Any way we can convince you to pass that handly little unlock code on to us? =)
Of course Provider unlock codes are specific to devices, but it's not too difficult to get the code for your own phone. Call your Provider/Carrier and tell them that you are going to be taking your phone overseas..... (after all, that's why we buy a "world phone" isn't it?)
If they don't already have it, they will need your IMEI number..... remove the battery and you'll see it on the small label on the phone.
You may be given the number then, or receive it via email. Once you have the code, you will need to insert a SIM from a carrier other than your current one. When you power up you'll be prompted for the code. (Enter code carefully, 5 mistakes and the phone is permanently locked.)