-User Signalling (UUS) Supplementary Service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.088
Call Barring (CB) supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.090
Unstructured Supplementary Service Data (USSD); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.091
Explicit Call Transfer (ECT) supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.093
Completion of Calls to Busy Subscriber (CCBS); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.096
Name Identification supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.103
Telepresence using the IP Multimedia (IM) Core Network (CN) Subsystem (IMS); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.105
Application specific Congestion control for Data Communication (ACDC) Management Object (MO)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.109
Bootstrapping interface (Ub) and network application function interface (Ua); Protocol details
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.116
Stage 3 aspects of system architecture enhancements for TV services
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.117
TV service configuration Management Object (MO)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.135
Multicall supplementary service; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.139
3GPP system - fixed broadband access network interworking; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.141
Presence service using the IP Multimedia (IM) Core Network (CN) subsystem; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.147
Conferencing using the IP Multimedia (IM) Core Network (CN) subsystem; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.161
Network-Based IP Flow Mobility (NBIFOM); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.166
3GPP IP Multimedia Subsystem (IMS) conferencing Management Object (MO)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.167
3GPP IMS Management Object (MO); Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.171
Control Plane Location Services (LCS) procedures in the Evolved Packet System (EPS)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.173
IMS Multimedia telephony communication service and supplementary services; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.174
Support of multi-device and multi-identity in the IP Multimedia Subsystem (IMS); Stage 3
Protocol
Rel-16TSIMSUpdated 2026-07-25
TS 24.175
Management Object (MO) for multi-device and multi-identity in the IP Multimedia Subsystem (IMS)
Protocol
Rel-16TSIMSUpdated 2026-07-25
TS 24.182
IP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT); Protocol specification
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.183
IP Multimedia Subsystem (IMS) Customized Ringing Signal (CRS); Protocol specification
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.186
IMS Data Channel applications; Protocol specification
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.193
5G System;Access Traffic Steering, Switching and Splitting (ATSSS); Stage 3
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.196
Enhanced Calling Name (eCNAM)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.216
Communication Continuity Management Object (MO)
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.229
IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3
Protocol
Rel-20TSIMSUpdated 2026-07-26
TS 24.237
IP Multimedia (IM) Core Network (CN) subsystem IP Multimedia Subsystem (IMS) service continuity; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.238
Session Initiation Protocol (SIP) based user configuration; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.239
Flexible Alerting (FA) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification
Protocol
Rel-15TSIMSUpdated 2026-07-25
TS 24.244
Wireless LAN control plane protocol for trusted WLAN access to EPC; Stage 3
Protocol
Rel-15TSIMSUpdated 2026-07-25