I recieve Error Code: 399287 when use MFA via phone call

Petr Bláha 20 Reputation points
2025-10-16T09:25:50.3333333+00:00

I am writing in urgent need of resolution for this critical blocking issue affecting my Azure web access. As the sole administrator of this account, being unable to log into Azure via the web interface is severely impacting my ability to manage services and conduct research operations.

I recieve Error Code: 399287 when use MFA via phone call

Error Code: 399287

Request Id: Removed PII

Correlation Id: Removed PII

Timestamp: Removed PII

Thank you for help!

Microsoft Security | Microsoft Entra | Microsoft Entra ID
Answer accepted by question author
Raja Pothuraju 47,835 Reputation points Microsoft Employee Moderator
2025-10-16T13:58:53.81+00:00

Hello @Petr Bláha,

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.

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

Was this answer helpful?

1 additional answer

Sort by: Most helpful
Most helpful Newest Oldest
  1. SUNOJ KUMAR YELURU 18,736 Reputation points MVP Volunteer Moderator
    2025-10-16T10:45:49.5633333+00:00

    Hello @Petr Bláha

    Error Code 399287 during MFA phone call authentication typically indicates an issue with the phone number configuration, service health, Conditional Access policies, or a corrupted MFA registration. Follow the troubleshooting steps, starting with verifying the phone number and ending with contacting Microsoft Support if necessary.

    • Always verify the phone number format, including the international dialing code.
    • Check Azure Service Health for any reported incidents.
    • If you are the sole administrator and locked out, use the Azure account recovery process.
    • Provide the Error Code, Request ID, and Correlation ID when contacting Microsoft Support to expedite the troubleshooting process.

    If the Answer is helpful, please click Accept Answer and Up-Vote, so that it can help others in the community looking for help on similar topics.

    Was this answer helpful?

    0 comments

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.