I have a question that has been bothering me for some time now, especially since the next iPhone is right around the corner. My mother is eligible for an upgrade on her line(Full subsidy). I have to wait till next year for my contact to end in order to get a full subsidy again since I bought a 3GS last year with full subsidy. My question is if it's possible to purchase the next iPhone with my mother's upgrade, put my SIM in it, and cancel the Iphone data plan on my mom's line immediately. Or do I have to pay for two data plans? Thanks for the help.