GSM cells

Me and some of my colleagues have been busy with mapping GSM cell IDs to actual locations in terms of GPS coordinates (latitude, longitude). Currently, we have spotted a little more than 1000 cells, the top of the iceberg (see the database with maps), but the infrastructure is in place to do much more! The fun is of course that with this information you can supply a mobile caller with an estimate of his location, based on cell ID only. If you are willing to contribute to the data collection, you are welcome, you only need a Symbian phone (e.g. P800) and an Emtac GPS receiver.