I have a line with ATT right now for my iphone (1 year left on contract) and I want to take this number and use it for a new phone on Verizon. Do I have to cancel my ATT contract in order to do that? I already have a Verizon account (one line on a family plan) and ideally, I would just switch numbers (Verizon number is moved to ATT and vice versa). Can I do this without canceling any contracts (i.e. keep my unlimited data plan with ATT & NOT pay ETF)? THanks!