It is still a fledgling business but advertisers are queuing up to get their message across on new-fangled email phones.

Amstrad has told MediaGuardian.co.uk its new telephone service combining email and text messaging has just signed up its 25th client.

Simon Sugar, commercial director of Amstrad and son of entrepreneur Alan, said he was developing a number of new revenue streams for the Emailer product, and was in the process of expanding the advertiser base.

"As we update the software we can offer more targeted and premium services. We're still really in trial status but are starting to offer more advertising opportunities," said Mr Sugar.

One new "value-added service" launching this week is a greetings card facility allowing users to email electronic templates for birthdays and other anniversaries.

Other services in the pipeline are pre-loaded branded pizza menus, phone numbers and localised advertising.

This week Norwich Union joins the growing list of companies keen to try out the new medium.

Other big names signed up include Interflora, BSkyB, Direct Line, Britannia Music, Dixons, UCI Cinemas and Dial-a-Phone. The adverts typically flash up on the screens throughout the day and can carry direct phone call links to call centres.

Adverts stay on the service for up to eight days and cost between 15-25p per advert delivered.

So far 90,000 users have Emailer telephones while the cost of an eight-day campaign varies between £13,500 and £22,500.

Mr Sugar is trying to make Emailer pay its way to offset losses from drastic cost-cutting in the price of the units, which are sold at £79 even though they cost almost £200 to make.