whjco wrote:
With a cell phone GPS app, you need to purchase a program that loads the map database onto the phone so that you'll have navigation in areas where there is no cell phone coverage.
I don't know about Apple but with Android devices that is only partly true.
The nav program automatically loads a limited set of maps depending on where you ARE and automatically "rolls" that set of maps as you move along. The actual GPS function does NOT depend on cell service and as long as you don't lose connectivity for too long, the maps don't either.
Unless your normal travel is somewhat unique, you do NOT need to purchase anything extra.