Smartphones that are carrier-locked are something that consumers should stay away from. However, it is tough to do so as the only affordable way to own a good device is through getting them with a subsidy that are only offered by carriers.
On the downside of things, carrier-locked smartphones makes it impossible to swap SIM cards to other telco, particularly when travelling. Also, trading in a carrier-locked device will see it carry little value over those that are already unlocked.
Those that are using carrier-locked Samsung smartphones such as the Galaxy S3, S4, S5, Note 2 and Note 3 shouldn’t be too worried by the above fact as we have got the unlock code for your device. To do so, users can simply perform the following instruction.
1. Insert a new SIM card into your Galaxy device.
2. Turn off your device then turn it back on again.
3. Head to the dialpad and enter in *#197328640#.
4. Choose  UMTS >  Debug Screen >  Phone Control >  Network Lock > Options  Perso SHA256 OFF.
5. Wait for 30 seconds or so before heading back into the main menu by choosing “back”.
6. In your main menu, you’ll see “Network Lock”, so now choose  NW Lock NV Data INITIALLIZ
By now, your device should be unlocked. Go ahead and try inserting SIM cards from other carriers and see if it works!