I am looking to use a upgrade from another line on my mother's family plan. I had a iPhone 4 that I just sold off and I am planning on getting the S3 once it is released. The line I am looking to use currently has a dumb phone on it, never had a smart phone/data package. Will this effect anything when I use that line to upgrade? Like forcing a data package on that line for example. Also how does the extentsion work. Is the line I am using to upgrade get locked in for 2 years or does mine?
When you upgrade that line with a smartphone it will require a data package be put on the line. Once you get the phone you can call in and have the new phone activated on your line and have the data package removed from the other line.
Regardless of where the phone is used, the line that is upgraded in AT&T's system will get a new 2 year contract.