cell phone has GPS and uses satellite positioning, it also use augmented location via cell tower
the problem arises(using google maps) when you no longer have a data signal connection to get the map data for your location, the phone has the co-orientates, but no map data to show you the location
there are GPS mapping programs that will download and store map data
but its NOT automatic, you have to choose the areas and have that program DL that data for the maps, before you travel to an area with no cell signal
for people that really depend on GPS, buying a dedicated GPS is a good idea
i like having a map app to show me where i am on the highway
but i prefer real paper maps for route planing
and i don't use turn by turn directions
tried a couple of times, did not like it
i trust my self and paper maps, a lot more than a computer giving me directions