Can I use GPS functions on iPhone 3G without mobile phone subscription?

[swevrywhere]

I'm thinking about buying a used iPhone 3G and not activating it with a wireless plan but simply using it as a GPS device (car navigation, geocaching, etc.). Will I be able to use its GPS capabilities without it being on a live mobile phone network?

If so, anything special I need to do such as jailbreaking and/or unlocking? Is there a way to turn off the phone features while keeping on the GPS features to increase battery life?

Any advice would be welcome. Thanks!

 

[pwb2103]

I've been wondering this too. I grabbed the app OpenMaps which lets you download maps while on wifi and then keep them on your phone for when you don't have wifi. I wanted to use my phone while abroad as basically an ipod touch with gps and cellular data turned off. Somehow I screwed it up though and by turning off cellular data I never managed to get a gps lock.

Anyone know the correct way to do this? Recommend a better maps program than open maps?