I'm trying my very hardest to move my mom away from her old flip phone, so I gave her my old iPhone 3GS. Thus far, she's just been using it as an iPod touch. I'm trying to convince her to use it as a phone, but she's worried that she'll wind up being charged for data. So I'm thinking that if I turn off the Cellular Data switch in the networking settings, this won't happen. Can someone confirm this, or tell me otherwise? Ultimately, I guess what I'm worried would happen is that AT&T would somehow figure out her SIM has been placed in an iPhone, and start tacking on charges for no legitimate reason. Anyone got experience with this, and would like to share what would happen?