You must use Microsoft Azure. I created an account, but I cannot log in with MFA. The security code does not appear on my mobile device.

Dear 황준성, 

Good day! Thank you for posting to Microsoft Community. We are happy to help you!   

I'm sorry to hear you're having trouble with your Microsoft work account due to with two-factor authentication. 

First, please give an attempt for Change how you do additional verification. 

If can't work, as your query is related with Authenticator app, we do have separate community team, so, it is recommended to post via Microsoft Authenticator - Microsoft Q&A, so that a support agent from this team can check and provide you required information. At this moment, your kind cooperation and understanding will be highly appreciated. 

Also, could you please tell us is there any other global administrator in your organization?  

If so, please be kindly to contact him/her to give an attempt for - Set up multifactor authentication. 

But if you are the only admin and cannot access your account due to an authentication issue, it is suggested to contact the Data Protection team as we are from the community team and are not authorized to reset any user/admin accounts. The data protection team is the only support team to verify and reset the account. To find the Data Protection team's contact number, see Find Microsoft 365 for business support phone numbers by country or region - Microsoft 365 admin | Microsoft Learn. (Please understand that we do not have the authorities for operating on the backends.) 

Depending on your country or region. For some countries, when calling the support number, although there are about 30 seconds opening as something "you can visit the link...." But you can ignore this opening and wait until the option, then "1" as a business email user, "1" again for technical help. 

For some countries, it will be an automated conversation like: First, when you call the hotline, it asks what kind of problem you are worried about. 

Answered: authenticator. 

A: What kind of product are you using? 

B: Office 365 for business. 

A confirmation: education or company account? 

B: For companies 

A: Are you an administrator? 

B: Yes. 

A: Do you have the other admin in your organization? 

B: No. 

A: You need one.... Service request? 

Thanks in advance for your understanding! 

Greatly Appreciate again for your patience and understanding. 

Sincerely,   

Thu-D/Microsoft Community Support Specialist

"Last updated: January 6, 2019

Depending on how your Microsoft 365 admin set up multi-factor authentication (MFA) for your organization, you might be able to change how you so your secondary verification. **Tip:**Before you can do these steps, your admin needs to set up MFA for your account.

The steps below are for accounts you use with Microsoft 365 in your work or school. If you're trying to set up MFA for a personal Microsoft account see How to use MFA with your Microsoft account.

1. Sign in to Microsoft 365 using your password and second verification method.
2. Click here to see the Additional security verification page.
3. Choose how you want to do your second verification. Although all options are listed, your admin may not make them all available; you'll get a message if you choose an option your admin didn't enable.
4. When complete, click Save."

Even when I try to proceed with the above steps, I am asked to enter the mobile Outlook security code. However, the mobile Outlook security code does not appear. I have uninstalled and reinstalled the app, and tried it on other phones, but the problem persists.

The only way to log in is by entering the Outlook security code, so I am unable to resolve the issue.

Dear 황준성님, 

Thank you for your detailed follow-up.  

Based on your description, it seems that: 

You are being asked for a security code from Outlook, but Outlook is not the correct app to receive MFA codes. 

Normally, MFA codes are sent via the Microsoft Authenticator app, SMS, or phone call, depending on how your admin configured it. 

What You Can Try 

Check if Microsoft Authenticator is installed 

Make sure you are using the Microsoft Authenticator app, not Outlook, to receive the code. 

If you previously set up MFA with Authenticator, open the app and check for pending approvals or codes. 

Try signing in from a browser 

Go to https://portal.azure.com 

Use your university account and see if it prompts for another method (SMS, call, etc.) 

If you are the only admin and cannot access MFA 

You will need to contact the Microsoft Data Protection Team to verify your identity and reset MFA. 

Please follow this link to find the support number for your country: Customer service phone numbers - Microsoft Support 
When calling, choose:
“1” for business email → “1” for technical help → then follow the prompts.

Best regards,

Thu-D/Microsoft Community Support Specialist