On my moms 2yr old iPhone 3G I downgraded it to 3.1.3, put my SIM in and turned cellular data off. It was working fine on my unlimited call and text plan. My dad accidentally sent me a picture and it said I used data, not charging my plan. I download the Fake APN thing and data was basically double blocked. Today AT&T sent me a text saying my plan isn't right and they are adding a data plan. My dad was on the phone with them and they blocked my data again and set my phone to my old one. I've been using the phone since Jan 20 something and they found data on Feb 8 and got mad on Feb 9.

Any way I can unlock it or hide my serial number or something so that it would work?