Can I have a prepaid iPhone 4?

So I have a prepaid At&t Go Phone. I have the $50 plan (unlimited talk & text, no internet unless I have Wi-Fi). I'm planning on getting an iPhone 4 in about 2 months. Is it possible to have the phone & keep my prepaid plan?

If you want to keep the perpaid plan you best off buying a iphone from from At&t or ebay if you go with At&t be sure it a gsm phone and check and see if you can used your own phone on At&t other phone service will let you check walmart there are plans you like