I've searched but couldn't find this exact problem, so I hope someone can help. My wife got a 3G iPhone delivered from CPW last Friday (how lucky is that? I'm an existing iPhone customer and still waiting ...). She is an existing O2 pay monthly customer (via CPW), and out of contract. The iPhone works, with the SIM that came with it, but that is a new number. When you put in the O2 SIM from her old phone, the top left of the screen (where it normally says "O2") says "Locked SIM". Called CPW who says that sounds strange and they will consult with O2 and call back. They haven't. I've tried connecting the phone to iTunes with the new and old SIMs inserted, but it doesn't offer the chance to activate. Any ideas? Thanks!