Callserve chose Internet World yesterday to debut its revolutionary handset-based voice-over-Internet (VoIP) protocol solution.

Webphone offers cheap long distance calls from an online USB computer. Though the solution is currently available only for PCs, PR manager Gareth Strangemore told Macworld that Mac support "is two months down the line".

The technology converts analogue voice-data into digital data, and transmits this over the Internet. The handset attaches to the USB port, and the company claims it offers calls without background noise or interference.

The £39 Webphone USB handset will appear at high-street electrical stores "within weeks", says Callserve. It will ship with a £15 call voucher in the box and drivers, which are available for download from the company's Web site.

The company is offering savings of up to 90 per cent on rates charged by national carriers on long-distance. Paul Duffy, Callserve's managing director, said: "The technology uses the power of the Internet to enable incredibly low-cost phone calls to any fixed or mobile phone, anywhere in the world, at any time."

The call rate is 2p per minute to most European destinations all day, each day. The company is offering a call charge of 3p per minute to the US. There are no monthly charges, and calls are charged to a credit card.

The company has also launched a pre-paid calling-card service, Phoneserve. Subscription-free, this solution lets users make calls using borrowed computers, friendly Internet cafes or their own computer – though the Callserve software must be installed on whatever machine they use.