What kind of unlock do you plan to do? Unlock to use with a different carrier or did you just forgot your password?
If you plan on using your phone with a different network, you need to have your phone reprogrammed. Just keep in mind that there is no assurance that it will work. It's not as simple like when you have GSM phones unlocked.
If you just forgot your password, the default code is commonly the last 4 digits of your phone number. If that doesn't work try 1234 or 0000. As a last resort, you can contact your carrier. They can possibly reset your password.