IP Multimedia Subsystem (IMS)

IMS, or the IP Multimedia Subsystem, is the part of the 3G mobile networks responsible for providing multimedia services, especially voice, video, and data services.

IMS was created by 3GPP, the internationally recognized standards forum for defining the third generation mobile phone network. IMS provides an interoperable means of roaming, provides bearer control, and addresses billing and security requirements.

IMS is based on the IETF Session initiaion Protocol (SIP). As such, the primary functionality provided by IMS is voice and video services, though service providers will also use the system to allow users to exchange pictures, chat, etc. IMS also supports a multiplicity of access types, including GSM, WCDMA, and CDMA2000.

Resources: 3GPP, Ericsson White Paper

See Also: 3GPP