Happy Tinkering!
Here is everything you need to know about unlocking the ZTE MF286C via firmware modification. Most phones use a 16-digit NCK code to unlock. The MF286C is different. These units often ignore generic unlock codes or require complicated DC-Unlocker credits. The most permanent, reliable method for the MF286C is a firmware flash . zte mf286c unlock firmware
You will need Balong Flash (for the modem) and SP Flash Tool (for the main CPU), depending on the exploit. Happy Tinkering