I have just bought an Iphone from ebay, it has been used previously on an O2 Ipod Sim, my question is that if I put my standard O2 contract sim into it, will it work? Or do I need to unlock using something like ZiPhone? I am not too worried about the net working, as long as I can send SMS and make calls and so forth. I can always use the Wifi for the internet if needs be as long as I am near a router I assume?
Using experience from AT&T the U.S you can not use a different O2 sim, but it may work. I recommend trying it first, than if it doesn't work you should jailbreak and unlock to firmware 2.0 using Pwnge or Winpwn.