Originally Posted by 1phantom
no idea mate
Did it come with an application called Cydia?
Try restoring your phone again and see how you get on. If not, you may have to get down to your local o2 store and get an iPhone pay as you go sim card. You will have to port your current number over to the new sim card (takes a few hours) but you will be fine.
I can't remember off the top of my head the price of the sim cards, they aren't expensive. Before you buy, have a word with the o2 staff, I can't understand why your sim wont work. Just try another restore and see what happens.