Both the Samsung Galaxy S4 and the S3 are devices that are great and at the same time they are powerful handsets. Many people still own them even with newer handsets coming out. Some people bought locked devices due to the fact that they came with subsidies. However when they want to take them to another carrier they have to be unlocked. Luckily this isn’t difficult as there is a leaked unlock code going around.
If you do want to unlock your handset to take it to another carrier you should first get a new SIM card and then switch the handset off to insert it and back on. You should then go into your dial pad and you can type the unlock code which is *#197328640#. You should then check out the steps below to carry on unlocking the handset.
 UMTS >  Debug Screen >  Phone Control >  Network Lock > Options  Perso SHA256 OFF.
If all has gone well you should now have an unlocked Samsung Galaxy S4 or Note 3 and the code is said to work with many other devices belonging to Samsung.