While a phone doesn't need a cell tower for GPS, they for the most part need one for viewing their location on a map, and I think that's why people say they need a cell tower for their phone's GPS.
Long story short, my wife and I were trying to find the house we were crashing at in upstate New York one evening after a piece of hers was performed at Bard. I'd punched the address into my iPhone and off we went. Only in the last few turns did we realize that Google couldn't find the address and auto-corrected us to the wrong county (UGH). We tried entering the address again, but had no signal. We were only using the iPhone because we couldn't find my Garmin. Later when we returned home, we still couldn't find our Garmin, so I bought a newer one, refurb, off Amazon for ~$150. It tells me the speed limit of the road I'm on, shows me which lane I'll need to be in when a turn's coming up, acts as a bluetooth speakerphone and interface for my iPhone, gets traffic updates and gas prices from some kind of FM broadcast service.
Yes, convergent mobile devices will get there eventually, but there are still benefits to specialized devices.
This just is not true. The cell tower isn't needed for GPS. When you say you need a tower to see yourself on the map, that's the same thing as saying you need a tower for GPS.
If you mean you need the network connection for the maps, this is only true for the Native Maps app (which even does some caching). There are many, many apps that let you store maps offline (including my own).
Whenever I've tried my iphone 3G's gps that had absolutely no gsm/3g reception from any carriers in the area, the phone cant get my location at all, even in a car or an open air beach.
