MFA SMS and phone call verification failing with Error Code 399287 on Microsoft Entra work account

Question

MFA SMS and phone call verification failing with Error Code 399287 on Microsoft Entra work account

AHMED BOUKTIR 0

Hello,

I am unable to access my Microsoft Entra work/school account because MFA verification by phone is failing.

My account belongs to an educational organization in Morocco.

My username and password are accepted correctly, but Microsoft then requires MFA verification using the phone number already registered on my account.

I have tried both available verification methods:

SMS verification: Microsoft says that the verification code was sent, but no SMS is received.
Phone call verification: the call fails immediately and Microsoft displays Error Code: 399287.

I confirmed that the registered phone number is still active and correct. The phone can normally receive regular SMS messages and incoming calls.

I also tested again using a completely new private browser session, but the phone verification failed again with Error Code 399287.

The latest diagnostic information displayed by Microsoft is:

Error Code: 399287 Request ID: [Moderator note: Personally Identifiable Information removed] Correlation ID: [Moderator note: Personally Identifiable Information removed] Timestamp: 2026-09-14T10:12:59Z

I also tested the Microsoft self-service password reset flow. It successfully recognized my registered phone number and reported that an SMS verification code had been sent, but that SMS did not arrive either.

Could a Microsoft moderator or support engineer please advise whether Error 399287 may indicate that phone/SMS MFA verification is being blocked on the Microsoft side, and whether the MFA/phone reputation status for this account or phone number needs to be reviewed?

If private account or phone information is required for investigation, I can provide it through a secure/private channel. I do not want to post sensitive information publicly.

My organization administrator has also been contacted regarding an MFA reset/re-registration.

Thank you.

Moved from Microsoft Security | Microsoft Entra | Microsoft Entra ID

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1 answer

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Answer 1

Dear AHMED BOUKTIR,

Based on the information you provided, particularly Error Code 399287, and the fact that both SMS and phone call verification are failing even though your phone can receive normal calls and text messages, the issue may be related to the authentication method rather than your password or browser.

Since this account belongs to an educational organization, I recommend contacting your organization's IT administrator and asking them to review your authentication methods in the Microsoft Entra admin.

Sign in to the entra.microsoft.com as at least one Authentication Administrator.
Select User > All user. Select the user (your account) to act on and select Authentication methods then select Require re-register of multi-factor authentication.

Require re-register MFA: This disables all previous authentication methods. You'll then be prompted to configure a new MFA authentication method the next time you try to sign in, so you can set up from the start and add a new authenticator app.

Untitled

They can follow the steps in this article to reset your MFA settings: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | Microsoft Learn

Note: Once re-registration is triggered, all your existing MFA methods such as phone numbers, Authenticator app, or other verification options will be removed. You will need to set up new MFA methods during your next login. Please ensure you have access to a valid phone number or the Microsoft Authenticator app before attempting to sign in again.

I appreciate your patience, and I am here to help. Looking forward to your response!