so i got an iPhone 2g from a friend. I want to get goPhone service on it. so i bought a GoPhone from walmart. I activsated that phone then once the iPhone was unlocked/Jailbroken on 3.1 I popped in my sim card and it jjust says No Serivce... How do i make it work? even if i do have to downgradee to like 3.0 or anything?