Note: before proceeding with steps below, insert operators sim card that does not work with device. For example if it's locked to operator "A" insert operator's "B" sim

Launch DC-Unlocker client

Detect device by selecting Huawei modems from manufacturers drop down menu list, leave Select model as auto detect (recommended) then click magnifying glass button. If device does not have visible COM ports in device manager then DC-unlocker will enable them automatically during detection

Wait till DC-Unlocker fully detects modem

Open Server tab, enter your username and password that you received after credits purchase. Click "Check login". (you can buy credits here www.dc-unlocker.com/buy).

If DC-Unlocker/Vygis/Rocker/Infinity dongle is connected, only click " Check login "

Note: if you can't login or get error connecting to server after connecting Huawei E3131 to PC, check these settings here

Open Unlocking tab, click “Unlock”

Wait till you see a message that device was unlocked

After you see that device was successfully unlocked, restart it. Now you can use it with any SIM card