All of the guides I've seen seem to be the "box to unlock" methods. I have an iPhone that's already been activated with AT&T plan. I want to unlock it now because I do plan to travel outside of the U.S. At first, I was hoping to use the "Iphonegoboom ..." [possible typo] to restore mine back to virgin, but many confirm that this doesn't really work. Any suggestions? Thanks in advance!