Originally Posted by frahse
I don't doubt that some phones have a complete GPS chip and system, but many have "aGPS" which is "assisted GPS" which works off the location of cell towers. There can be errors tied to where you are in relation to the towers and how far away the towers are.
There are also various levels of GPS chips with variations on sensitivity and number of satellites used.
You are correct that AGPS is assisted GPS, but it is actually an enhancement. It possesses full GPS capabilities, and supplements that using cellular towers, as well as the cellular data plan. This allows it to get locations in places traditional GPS will not, such as indoors or under tree cover. AGPS is GPS that has been enhanced, not a substandard substitute.