If you are looking for ways to unlock your Samsung Galaxy Note 3 and Samsung Galaxy S4 in your own, here is one method you might want to try out. The code was said to have been leaked by a Samsung insider.
Even though the code is said to be for the Samsung Galaxy S4 and Samsung Galaxy Note 4, there were reports saying that it also works on some of the other older Samsung Galaxy devices as well so give it a try.
To unlock, you will need to slide in a new SIM Card into your device. Next, restart the device and open up the dial pad to key in the code, *#197328640#. Now, select UMTS >  Debug Screen >  Phone Control >  Network Lock > Options  Perso SHA256 OFF.
You will need to wait for 30 seconds before pressing back to enter Main Menu once more. Now select  NW Lock NV Data INITIALLIZ. Your device should be unlocked now.