GPS can fail to find the exact location of a device if too many material obstructions are in the way of the satellite signal. The most common places for GPS to fail are in hospitals or metal roofed office buildings. When the GPS application fails to get a clear reading of the latitude and longitude, the app will then send the user the network based location of their device. The network based location is the location of the closest cell tower to the device and could be several miles away from the actual location. Satellite locations are constantly changing because of the curvature of the Earth so if the GPS fails to get the exact location try again at a different time during the day.