Satellite navigation (sat nav) comes various forms. The most common, and indeed easiest to use, are the standalone systems such as the Evesham Bluemedia BM6380 and the Navman ICN510.

However, there are also various sat nav systems that will run on your phone. Mobile 7 is the latest from Route66 and is designed for Symbian Series 60 phones.

Using your mobile phone as the basis for a sat nav system is always going to have its drawbacks, with screen size being the obvious one.

We tested Route66 Mobile 7 on a Nokia N70, which has a diagonal screen size of 2in. Although the display is certainly viewable, we wouldn't recommend attempting to look at the map while driving.

The standard package consists of a 256MB RS-MMC (Reduced-Size MMC) and a Sirf Star III Bluetooth GPS receiver. You also get a cradle and charge for in-car use.

Installation isn't a problem and is simply a case of inserting the card into your phone and then registering the software - this can be done via SMS. You'll then need to pair your phone with the Bluetooth receiver.

Unlike Navicore Personal 2006/1, a similar sat nav system for mobiles that uses Tele Atlas maps, Route66 Mobile 7 employs the more popular Navteq alternative.

We tested the system out on variety of trips and each time it managed to get us from A to B without any hiccups. As expected, it recalculated routes when a turning was missed. Inputting post codes using the phone can get a bit fiddly, but on the whole the system works well.

Impressively, road traffic updates can automatically be over a GPRS connection. Although Route66 doesn't charge for this service, your phone operator may well charge you for data usage.

We found our Nokia N70's battery to drain pretty fast when running Mobile 7.

Although you can always plug it into your car power adapter socket during use (this requires an in-car charger for your mobile), if the Bluetooth GPS unit also needs charging you're in trouble.

It's also expensive. If you already have a Bluetooth GPS receiver, you can by the software only for €99 (£67 approx), but the full package costs €299 (£205 approx). Various other packages with additional European maps are also available.

If you don't like the look of the budget standalone sat nav devices and want a system you can carry around with you wherever you go, Route66 Mobile 7 performs well enough.

Check out the Route66 website for supported handsets.