Hướng dẫn unlock sim free galaxy s4

Here are the steps:
Goto phone dailer, and enter *#27663368378# for the debug service menu.
In "ServiceMode", select [1] UMTS
In "UMTS MAIN MENU", select [1] DEBUG SCREEN
In "DEBUG SCREEN", select [6] PHONE CONTROL
In "PHONE CONTROL", select [6] NETWORK LOCK
In "NETWORK LOCK", select [3] PERSO SHA256 OFF
It should show:
SHA256_ENABLED_FLAG[1]
SHA256_OFF => SHA256_ON
Now touch the first line SHA256_ENABLED_FLAG[1]
It should show:
MENU NOT EXIST
PRESS BACK KEY
Current Command is 116631
Now press the menu button and select "Back"
It should show:
SHA256_ENABLED_FLAG[0]
SHA256_OFF => Not Change
Again, press the menu button and select "Back", and you're back in the "NETWORK LOCK" screen
Press the menu button and select "Back", and you're in the "PHONE CONTROL" screen
Press the menu button and select "Back", and you're in the "DEBUG SCREEN" screen
Finally, press the menu button and select "Back", and you're back in the "UMTS MAIN MENU" screen
Select [6] COMMON
In "COMMON" screen, select [6] NV REBUILD
Now you are in the "NV REBUILD" screen, you should see the following text:
------------------------------
Golden-Backup exist
You can Restore Cal/NV
------------------------------
Now for the final step.
In "NV REBUILD" screen, select [4] Restore Back-up
The button lights for menu and back should come on, and the phone will auto reboot in a few seconds.
xong phim ^_^