Imagine a mobile phone you don't have to pay to use. That is the lure of Three's Skypephone, which can be used to make voice calls over Skype and use Skype's instant messaging service. The person you are calling or IM-ing doesn't need a Three Skypephone, just a Skype account (for Voice over IP - video calling is not supported here).

It sounds like an ideal proposition for someone with relatives in far flung parts of the world, or someone who just wants to try to beat the mobile operator on call charges.

But you don't get anything for nothing, and there are still charges to pay. The phone is available on contract or Pay As You Go. If you are on contract you can use the Skype part of the phone for no extra charge. On PAYG you need to pop £10 a month or more into the phone, regardless of how much money you've actually spent on calls. You can get the phone for free on contract, £50 on PAYG.

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The phone itself is a neat little 3G handset. It measures 100 x 44 x 13.6mm and weighs 86g. It is available in white or black. The casing is plastic, and it feels reasonably good in the hand.

The screen is fairly small at two diagonal inches, and pretty low resolution at 176 x 220 pixels. Under the screen, the centre of the navigation button is the large key you press to initiate a Skype call or IM. The Skype software is very easy to use: anyone who has used the desktop version should have no trouble getting to grips with it.

You also have the required software to synchronise the phone's calendar and contacts with a PC, and the phone works in Mass Storage mode, which means you can just plug it in and copy some files across to it. The main example that springs to mind here is music.

There is 16MB of internal memory for file storage and a microSD card slot under the battery. You get a 256MB card with the phone. A music player is built in, and the phone does a reasonably good job of playing tunes.

There is no front-facing camera for video calling, which is a bit annoying. The 2-megapixel camera on the back of the casing is average, not outstanding.

All in all, without the Skype features we'd rate this handset as low-end to mid-range, and no better. With the Skype capability it becomes something rather different to your run-of-the-mill mobile phone, but anyone looking for much more in the way of other features may be disappointed.

Skype addicts may like the idea of being able to use the service away from a computer, but anyone looking for a sophisticated mobile phone will be disappointed.