3G-324M is the 3GPP umbrella protocol for video telephony in 3G mobile networks. The 3G-324M protocol operates over an established circuit switched connection between two communicating peers. 3G-324M is an umbrella specification to enable conversational multimedia communication over Circuit Switched (CS) networks and has been adopted by the 3GPP. 3G-324M is based on the ITU-T H.324 specification for multimedia conferencing over Circuit switched networks. 3G-324M is composed of the following sub-protocols: ITU-T H.245 for call control ITU-T H.223 for bit streams to data packets multiplexer/demultiplexer ITU-T H.223 Annex A and B for error handling of low and medium BER detection, correction and concealment ITU-T H.324 with Annexes A and C for operating in wireless environment The 3G-324M specification using the Circuit switched network allows delay sensitive conversational multimedia services such as: Videoconferencing for personal and business use Multimedia entertainment services Telemedicine Surveillance Live Video Broadcasting– Cable TV On-the-Go Video-on-demand (movies, news clips) 3G-324M is agnostic to the actual Circuit switched network that uses it. It can run as easily over UMTS as well as TD-SCDMA networks. 3G-324M operating over a circuit switched channel between two communication peers guarantees the fixed-delay quality of service for multimedia communications. Combining Circuit switched 3G-324M services with packet-based SIP services such as presence can leverage the strength of both networks to enable new types of differentiated and innovative mobile 3G services. Codecs Audio Codec GSM Adaptive Multi-Rate, mandatory AMR-WB (G.722.2), optional ITU-T G.723.1, optional Video Codec ITU-T H.263, mandatory ITU-T H.261, optional MPEG-4 part 2 simple profile 1 level 0, optional ITU-T H.264, optional References External links 3GPP TS 26.111 - Codec for circuit switched multimedia telephony service; Modifications to H.324 IMTC 3G-324M AG - Interoperability and testing activity group covering the 3G-324M and H.324 protocol 3G-324M on Windows Mobile - An interesting article on the integration of 3G-324M into a Windows Mobile operating system Understanding the 3G-324M Spec - A good explanation on the specification of 3G-324M Videotelephony Application layer protocols