The unpredicted popularity of text messaging, or SMS (short message system), has been accredited mainly to teenagers, who discovered the technology as a cheap alternative to mobile calls.

But there's a new service about to become available that may replace text-only messages.

That service is MMS (multimedia messaging services), which promises to allow mobile device users to send pictures, sound and even video between devices.

O2's PDA-phone, the xda, is out imminently and can do MMS, as can Ericsson's T68 and Nokia's 7650 MMS compatible handsets. Motorola and Siemens look set to launch their terminals during the latter half of this year.

"Combining both [mobile and PDA] is just a logical next step," said O2's spokesman.

But MMS depends on a lot more than SMS did, including worthwhile content and higher-capacity networks.

"The success of MMS is reliant on the successful rollout of GPRS [general packet radio service]," says telco watchdog Oftel. "Manufacturers must realise users are only interested in products they can use, content that's available now and not what will be available in the future."

A separate study by researchers at Forrester has revealed a huge rise in the number of people accessing the internet via web-enabled PDAs across Europe, rising from seven million in 2000 to 302 million this year. Mobile phone ownership is almost at saturation point, with 70 percent of Europeans now owning a mobile handset.

The sudden boom in text messages, with an average of 43 million sent each day in the UK according to the Mobile Data Association, was largely unexpected by service providers which had little idea that SMS would prove so popular.

"The beauty of SMS is that people basically adapted it themselves; it took a more home-grown approach. Instead of setting down a series of promises it has developed [now including games and picture downloads] through use," said a spokesman at mobile telco Vodafone.

SMS services are primarily used for person-to-person services, accounting for 95 percent of all messages sent today.

But the problem with SMS is that it is limited to basic text and cannot support the colourful animations and multimedia offered by MMS, which is why, research firm Frost & Sullivan predicts, SMS figures will begin to drop by 2005.

MMS relies largely on quality content and its success, according to Frost and Sullivan, will rely on low pricing and a sustainable business model between network operators, service providers, content providers and equipment vendors.