Originally Posted by stephen1205
thanks,i heard some phone do not use data plan,they act like standalone gps
If a phone has GPS onboard then the GPS ALONE will not use any of your data plan, it's entirely separate. What "could" use your data plan is if you use an app, such as Google maps which uses GPS to locate where you (the phone) are but downloads the relevant map using your phones data link. As others have said, if you use Google maps you can download pre-determined map tiles before you go.
You can also have an app that has ALL of its maps stored on your phone (usually the SD Card) so that it has no need to use your data plan. Handy if you're not in range of a mobile signal. Also, the GPS signal originates from orbiting satellites and so does not rely on you having a mobile signal at all. It is affected by buildings, being underground, the weather, etc.....