How to unlock a iphone 4 with a bad esn s carrier?

I have iphone 4 that is for verizon and has a bad esn. How do i unlock it so i can use it for at&t, that requires no jailbreaking or anything difficult? Someone help me please.

Can't, verizon is a cdma and att is a gsm network.
it won't work.
trade it for a att iphone… Email me if your in PA