I was just looking around on whether is there a simple or easy way to unlock Samsung Galaxy S3 and you know what I found a very simple way to accomplish this. This is yet to be confirmed by myself to work on AT&T Galaxy S3 and it is reported to work on ALL VARIANTS of GSM.
Please do not profit off this…..as this is completely free.
To unlock your Galaxy S3 OR Galaxy NOTE 2:
- Just dial the following keys on your phone dial pad *#197328640#
- Your will now see Main Menu.
- Select  UMTS
- Select  Debug Screen
- Select  Phone Control
- Select  Network Lock
- Select Perso SHA256 OFF
- After choosing this option, wait about 30 seconds
- Then go back one step by pressing the Menu button (left button to Home button) then select Back
- Now you should be on  Network Lock screen
- Select  NW Lock NV Data INITIALLIZ and wait for a minute
- Reboot your phone
*Standard Disclaimer: I am not responsible if you don’t follow directions and what you do with your phone…
Please share this if it works for you…