Okay, so I am currently on a 3 person family plan, with no data. I just bought an iPhone 4 and want to use it, we have been on a 2 year contract for a year now, and I want to add a data plan. How much will it cost to swap phones? Will I have to pay to swap phones? I know I'll have to pay the extra $20 a month for data, but I'm not sure if they charge for phone swaps. Thanks!