My brother has a Blackberry Curve and we are getting an iPhone 3G from a friend. He wants to know if he can take his SIM out of the blackberry and stick it into the iPhone and be able to use the phone and texting, etc. From what I understand, the data will not work because it is on a 'BlackBerry Data Plan' and he would need to get onto an 'iPhone Data Plan.' We don't want any additional charges, hell we don't even want AT&T to know we are using this phone. Will this work?