I'm thinking of upgrading to the iPhone 5. I'm on AT&T, but have no idea what their LTE network is like in my area. If it sucks, I'd consider switching to Verizon. Can I do this?: - Upgrade to iPhone 5 on AT&T. - If it sucks, during the 30 day return window, purchase a Verizon iPhone 5 and port my number. - Once the number is safely ported, return AT&T iPhone 5 within 30 day window. Will porting the number cause an ETF? Will my AT&T iPhone 5 become unreturnable if I do this? I know I can return the phone within 30 days, but I don't want to lose my phone number, which I've had since 2004!