changing plans with at&t

[BEASTMAN]

Hello everyone, I am with sprint so I am not aware of how att works with their plans. I am wondering if there is a fee or a contract extension if I were to change my plan later. Lets say I get the basic iphone plan. Later I want to upgrade to the 900min and 1500 text messages, is that possible by just giving them a call and nothing changes besides the plan? Also what time does their nights and weekends run?

 

[qzak]

you can just log on to their website and change your plan instantly, add additional features to the plan, etc.