How to unlock Airtel Huawei E1731 (E173bu-1) Customized Firmware Modem Free?
1. Download Universal Master Code calculator software and firmware upgrade of E1731 (E173Bu-1) dongle from the link which is provided at the end of the article.
2. Now run Universal master code tool and generate unlock code and flash code of your IMEI.
3. Plug your device to your PC / laptop and let it launch the software of modem.
4. Now close the running software / Huawei mobile partner and run firmware update E173Update_11.126.85.00.114_B427.exe.
5. It will find your modem automatically.
6. Click Next and when it ask you for password put flash code which you had generated earlier.
7. After a few seconds your modem will be updated with unlocked firmware.
Now after fully updated your dongle, unplug and plug your modem with another than default sim (other than Airtel SIM) in your computer / laptop. Now your dongle will ask you unlock code / NCK. Put the unlock code as password which you had generated earlier and your Airtel E1731 (E173Bu-1) Huawei data card is unlocked forever.
Update : If above mentioned firmware does not ask for password or unlock code the you download this firmware (Firmware Version is E1731Update_11.126.15.00.00.B416). It will work 100% for you.