A look at the accuracy of mobile phone tracking services for the Guardian, and the ethics in using them to track children. I have also written about how networks track users and how the technology is used by the emergency services.
Mobile phone tracking has become one of the hottest new mobile applications. Several services now allow users to track the location of mobile phones, with many making concerned parents their key market.
Many of the service’s new customers will undoubtedly have been persuaded to sign up because of the Soham murder trial. A vital piece of prosecution evidence was provided by mobile phone records that pinpointed the location of Holly Wells and Jessica Chapman outside the home of murderer Ian Huntley.
But despite such high-profile successes, there are question marks over the accuracy and security of the data provided to users. The location information comes from the mobile operators and, specifically, relies on which base station a phone is using to connect to its network.
For a switched-on mobile phone, whose owner has given permission, the networks will provide location data with up-to-the-minute accuracy – for a price. You will be able to see the precise location of the base station they are using, and a circle of accuracy within which the network believes the phone to be located. If the person being tracked uses the Vodafone network, you can even retrieve the last base station used by a switched-off phone, and the time of disconnection.
The problem is that base stations are sited to provide the best coverage, not to track the location of users. The circle of accuracy can have a diameter of a few hundred yards in a city centre, but several miles elsewhere. Vodafone and O2 use base stations with a maximum range of 35km (22 miles), and Orange and T-Mobile stations (the network used by Virgin Mobile) have a 17km range.
However, the geography of an area can cause strange readings. Richard Cox, a forensic expert in the field of mobile phone location, says he has seen a phone in Weston-super-Mare connect to a base station in Penarth, just south of Cardiff, despite much closer stations in north Somerset. “Anywhere with two coasts, or a valley, could do this,” he says.
Online found this effect when testing such a service using an Orange mobile phone. In the readings provided, the phone was within the circle of accuracy – but it was sometimes a rather large circle.
A test from Saltash, a sizeable town in Cornwall, showed the phone connecting through a base station in St Budeaux in west Plymouth, almost twice as far away as an Orange base on the Saltash side of the Tamar Bridge. However, there is a clear line of sight from the test location to that part of Plymouth. The resulting accuracy circle was 4.6 miles in diameter, which includes not only Saltash, but also half of Plymouth and the Cornish town of Torpoint.
The size of the accuracy circle is generated by the signal strength, which allows an estimate of the user’s distance from the base station. But it is not that accurate, and as a result one cannot say where the tracked phone is in circle. Despite the accuracy circle’s radius of 2.3 miles, the phone in Saltash was just 1.1 miles from the Plymouth station. A separate test in north Somerset, with a phone 1.3 miles from the base station, also produced a 2.3 mile radius circle.
The service tested was Mapaphone by Mapbyte, although all use the same data from the phone networks. Mapaphone only works on Windows PCs running Internet Explorer with Java Virtual Machine, and costs £10 a year for each mobile tracked, a £2.95 monthly subscription fee (which also provides access to mapping and information services) and 20p each time a location is requested.
Its rival ChildLocate charges £9.99 a month, but this includes up to eight mobiles and up to 10 location requests. Further requests cost 30p each.
“Cell ID tracking isn’t very accurate,” says Emma Hardcastle, managing director of Mapbyte. She says the service is aimed mainly at companies wanting to see when their vehicles will arrive, rather than parents. For the latter, she says that satellite-based global positioning system (GPS) products are more suitable, as they are accurate to within a few yards.
And the data available from base station services is nothing like as good as that available to police and other government investigators.
Mobile phones will eventually include GPS technology. But even releasing middling-quality location data raises privacy questions.
Mapbyte requires parents wanting to track their children, and employers tracking staff, to sign a form. In the case of children, the parent is then emailed a Pin, which they must enter into the child’s phone, to prevent strangers activating the service.
Mapbyte sends tracked mobiles reminder text messages, 24 hours after tracking starts then every month, stating who is tracking the phone and explaining how to opt out. ChildLocate sends such reminders every fortnight.
Privacy campaigner Spy.org.uk has questioned the security of these services, pointing out that several do not use encryption (although Mapbyte and ChildLocate do). The group also raises questions about the service providers’ staff, suggestingthey should go through criminal record checks.
Finally, there’s the question of whether parents should track their children. Terri Dowty, policy director of Action on Rights for Children, says: “I think this is a very destructive idea – a really cynical exploitation of parents’ fears. We all have to face letting our children go and trusting them. You can’t keep them on a lead forever.”
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