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Error Code: 399287

Daniël Mol 35 Reputation points
2025-08-08T21:55:28.6366667+00:00

Unable to Verify Identity for Azure Login – Error 399287

I can successfully sign in to my WORK Microsoft account, but then, I'm prompted to verify my identity. However, when I do SMS verification, I receive the following error message:

Error Code: 399287

Request Id: removed PII

Correlation Id: removed PII

Timestamp: 2025-08-08T21:29:51Z

I'm aware that this is a known problem with SMS, and "bad reputation" for phone number.

And no other options for MFA is offered.

I have already tried alternative login methods and password reset options but have been unable to complete the identity verification process. I would appreciate your assistance in resolving this issue as soon as possible. Please let me know if any additional information is required.

I can send necessary information (tenant id, etc) of my WORK Microsoft account to remove this "bad reputation".

Thank you for your support.

Microsoft 365 and Office | Other

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  1. Daniël Mol 35 Reputation points
    2025-09-01T15:20:20.1866667+00:00

    I had contact with Microsoft 365 Data Protection support and they help my with the MFA problem. Because SMS verification is not working well anymore.

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  1. Ian-T 7,630 Reputation points Microsoft External Staff Moderator
    2025-08-19T16:00:47.5933333+00:00

    Hi Daniël Mol

    It has been a while and I am writing to see how things are going with this issue.  

    Have you had a chance to check the replies provided?  

    Any update would be appreciated. 

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  2. Ian-T 7,630 Reputation points Microsoft External Staff Moderator
    2025-08-11T00:25:26.94+00:00

    Hi Daniël Mol

    Is there any update on this thread?  

    If the issue has been resolved, please mark the helpful replies as answers.  

    This helps others in the community facing similar problems.  

    Thanks for your understanding. 

  3. Tahreem Saleem 0 Reputation points
    2025-08-09T03:19:43.41+00:00

    Error 399287 means Azure has blocked your phone number for SMS verification due to a “bad reputation” flag.

    You’ll need your IT admin (or Microsoft Support) to reset your MFA and unblock the number.

    Once fixed, use Microsoft Authenticator instead of SMS for future logins.

  4. Ian-T 7,630 Reputation points Microsoft External Staff Moderator
    2025-08-09T02:15:00.5433333+00:00

    Hello Daniël Mol

    Welcome To Microsoft Q&A Forum.

    I understand that you are encountering Azure login error 399287, which typically occurs when the phone number used for multi-factor authentication (MFA) has been flagged by Microsoft's PhoneReputation service due to a "bad reputation" or suspicious activity. This results in SMS or phone call verification being blocked—even if the number works for other Microsoft services

    Since your email is a business account, your company IT team or Helpdesk may be able to reset your Multi-Factor Authentication (MFA) settings. This will allow you to reconfigure MFA from scratch on your new device.  As we are forum moderators, we do not have administrative access to change these settings. Only your IT team has the ability to adjust or reset your MFA configuration. You can also refer to this Microsoft support article for more information: Manage authentication methods - Microsoft Entra ID | Microsoft Learn

    If you cannot reset your MFA, please kindly follow these steps:

    1.Set up a Temporary Microsoft 365 tenant using trial license: Microsoft 365 Business Plans and Pricing

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    2. Raise support ticket

    • Once you have created and registered a free trial, please visit Microsoft 365 Admin Center and click " Help & Support " to raise your ticket.

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    3.Contact via phone number to Microsoft Support:

    These are the recommended options that you can kindly follow to help resolve your issue

    Please feel free to let me know if you need any further assistance.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".  

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

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