I currently have Sprint service (Im a college student, my bill is payed for me, unlimited everything with great coverage and speeds, so no unecessary bashing lol). Im not due for an upgrade on my line until May, hopefully right in time for the iPhone 5. I want the 4s now though, im tired of my EVO 4G. My mom has a full upgrade on her line that she will let me use to get a phone. Will we be able to purchase a 4s with the discounts and contract extension on her line, and simply change the numbers? Thanks.