[a_c_s]

It works with both...the stock configuration is aGPS which means it uses a combo of cell towers and satellite data to pinpoint your location...this obviously uses data, and in roaming areas or places with spotty coverage, would be a hit or miss solution...Sprint's built in Nav program works this way...BUT, there are some great options like Garmin XT, iGo 8 and Tom Tom all of which work really well on the phone and can work with pure satellite signals...my Garmin XT can use either aGPS or GPS...I let it start in AGPs mode and then turn off data and let it cruise in pure GPS mode...better on battery life that way...