First of all use this code *#06# to know 15 digit IMEI number of your mobile phone which is used to get nokia unlock codes. You can find site which provide free nokia unlock codes. I know one blog which guide you for nokia unlocking for free.

First find IMEI number of your mobile phone. That will help you to get nokia unlock codes.
This can be done
     by either removing the back of your cell phone and looking underneath the
     battery, or simply by typing in *#06# into your cell phone. It should be
     something.