im on AT&T and my gf is on Verizon with her family. she has 3 upgrades available so can essentially get 3 iphone 4s for new contract price. I am not eligible for upgrade on AT&T. my question is since this is now a world phone can I get her to get me an iphone 4s with her Verizon upgrade and throw in my AT&T sim card off my iphone 4? saving my upgrade for iphone 5 in the process plus $200+