for AT&T the Data Plan cost 30$ but what does the data plan allow you to do on the iphone? i think internet guessing but is it free web then? Thx

internet is pretty much what Data is, yeah.

I'm on about a 480 min plan + unlimited texts its about 108$/month with AT&T

so if you add another fone / line to contract, with same, unlimited text + data. how much you think that would be?
i want iphone as well

A line is only like 9.99 more, but obviously you can't really share 480 minutes a month between two people? Hope not lol.

An alright family plan is like 150 or something?