I'm making an application that authenticates based on location. For example, you can set a particular location (coordinates) as 'secure location' and when the phone comes within a certain distance of that location, the authentication is said to be successful. I will use GPS for this.
My questions are : 1. Is GPS reliable enough and accurate enough to accomplish this task? 2. In case the GPS lock isnt available, is it possible to get approximate co-ordinates using the cellular or 3G internet? If so , how accurate will it be ? 3. Can you see any other issues with this idea? Thank you.