Stated another way, none of the iPhones purchased with the default providers (Rogers, Telus, Fido, etc) will work with a SIM in Argentina - you need an unlocked phone purchased from the Apple store directly, or to unlock it using third-party software. That said, if your contract is up on your phone you may be able to pay the provider to unlock the phone for you (I think Telus will unlock it now for $50).