Need to have a second phone, I have an individual plan with the iPhone 3G now. Wondering if I can buy another iPhone 3G, get a family plan, then sell the new iPhone and just use an older extra AT&T phone I have for the second phone line. I'd net about $300 ($600 on ebay minus $300 initial cost). Would I still have to continue paying the second $30 data plan for two years or would I be able to cancel that? If not, that would wipe out any advantage of selling the iPhone for about $600 on ebay. Thanks!