from my understanding of iphone 4.0, it's possible to disable cellular data completely right? if that's possible, can I use an iPhone without having a data plan from AT&T? I've got 2 "semi-retired" iPhone 3G's since my dad and I both upgraded to 3GS and would like to let my mom and sister use the iPhone 3G's as cellphones. Neither of them are interested in cellular data. Right now, they're using the old iPhone 3G's as glorified ipod touches but it would be nice if they could consolidate devices...