How to activate a Viettel Gift Card key?

Activating a Viettel Gift Card key is really simple, just follow these steps:

1. Activate Your Viettel Account: Ensure your mobile account is active and you have a valid Viettel SIM card inserted. 
2. *Dial 100#: From your Viettel mobile phone, dial *100# and press the call button. 
3. Enter the Code: The system will prompt you to enter the Viettel code. Carefully enter the code provided on your gift card. 
4. Confirm and Recharge: Press the call button to confirm and complete the recharge process. 

The key is not working

If you have activated the key according to the guide but the code appears not to work, please check what type of error message you receive and depending on it follow the appropriate instructions:

• My key is Duplicated / Already Used. How can I proceed?
• My key is Invalid. How can I proceed?
• My key is region locked / can't be activated in my country. How can I proceed?
• My key activated a different product that it was supposed to. How can I proceed?
• The key I bought didn’t activate all of the content it was supposed to. What can I do?