THE internet has revolutionised home phone calls, with services such as Skype offering free calls. Now the technology is moving to mobile phones.

Last week, two firms, Leeds-based Mobiboo and the US giant Belkin, launched mobiles that send and receive calls over the internet using a wireless connection (wi-fi), bypassing the traditional mobile networks and their high costs.

Calls on the same network are free anywhere in the world.The Belkin phone connects to the Skype network while Mobiboo uses The Cloud.

The technology, known as voice over internet protocol (Voip), is installed in more than 1.8m households in Britain with a market estimated at £77m, according to Ovum, an analyst.

The Skype Voip network has more than 100m users worldwide, although it faces a challenge from household names such as Tesco, which offers its own internet call packages.

Until recently, Voip users had to make calls either through a wi-fi laptop, or a PC with a broadband connection, along with a headset costing about £15. Now you can access wi-fi networks using a new generation of mobile handsets.

The Mobiboo F1000 handset costs £99, while the Mobiboo F3000 will set you back £179. Once you have the handset, calls to Mobiboo users are free, while calls to other landlines are much cheaper than with traditional mobiles. Calls to non-Voip mobiles are competitive but not glaringly cheap, though.

Mobiboo charges 2p a minute for calls to UK landlines and from 14p to non-Voip mobiles. By contrast, an O2 pay-as-you-go customer pays 35p a minute for calls to landlines during the day and 20p a minute to mobiles. T-Mobile’s pay-as-you-go tariff is cheaper for calls to other mobiles at 12p a minute.

With the Belkin wi-fi handset (£120) calls to other users, including those who have Skype at home, are free. Landline calls are charged at 1.4p a minute while calls to other mobiles cost 16.6p.

The biggest savings come with international calls. A call to an Australian or French landline costs 2p a minute using Mobiboo and 1.4p a minute using Belkin, rather than £1.50 if you made the call using O2 pay as you go, or £1 using T-Mobile. Calls made while abroad cost the same as at home.

The disadvantage of the Mobiboo and Belkin is that they only work in areas with wireless access, or “hotspots”.

If you receive a call outside of a hotspot, it will go straight to voicemail. And if you wander out of a wi-fi area during a call, the line will be cut off, in the same way as a mobile loses network coverage.

Richard Newsome of Mobiboo admits the drawbacks: “It’s not as ubiquitous as cellular. You won’t be able to use it driving up and down the M1, even with a hands-free kit.”

Mobiboo is targeting cities with extensive wi-fi, such as London, Norwich and Bristol. Newsome said: “In London you are probably never more than 100 metres from a hotspot.”

To make the service more reliable, Mobiboo has tied up with The Cloud, Europe’s leading hotspot provider, which boasts 7,000 hotspots across Britain.

Analysts say wireless internet access will improve because of new technology, wimax — wi-fi with a greater range.

Another problem is the lack of compatibility between Voip providers. Mobiboo users will not be able to make free calls to people using other Voip services such as Skype. Instead they will be charged 2p a minute, the same as a landline call.

The problem is less acute for the Belkin phone because of the extensive use of Skype around the world. And it is thought Voip companies are in talks to establish “peer-to-peer” networks next year. This would allow different Voip services to use rival networks for free.

Mobile-phone network operators are understandably wary, though. Some companies, such as T-Mobile, warn customers that they will have their internet access restricted if they find Voip calls being made on their internet-capable handsets.

Mobiles using 3G technology to connect to the internet cannot use Voip because access is controlled by the mobile operators.

Not everyone is confident Voip will be a success. DSG International, formerly known as Dixons, last week pulled out of the market — less than 12 months after launching its Freetalk service with great fanfare.