Adding a line to AT&T ????

They have a family plan so each additional line cost $10. For example my mom and her bf has a family plan. They pay about $85/month for their 2 lines. My mom added me in and so she would be paying about $95/month. But since I got the iPhone and all the additional features like unlimited texting and websurfing, it ended up being $60 more. So, if you want extra stuff, then it'll cost more. But for your line alone, it's only $10.