Ia m thinking of purchasing an unlocked 5s or 5c in the US to take back to New Zealand to use with a local GSM carrier (Vodafone or 2degrees). Will there be any issues using the iPhone in NZ? Will the iphone be compatible with NZ's data network and frequencies they work with. In NZ we use a GSM based system. Does anyone have any experience with using an unlocked US iPhone in NZ?