Owners of the Samsung Galaxy Note 3 who have purchased a locked handset and who want to move to a new carrier will have to unlock their device. However this isn’t as difficult as it once used to be as there is an unlock code going around that allows the handset to be locked easily and quickly.
So if you own a Samsung Galaxy Note 3 and you want to unlock the handset you can follow the guide.
To begin with you will need to get hold of a new SIM card and then put the card into your Samsung Galaxy Note 3. When you have done this you can then restart the device and go to the dial pad. You can then enter *#197328640#.
Next, select  UMTS >  Debug Screen >  Phone Control >  Network Lock > Options  Perso SHA256 OFF. You will need to wait for at least 30 seconds here before selecting Back to enter Main Menu once more. From there, you should see the words “Network Lock”, select  NW Lock NV Data INITIALLIZ. If you have followed the steps you should now have a device that is unlocked and you will be able to use any SIM card.
Some owners of Samsung handsets have said that they have tried out the code on other devices belonging to Samsung and it has unlocked them too.