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Cannot login to Microsoft 365 account due to error Mobile Number Bad reputation (Error Code: 399287)

Nutthawut Tangudomsiri 25 Reputation points
2025-12-05T04:05:14.2966667+00:00

Can anyone here help me with the error code 399287?

I have just change into new phone but I forget to migrate data in Authenticator app, I can use my mobile number normally but Microsoft login page reject my number to get the OTP.

I cannnot login to the account now.

My email address is "PII removed"

PS> I am an admin of the company domain here too.

Regards,

Moved from Microsoft 365 and Office | Subscription, account, billing | For business | Windows

Microsoft Security | Microsoft Entra | Microsoft Entra ID
Answer accepted by question author
  1. Sridevi Machavarapu 8,285 Reputation points Microsoft External Staff Moderator
    2025-12-05T11:08:16.32+00:00

    Hello Nutthawut Tangudomsiri,

    Thank you for sharing your details (user's email address, tenant id, phone number, country code and country) with us over Private Message

    I have reached out to the engineering team to unblock MFA for your account. They have now unblocked it from the backend and removed the bad reputation on it. You should be able to log in to the Azure Portal without any issues.

    Please try logging in and check if you can complete SMS authentication without any errors. Let me know if you encounter any issues.

    I hope this information is helpful. Please feel free to reach out if you have any further questions.

    If the answer is helpful, please click on Accept Answer and Yes for was this answer helpful, which may help members with similar questions. If you have extra questions about this answer, please click "Comment". Thanks

    1 person found this answer helpful.

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