Do not download from random pop-up sites. Use these reputable sources:
Unlock firmware restores the "SMS" tab. You can set up SMS to email, which is vital if you use a prepaid SIM that needs top-up alerts. huawei b311s-220 unlock firmware
There are two primary ways to unlock this device. The method you choose depends on the current software version of your router. Do not download from random pop-up sites