Apple ipod

Unlock 3G iPhone OS 3.1.3?

Hi Guy here is my problem, I have a Vodafone 3G iPhone in the United Kingdom in the contract and instant messaging currently in New Zealand, the iPhone is SIM-locked and version 3.1.3, I heard that you can not unlock the SIM lock on jailbreak you can not, however, my question is, what I can get this SIM card to unlock O2 or Vodafone? because I'm not looking for jailbreaking but I just get rid of the lock SIM correctly (legitimate), but I had the SIM unlocked, it'll open again after an update to the iPhone? for example, OS 4.0 Thanks

just ask the unlock code here: http://www.unlock-direct.com/index.php

Downgrade 4.0 to 3.1.3 iPhone OS 4.0を3.1.3にダウングレード