O<2 and Vodafone have linked their networks in a move that will enable their subscribers to send multimedia messages and photographs to mobile users who subscribe to the rival network.

The State's two biggest mobile phone companies are currently testing the network technology and plan to formally launch the new link-up for all their subscribers from next month.

Until now, consumers who have purchased the latest generation of mobile handsets have been unable to send photographs or multimedia messages to users who subscribe to a rival network.

Analysts believe this has slowed the uptake of multimedia messaging services (MMS), the latest mobile technology which enables users to send pictures, sound and text in one message.

Vodafone and O2 launched their multimedia messaging in November in the crucial run-up to Christmas, but both have so far refused to reveal how many Irish people are using the service.

Industry experts believe just 20,000 multimedia-enabled handsets have been sold in the Republic. Therefore, only a small number of picture messages are sent each month due to the small number of handsets and because users can only send messages to customers on their own network.

Ms Danuta Gray, O2 Ireland's chief executive, said yesterday the interconnect agreement planned for April would be an important factor in getting the new service to take-off point.

She said the delay in connecting the Vodafone and O2 networks until now probably hadn't been a big factor. But if this had gone on for another nine months, it would have been an inhibiting factor, said Ms Gray. Vodafone would not comment on when full "network interoperability" would be achieved. But it confirmed the firm was engaged in tests and network trials with O2.

Multimedia messaging is tipped to be the next big thing and should increase mobile firms' average revenue per user.

This average revenue figure is the amount of cash that firms generate from each subscriber and is used as a yardstick to measure a firm's performance. Mobile firms hope multimedia messaging will become as popular as text messaging as more users buy compatible handsets and firms link their networks to make them interoperable.

The State's third mobile firm Meteor has not launched a multimedia messaging service and is not party to the new interoperability agreement between Vodafone and O2.