If you want to use a different SIM card to get better coverage, you can "openline" or unlock the device. This is often what users mean by "upgrading" their service: Unlocking ZTE MF65 Modem Guide | PDF - Scribd
However, you can optimize your device's performance, unlock it for other carriers, and ensure you have the latest firmware for the best possible 3G speeds. zte mf65 upgrade to 4g free
: Go to Settings > Device Settings > Update Management (or Software Updates ). Check for Updates : Click the Check or Check Now button. If you want to use a different SIM
: Connect your computer or phone to the MF65 Wi-Fi. Open a browser and go to http://192.168.0.1 . The default password is usually admin . you can optimize your device's performance