Vodafone remains the market leader with 1.8 million users, while Cellnet has 1.74 million. Howard Ford, managing director of Cellnet, said: "I am confident that Cellnet will achieve a dominant percentage of the forecast 10 million mobile customers in the UK by the end of the decade."
Richard Goswell, managing director of One2One, said that the growth in the overall market is driven by consumers - now accounting for two thirds of new subscriptions - rather than business executives.
Mr Goswell denied speculation that many of One2One's customers use the service primarily for its free off-peak local calls. The company said that these "free call abusers" account for only 4 per cent of the company's customer base.
One2One is also planning a range of new packages this year in an attempt to secure more high-paying business customers. The company is talking to Mercury about the possibility of offering joint packages of fixed and mobile services.
Mr Goswell called on the regulator, Oftel, to prevent any abuse of market dominance by BT.
He envisages BT working closely with Cellnet, in which BT has a 60 per cent stake, offering combined mobile and fixed bills, and said that he is worried about the ability of BT to exploit its market power.
Mr Goswell said that BT and Cellnet are already conducting trials in the London area. "I personally expect it to result in a service that will be marketed. It is the packaging of services - fixed and mobile - which we believe is key to the UK telecommunications sector into the next century," he said.