My wife is going to Europe and she wants to bring her iPhone (which she uses with a GoPhone plan), so she can use all the features and apps allowed thru wi-fi while over there. She knows she won't have access to voice, text or data thru the cellular signal (She wouldn't want it if roaming were offered for GoPhone there anyway).

Can she just turn her phone on over there and use it almost like an iPod touch only?
Will the phone at least register to a local GSM provider (even if no voice/text/data service can be used)?

Since there is no option to turn temporarily only the cellular signal off (airplane mode will turn wi-fi off too), my concern is that the phone will keep "searching..." for an at&t signal and drain the battery very quickly. Also, not having to remove the GoPhone SIM from the iPhone would be a plus.

Thanks