From your comment, it sounds like you are seeing a different position on your map when you use wireless networks (cell / wifi) or GPS.
Firstly, wireless networks can give very accurate positions depending on how much georeferencing data was available for your area – within 2-3 metres, which is as good as most GPS fixes.
That said, there are a few things that come to mind:
- The GPS is having difficulty getting a good position due to poor sky view, and/or interference from buildings or other sources (some recent discussion of this on GIS.se if you search). If the GPS fix is poor, then the application may just ignore it and use the wireless fix only.
- The GPS might be right, and both the map you're seeing and the wireless fix wrong!
If you're in a city in Europe or North America, then (1) seems likely - interference from buildings, yet lots of wifi/cell towers to give you a good wireless fix. Otherwise I might suspect (2) – I know that Google Maps is off by 20-150m for most of the city where I live in East Africa, and there is not enough cell tower or wifi georeference data for our area to give good fixes.