What types of iPhones work with Straight Talk?

I wanted to know if an unlocked iPhone in general can be crossed over into Straight Talk. The iPhone 4 and also the iPhone 5 are buy-able through Straight Talk (Wal-Mart) but would an iPhone 3G work as well? Anything helps.

I'm not sure about straight talk but there's a new company called Solavei. They run on the T-Mobile network so they have good reliable service.

49/mo no contract. No credit check.

Unlimited voice, txt and 4g data.

Your iphone should work. If you go to solavei.com/teamapex and check coverage and your phone it will tell you if your phone is compatible with their service. Don't forget to sign my guest book. ; )

Yes, I have read that this will work. Sources below.