The 3G version of SMS will handle voice, images and video as well as text. But limited network coverage and storage issues may delay its uptake, says Bill Pechey
The staggering popularity of the GSM Short Message Service (SMS) has been an unexpected success story. Huge numbers of text messages are sent every day, and the charge of 10p or so per message is a welcome addition to the telecoms carriers' revenues from voice traffic.
It was a wise decision by the European Telecommunications Standards Institute (ETSI) to make SMS a mandatory feature in all GSM mobiles almost from the start. The success of SMS has lead the Third Generation Partnership Project (3GPP) to make sure that third-generation mobiles and networks will have a rich set of messaging features.
The 3GPP specification 23.140 describes the new Multimedia Messaging Service (MMS) and will be included in all the first 3GPP networks. MMS will be able to handle more than short text messages. The first implementations will support text, voice, image and video.
An MMS message can contain several different types of information, though it is likely that the simpler types, such as text only and voice only, will be more common than video. MMS will work in much the same way as SMS, in that the sender of a message will compose it on their mobile, enter the destination address and send it to the net- work service centre. MMS messages can be delivered directly to the recipient's mobile, but in many cases a notification message will be sent first which gives the option of delivering the message immediately or deferring it.
Some messages such as video clips will be very large and too big to be stored on a small mobile terminal. In these cases, a user could choose to have the message played to the terminal over the radio link rather than having it delivered for viewing later.
The implementation of MMS is largely based on existing standards such as SMTP and Mime, which means feature-rich implementations will be delivered more quickly, and compatibility with existing systems should be ensured. By using Mime, MMS messages can be sent to email addresses as well as to mobiles, and email programs will see the message parts as separate attachments that can be opened on a PC.
Almost all the features of MMS are independent of the method of conveying the messages, and we may see subsets of MMS services appearing in GSM networks. If this happens, it will be a useful test of implementations and the reaction of users. While 3G mobile networks are being built up, it will be essential for MMS to be carried over GSM so that 3G users do not lose their message facilities once beyond the limited regions of 3G coverage.
It will be interesting to see whether mobile users take to the MMS features with the same gusto as SMS. I suspect the still image service could be popular, but the video clip idea may take a while to catch on, especially as the early terminals may not have very large video storage capabilities.