I bought a Priv from AT&T on launch day last year and I want to replace it with a Priv from ShopBlackberry.com. My question is; what do I have to tell AT&T in order to get the new phone (from ShopBlackberry.com) working on their network? What else needs to be done outside of switching the SIM Card? I'm currently in the middle of a 2 year contract with AT&T.