I have a 3g iphone but do not have the original sim card.
The phone has never been jailbroken or unlocked - it originally came with a TurboSim (which did work with a Vodafone sim) but it's now broken.
If I put a sim from a fully legal 3g phone in it and plug it into itunes it tells me an invalid sim is inserted and won't let me access the iphone gui.
All this means I can't access the restore screen in itunes to start the jailbreak process and then go on to unlock it.
Any bright ideas..?