PLEASE PLEASE PLEASE can someone help.

I recently returned my iphone to the states for warranty repair. it was replaced with a brand new one which was posted back to me in the uk with version 1.1.1 installed. Brand new and an American phone.

I received it here..........did not connect to itunes..........put my orange sim inside and then used appsnapp and anysim to unlock it.........

The phone works perfectly just one problem, ...............when i connect to itunes , it says ....."there is no carrier that accepts my sim, please insert a valid sim card"

Subsequently I cannot sync my iphone.......so cannot sync contacts or music onto the phone. I can manually drag music onto it but cannot take it off............

I have tried different versions of itunes but no joy...............

Please can someone help me ??????