This is the safest method and does not require "flashing" risky third-party firmware.
2. Using Unlock Software (DC-Unlocker/Huawei Modem Unlocker) huawei b311s-220 unlock firmware
If you do not have an unlock code, you can use software tools to read the device information and calculate a code or apply a direct unlock. This is the safest method and does not
