Cell ID Location Tracking
Using GPS based equipment is not the only way to find location data, it can also be found by triangulation using the cell towers that the mobile phone / GSM modem / GSM terminal has in range at the time. The original iPhone uses this method along with supplemented Wi-Fi data to locate the user on a Google map.
Also various commercial services such as FollowUs offer PAYG services for locating handsets without inbuilt GPS. For developers there are commercial services from Navizon, and Skyhook.
Along with the commercial services for those that only need Cell ID triangulation data for a specific area there may be the possibility of collecting the Cell IDs yourself with GPS / GSM capable equipment, then storing it in a database, and later using it to find out where users who only have phones are located by looking up the Cell IDs available from the user, and matching them to the database data to determine the GPS location.
There are a number of open source efforts to record / make available Cell ID location data which can also be used, these include:
- ZoneTag Cell Location API, Yahoo
- OpenCellID, 8Motions
- CellSpotting
However at the current time due to the large amount of data needed to make such services useful they are somewhat limited at the current time. Using data from all 3 could increase the likelihood of finding a location.
Further Reading:
- Adding location to a non GPS phone : using OpenCellID, 8Motions blog
- Sitefinder, Ofcom