well cant be fully unlocked (unless you call your service provider to get your code) but you should be able to patch it which keeps it unlocked but it be locked again if you flash it or upgrade the software.etc
heres the steps:
once flashed or debranded.
use setools lite 1.10.
use qamaker (found in the setools lite 1.10 folder) to make ur quick acess vkp file (using your main)
use simlock patch generator (download seperately) creates vkp file (using your main)
*note the main is the one you used to flash the phone.
then use selite tools:
mark bypass db2020
click "ADD" (big button), your main
click "..." (in misc line), your vkp file made from qamaker.
flash
press NO at the end...
reopen the file selite tools (or clear the stuff e.g. untick the bypass db2020 .etc)
so now tick use quick acess below bypass db2020
click "...." your simlock patch vkp file generated.
click write script
press no at the end...
finish please do not pull out cable or you have a chance of bricking and battery is full :)
MAKE A BACKUP OF YOUR GDFS FILE ASWELL!
(via XS++ or SEtools lite 1.10 incase anything goes wrong e.g. power cut LOL)