HELP! If I added a line to get the iPhone 5, how do switch it to my primary line?

I'm on AT&T and added a line to a family plan to order the iPhone 5.

I want to put that added line on a dumb phone and switch the iPhone 5 to my primary line.

How would I go about doing this? Who do I call and what are the steps?

Also will AT&T give me a hard time about subsidizing a smartphone and immediately switching it to a dumb phone?