Anyone who owns the Samsung Galaxy S3 unlocked version or the Samsung Galaxy Note 2 are now able to unlock the device and it doesn’t cost a penny. When you unlock the phone you are able to use it with any carrier you want and use it around the world.
For instance if you have the AT&T version of the Samsung Galaxy S3 then you can only use it with the network, however when you unlock it, it can be used with any or even be sent overseas. So to unlock your device follow the steps below.
Insert a SIM into your Note 2 or Galaxy S3 that ISN’T from your regular carrier. Switch the handset off and on again, with the new SIM inserted.
Go into your dialpad and key in *#197328640#. Head to Main Menu >  UMTS >  Debug Screen >  Phone Control >  Network Lock > Options  Perso SHA256 OFF. Then wait for around 30 seconds. After this, go to Menus and select Back. You should hopefully see Network Lock. Choose  NW Lock NV Data INITIALLIZ.
Just to be sure you didn’t make a mistake, the sequence you need to type in is: Asterisk Pound One Nine Seven Three Two Eight Six Four Zero Pound. Some people call the asterisk the star button, and the pound button sometimes gets called hash.
Your Samsung Galaxy S3 or Galaxy Note should now be unlocked and you will be able to use it with any carrier around the world. Samsung have used this code in the past on their handsets for quite some time so you might want to try other devices belonging to Samsung.