I have an iphone 4s bought in the US and I am trying to get it unlocked so that I can use it in Singapore. The person who sold me the phone replaced the sim card slot with a gevy slot. When I insert a singtel sim a message pops up "Only compatible sim cards from a supported carrier maybe used to activate iphone" I restored the phone via itunes and currently stuck with the language selection screen. When I go ahead trying to activate the same message pops up. I do not have the parent sim or att sim which I used when I was in USA. I have another iphone under contract in the US but I bought this from a 3rd party and was not able to get it unlocked via att.If the OP or anyone else guide me as to how to unlock my phone that would be very helpful. PS- can anyone confirm that unlocking does not void my apple care plan.