So I'm going to be doing the Best Buy tradein for my 3GS and since that takes up to 14 days I don't want to be completely without a phone for 2 weeks. I have an old first gen iPhone sitting around that I was planning on using. I was wondering if I could just put my 3GS SIM into the 2G and have it work fine and retain my current $30 unlimited data plan that I have with AT&T? I've switched the SIM but when it connects to iTunes it wants me to verify my account and before I go any further I want to make sure that they won't change my data plan on me or try to set it up as a new line or anything. Any help is greatly appreciated. Thanks.