Cellnet will launch the Internet service next month, to be called Genie Internet, which will mimic existing offerings such as Dixons' Freeserve by not charging a monthly subscription fee.
The service will initially be targeted at young customers of its "U" pay-as-you-go service, but will shortly be extended to all other users, who will be sent a CD-Rom containing the required software.
Customers who sign up to the service will receive an email address and access to a web site offering a range of news and information. They will also be able to set up a messaging system, which sends brief text messages to their mobile phones alerting them to news flashes, sports scores, or the arrival of a new email.
The move is a precursor to the arrival, probably later this year, of mobile terminals that will allow users to access the Internet over a mobile phone network.
"We clearly see the markets of data and mobile coming together and we want to be first,'' said Peter Erskine, Cellnet's managing director.
The move is also designed to discourage customers from defecting to other networks following the introduction last month of number portability in the mobile phone market.
At the moment, mobile phone networks are too slow to be able to send or receive large volumes of data. However, Cellnet is planning to upgrade its network with new software next year, which will allow data to be transferred at the same speed as the fastest fixed-line modem.
The introduction of the third generation of mobile phone networks in three to four years' time is expected to make mobile Internet access and electronic commerce widespread.
Cellnet is currently in talks with Microsoft, which recently formed a strategic alliance with Cellnet's majority shareholder British Telecom, and Symbian, the joint venture between Psion and the world's leading mobile phone manufacturer, about what form the new Internet-enabled handsets will take.
The Genie website has been up and running for 18 months, but has only attracted 100,000 users from its customer base of 3.5m.