For 95% of users, buying a remote unlock code from a reputable online service is the best option. Prices for the MF920V usually range from $10 to $25.
Unlocking is not the same as rooting or jailbreaking. It does not void your warranty in most regions (including the EU and USA), and it does not modify the device’s firmware. It simply removes a network filter. unlock zte mf920v
If the software above fails, it means your firmware is patched. You may need to downgrade the firmware or flash a generic "unbranded" firmware. For 95% of users, buying a remote unlock