ok so what I want to do is buy an iphone off craigslist and I want to add a line to my brothers at&t account. He already has a data plan for his blackberry with 1500 text messages and 900 minutes so what I want to do is sign up for 1400 minutes and 1500 text messages with him. What my question is is when I get my iphone how much more will it cost to activate it, i mean all you do is put in the sim card right? And also the total for like a family plan w/ 1400 minutes and 1500 text messages is like about 129.99 plus the data plan my brother already has. Would that price per month be the same If I got the iphone because all you are really doing is just switching to a different phone right? If someone could help me out with some info that would be great thanks!