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Cannot login using SMS as MFA

Mike Pantelidakis 20 Reputation points
2026-01-14T08:59:30.7166667+00:00

Hello there.

I have an issue logging in to my work account. I have account work account but when I try to login I cannot use MFA using SMS as I am getting error 399287 when trying to send the message. I don't have other MFA method configured so I cannot access setting to change that. Can you please remove my number from block list?

Error Code: 399287

Request Id: 7daa6596-91ce-43b3-9509-0faf3ff61200

Correlation Id: 2c10908a-61c6-4c65-820b-5038031a7d36

Timestamp: 2026-01-14T08:49:36Z

Microsoft Security | Microsoft Entra | Microsoft Entra ID

Answer accepted by question author

  1. Shubham Sharma 15,500 Reputation points Microsoft External Staff Moderator
    2026-01-14T11:57:12.77+00:00

    Mike Pantelidakis

    Thank you for sharing your details via private message.

    I’ve reached out to the engineering team regarding the MFA issue on your account. They have now unblocked it from the backend and cleared the bad reputation associated with it. You should be able to log in to the Azure Portal without any issues.

    Please try signing in and verify if you can complete SMS authentication successfully. Let me know if you encounter any problems.

    As a best practice, I recommend registering the Microsoft Authenticator method for your account instead of relying on SMS. SMS and voice call authentication methods are more vulnerable to IRSF attacks (telephony fraud) and are generally less secure.

    For better practice, I recommend registering with Microsoft Authenticator method to your account instead of SMS method as these SMS/Voice telecom auth methods are susceptible to IRSF attacks telephony fraud.

    If the query has been resolved, please take a moment to accept the answer and upvote it 👍 to make it helpful to the community.

    Thank you for helping to improve Microsoft Q&A!

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    1 person found this answer helpful.

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