Steps to follow to free the terminal

Open the phone bookmark on your Galaxy S4 and dial: * # 0011 #
Press the Menu button and then Back or "Back" in the drop-down list. Then press the Menu button again and select Key Entry. Type 1 and press OK to enter Service Mode.1
Press Menu again and press Back again. The Service Mode main menu is then displayed. Click on the option [1] UMTS.22
Now select [1] DEBUG SCREEN, and then press [6] PHONE CONTROL.3
On the close screen, choose [6] NETWORK LOCK.4
In the next menu, there will be three options. Click on [3] PERSO SHA256 OFF.5
Now you have to go back to the main menu. To do this, press the Menu key and then Back or "Back" in the drop-down list. In the main menu [6] COMMON, and then [6] NV REBUILD.6
The phone is informed that there is a backup. Now, press [4] Restore Backup.7
At this point, your phone will first be blocked. It will then restart automatically, showing the black screen and the Blue LED and the buttons on the Capacitive Menu and Back buttons on. This may take a couple of minutes, take it easy.
Once it is turned on again it connects to the mobile network of your telephone company and is permanently released. To enjoy

Now the Samsung Galaxy S4 can be released and can be used by any SIM card from any phone company. Remember that this method is quite recent, so it may not work with some terminals.