Hello My friend purchased his iPhone 4 from abroad, where he was able to use it without any problems. Granted, he was using a turbo SIM and had to turn on and off airplane mode each time the phone booted but aside from that it was fine. He's in the UK now and we've tried to upgrade the software to iOS5. It installed fine but it refuses it activate. The following appears both on the iPhone and on iTunes: "The SIM card inserted in this iPhone does not appear to be supported. Only compatible SIM cards from a supported Carrier may be used to activate iPhone. Please insert the SIM card that came with your iPhone or visit a supported carrier's store to receive a replacement SIM card." So, clearly the phone is barred and that is why it is refusing to work with various SIM cards. Does anyone have any suggestions? Can we downgrade back to iOS4? Or is there a way to activate the device without a SIM card? Thanks in advance!