It often happens when you get the smartphone you dreamt about and don’t like your mobile operator. It’s good when you can switch between carriers and stay with the one you like the most. However you are often locked to a particular network and can’t just take a decision and start using a different carrier. You need to unlock Samsung Galaxy S4 if you happen to have such a device.
Samsung handsets come with Android OS. You can hack Samsung Galaxy but it won’t be a official unlocking and I can’t say for sure that it will be locked. The S4 model is pretty popular and users who got it from a carrier can take all the limitations by performing unlock Samsung Galaxy S4 steps. For example, if you are locked to T-Mobile you can notice bugs in the networks speeds [they are constantly changing from super-fast to super-slow depending on where you are located].
Let’s imagine you wish to use Galaxy S4 on AT&T. Just unlock and enjoy getting the new provider’s services. It is also handy to have an unlocked smartphone when you decide to resell it at a higher price.
It is extremely easy to unlock Samsung Galaxy S4 device. Let me tell you the exact steps you need to follow to succeed. It should take you no more than 5 minutes to finish all the steps.
NOTE. Backup your phone before you proceed. You are unlocking at your own risk, remember this.
Step 1. You need to dial *#27663368378# from your Galaxy S4 smartphone to get to the debug menu screen.
Step 3. Then choose Debug Screen  from your UMTS menu.
Step 7. Select SHA256_ENABLED_FLAG to see:
MENU NOT EXIST
PRESS BACK KEY
Step 8. Your current command is 116631. Select Menu and “Back” option to see the following message:
SHA256_OFF => Not Change
Step 9. Choose Menu and “Back” once again to return to Network Lock option.
Step 10. Select Menu and “Back” to get back to Phone Control.
Step 11. Press Menu and “Back” and you will return to Debug Screen.
Step 12. Click on Menu and “Back” once again to return to UMTS Main Menu.
Step 14. Choose Restore Back-up  option to automatically reboot your Samsung after the menu / back light up.
You should be now permanently unlocked. Check your status by inserting a new SIM card. If everything is ok you will get no pop-up message about an unlock code. You can still locked if you see such a prompt.
Also if you are interesting in Samsung Galaxy S4 rooting you can follow the link because this hack is available for the new S4 version as well.