4 General

26.1103GPPCodec for circuit switched multimedia telephony serviceGeneral descriptionRelease 17TS

3G-324M terminals provide real-time video, audio, or data, in any combination, including none, over 3GPP circuit-switched, radio networks. They are based on ITU-T H.324 with Annex C, and Annex H when mobile multilink operation is supported. Communication may be either 1-way or 2-way. Such terminals may be part of a portable device or integrated into an automobile or other non fixed location device. They may also be fixed, stand-alone devices; for example, a video telephone or kiosk. 3G-324M terminals may also be integrated into PCs and workstations.

In addition to 3G-324M to 3G-324M communication, interoperation with other types of multimedia telephone terminals is possible, however a gateway may be required.

Multipoint communication between more than two 3G-324M terminals is possible using a Multipoint Communication Unit (MCU). MCU functionality is for further study.

3G-324M terminals are based on ITU-T H.324 with Annex C, and Annex H when mobile multilink operation is supported. For performance reasons and to reference the call set-up procedures, some modifications to H.324 were made. These are described in 3GPP TS 26.111, except call set-up procedures are described in 3GPP TS 24.008, 27.001, 29.007 and 23.108. 3G-324M terminals shall conform to these specifications. Because of the many options in H.324, an implementor’s guide, 3GPP TR 26.911, provides preferred options for 3G-324M implementations.

Figure 1 below shows the functional components of a generic 3GPP multimedia terminal. The video, speech, data and multilink components are optional. If a media type is supported, the standards indicated are mandatory except those enclosed in square brackets are optional.

Figure 1 Scope of circuit switched multimedia 3GPP specification. Items in [brackets] are optional.

Short descriptions of ITU-T H.324, 3GPP TS 26.111, and 3GPP TR 26.911 are given below.