O2 has changed its terms and conditions to allow it to share "...the date, duration, time and cost of such communications and the location of your mobile phone".

O2 will be sharing this information with credit companies, other telecommunications companies, and debt collectors "...for the purposes of operating your account and providing you with the service...in addition to crime prevention and fraud detection".

Knowing where you are, and where you're making calls from, enables the network operators to build their networks with appropriate capacity, but few mobile phone users seem aware that their location is not only being monitored at all times, but that that information is being archived for future reference.

The Data Protection Act stops companies sharing information about the movements of individuals without permission, but they are free to gather the information for their own usage, and to publish statistical studies, such as T-Mobile's recently published Mobility Trends report.

The report is no more than a snapshot of information from the T-Mobile databases, but it demonstrates just how much information mobile networks are able to gather about their customers and their movements.

It found that residents of Paisley are the most mobile of T-Mobile's customers, with only 21.3 per cent of calls being made from within their own postcode. Those living in Belfast, however, don't like to travel, or at least make calls when they are travelling, as residents made 92 per cent of calls from within their local area.

It should come as no surprise that Londoners don't travel much with over 83 per cent of calls coming from their home postcode.

According to the report, T-Mobile customers like to visit Romford (4.6 per cent of calls), Enfield (2.2 per cent) and Ilford (2.4 per cent), but they never make it up to the Shetlands, Kirkwall or Stornoway. ®