I have a jb and unlocked 3gs which has been activated{hacktivated??) through I tunes. It is a UK phone and the carrier is locked to O2, which I have confirmed via the Apple site. Is it possible for me to put an O2 pay as u go sim card in the phone and use that sim instead if I want to or will it try to activate again and reject it. Does it matter which sim card is in and does i tunes/apple know what the phone number on the sim is.Obviously at present I dont want to upgrade from 3.0.1 to 3.1 or I will lose the unlock. If however I did do that could I just continue by using the O2 sim that I had when the phone was purchased. Thanks guys.