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
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 E5170 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 by disconnecting and connecting back. Now you can use it with any SIM card