Factory SIM unlock code of ZTE S521 is available, means permanent unlocking of ZTE S521 is possible using a correct NCK code. We can unlock all ZTE easily by IMEI. There is no need to change the firmware to unlock it, if the phone prompts for unlocking code after changing the SIM card. Unlocking of ZTE S521 by code is recommended method as you will not loose the warranty of the phone. It is the fastest and secured method to unlock the phone by IMEI code. Unlocked phones can be used with all networks SIM card around the world.
To unlock a ZTE phone, we need only 15-digits IMEI. You can find the 15-digit correct IMEI by dialing *#06# on the phone.
The unlocking of the ZTE S521 by code is a recommended method by the manufacturer. Since the unlock code comes from manufacturer database, it will unlock your phone 100%.