If you have a provider-branded device (e.g., German Telekom or Optus), certain menu options may be hidden. Changing to a global firmware is difficult and usually requires advanced hacking tools or community scripts from sites like Update Not Found? If the router won't find a new version, go to Applications System Update Delete Data to clear the cache before checking again. Backup First:
Verdict: Only attempt this if you are an advanced user with a USB-to-UART debug cable. Zte Mu5001 Firmware
This is where the comes into play.