I was curious about using GPS without a cell signal. :-/

I found this on some I-Phone forum.


Quote:

Most phones use the cell network to get a rough idea of where you are (I say rough, but really it cuts it down to a tiny area compared to the size of the Earth aka the coverage of GPS) then use GPS to get the exact location. So if your out of cell range it can take something like up to 20 minutes to get the location (although that was on a Samsung phone and I noticed the iPhone is faster at GPS anyway) The Apps have a accuracy setting so it's possible that if the accuracy is not accurate enough to use GPS it won't find your location, however I would've thought it would find your location with GPS once it realizes there's no data connection. Turning my iPhone onto AirPlane mode (effectively taking it out of range of any data connection) and then going onto the default maps app and finding my location takes a while, and switching app while it takes this long makes it timeout.