Greetings all, I current have an iPhone 4 on contract until Feb. 18th 2012. I have a second line that has an iPhone 3G off contract. Can I use the second line's eligibility to upgrade to the iPhone 4 to the iPhone 4S at a reduced price? So it would look like the following: iPhone 4S on contract until Oct. 2013 iPhone 4 on contract until Feb. 18th 2012. Then put in the first line's MicroSim card to retain the original phone number? I just want to make sure that both lines would retain their original phone numbers. Thank you.