Error Code: 399287 when using mfa

Hello @JOS KLEVER,

Thank you for posting your question in the Microsoft Q&A forum.    

We understand you are currently unable to access your administrator account due to issues with the Microsoft Authenticator app. Additionally, the error code 399287 encountered when using the SMS method indicates that the account has been flagged with a reputation concern.

Could you please confirm if there is another Global Administrator in your tenant? If so, they can assist by resetting your MFA settings through the Microsoft Entra admin center. This involves revoking the current MFA session and "require re-register your authentication methods" (Manage authentication methods for Microsoft Entra multifactor authentication) 

Otherwise, our Data Protection team can support you in this matter by using established tools and processes to verify your identity and help restore secure access to your administrator account.

Please note that forum moderators have no control over user accounts, especially when it comes to logging in to your account, resetting your password, changing your access, etc.      

Therefore, please try to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support   

Here are some tips and an example of a prompt to help you navigate the IVR more effectively:  

(When you call the support number, you may hear an introduction of about 30 seconds such as "you can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.)    

In some regions, the initial interaction may be automated, so here’s a general idea of how the conversation might go to help you prepare:      

What kind of problem are you experiencing?         

Answer: Authenticator         

What products do you use?         

Answer: Office 365 for business         

Is this for an education or company account?         

Answer: For companies         

Are you an administrator?         

Answer: Yes         

Are there any other administrators in your organization?         

Answer: No. I am the only admin in my tenant          

Do you need a... Service request?          

Answer: Yes. I need to create a ticket. Please send me direct to the Data Protection Teams.      

I hope this information helps you take the right steps to regain access to your account. If you have any updates or additional

If your organization's Office 365 Business/Education subscription is from a partner or reseller, and the global administrator is unable to open a service request on your end, contact the reseller's support provider to help open a service request on behalf of you instead.   

I hope this information helps you take the right steps to regain access to your account. If you have any updates or additional details, please feel free to leave a comment under this post. I’ll be happy to assist further within my scope.   

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