I have a prepaid go phone for att, but i want to buy an jailbroken iphone?

I have a prepaid go phone for att, but i want to buy an jailbroken iphone. Now can i put the sim card thats in my prepaid phone in the jailbroken iphone and have service through att. And will it still be prepaid with no contract? Help me out please. And give me some details on how to do that. Please help me?

Added (1). I have a smart phone through att. But its a go phone. So can i just put my sim card in the iphone and itll be a go phone iphone?

You will need a data plan, att will add one to your bill as soon as they detect a smartphone.

Yes, you can do that. But, data on an AT&T prepaid plan is very expensive.

First of all a jailbroken iphone won't do anything, you need an unlocked one! Secondly, yes you will have to put a data plan (internet) on it, and depending on where you go, some AT&T reps won't let you even activate the iphone on a prepaid. The thing is, the prepaid sim that comes with the go phones do not work in a iphone, they are locked to those specific go phone devices, you will need a new sim card which some places might charge $25