Maarten Struys, a former DAD MVP, has published a whitepaper on Creating Location Aware Applications for Windows Mobile Devices.

This whitepaper doesn’t only cover GPS, but Cell Tower Lookup as well. Cell Tower Lookup is based on GSM, where a position can be retrieved by the according CellID. The pros and cons of each method are covered by the whitepaper as well. A sample application is also included.

As the sample application is using the Yahoo web service for retrieving the location based on the CellID, I’d suggest to take a look at Providers like CellDB and OpenCellID. Those providers don’t only enable (after registration) to request CellID locations, but also to upload new ones.

If you are especially interested in posting new CellIDs, than you probably shall take a look at the Open Cell Client.