Although more and more wireless telephone operators are providing services beyond pure voice telephony, such as short message service (SMS) and Internet access, most of these operations are still based on the so-called second-generation (2G) wireless telephone technology, with limited data rates (below 14.4 kilobits per second). First launched in Japan in 2001, the emerging third-generation (3G) mobile wireless networks are based on packet-switched communications (versus circuit-switched communications, as in earlier generations), and support services like video telephony and broadband multimedia applications, such as music downloading, online game playing, and live television and movie viewing. The 3G mobile technologies raise the channel carrier width to five megahertz, offering much higher data rates and increased capacity (transmissions between 64 to 384 kilobits per second for mobile systems and up to two megabits per second for stationary systems).

In general, mobile wireless networks share with existing fixed telecommunication networks--such as the public switched telephone networks (PSTNs) as well as the packet switched public data networks (PSPDNs), including the Internet--for connections among their base stations or radio towers. The vision of an entirely Internet protocol (IP)-based 3G standard by the Third Generation Partnership Project (3GPP) and the Third Generation Partnership Project 2 (3GPP2) had to be pushed out, due to the reality of today’s IP network (slow transition to the new version of IP version 6). This leads to the role of 3G-324M, which supports real-time multimedia wireless communications over a circuit-switched network, that is, the land-based telephone network.

As an umbrella standard for video telephony in 3GPP mobile networks, 3G-324M provides functionality for a variety of mobile voice and video services beyond video telephony, including multimedia messaging, video streaming, real-time gaming, video conferencing, remote monitoring, and surveillance. After a short introduction in section 1, a summary of the 3G-324M standard is presented in section 2. Section 3 deals with dynamic conversion of the content, and discusses the issue of media adaptation and transcoding (for example, encoding format, video size, and content organization so that the content can be presented based on the capabilities of terminal devices and user preferences, while the content semantics are kept as close as possible to the original). Sections 4 through 6 cover the support of 3G-324M for video call answering and messaging, video streaming, and video portals. Some extensions and clarifications for 3G-324M are proposed in section 7, and section 8 concludes the paper with a short remark.

With the field full of acronyms, technology standards, and international partnerships, this paper offers a quick and straightforward overview of the 3G-324M standard and its roles in various mobile multimedia services. The proposals for some extensions and clarifications of 3G-324M can be especially valuable references for people who are developing or implementing applications based on 3G-324M, and for those who are working on multimedia services for mobile wireless platforms.