The iPhone Locations DB – Fun, but not Accurate

As a followup to my previous post about the (re-)discovery of the iPhone locations cache, the graphic above shows the apparent locations (of known mobile-phone masts and wifi) that were captured on my iPhone, over the last couple of weeks while I have been in Scotland. These were either independently detected by my iPhone and georeferenced using a built-in service, or, more likely as it turns out, the details of supposed nearby masts were downloaded by my iPhone from this service, based on its own location, in the hope they would subsequently be detected and allow for quick positioning.

The graphic is from my hacked version of iPhoneLocator, changed to show a higher density of dots and include the wifi data. I have superimposed on the map red lines showing where I’ve actually gone over the break. Some of the detected (or downloaded in the hope of detection) mobile-phone masts were over 40 miles away from where I actually was. Some of these may have been when I was on top of a Munro (i.e. over 3000 feet up) which therefore affords a good line of sight. Or simply, there were so few in the area, that details from the far-away ones were the best available to be obtained.

If I hadn’t drawn the red lines, you would probably be surprised to discover, for example, that I never went to Inverness during this trip (the big patch of yellow circles in the very top part of the map extract. I also never went along the various roads visible in the north, west or east part of the map, but my phone still saw the towers in these locations. So to conclude, take the detected locations with a pinch of salt. They tell you where an external database thinks a cell-phone tower once was, or where the nearest few are, even if they are a long way away. They certainly don’t tell you where you’ve actually been…