Microsoft 365 Error Codes

How to Fix Error 399287 When Sending a Phone Verification Code in Outlook

Nimra Malik Sep 29, 2026 872 views

Question details

The user needs to bypass or fix Error 399287 which blocks the delivery of a phone verification code during the two-step verification process.

How to Fix Error 399287 When Sending a Phone Verification Code in Outlook

Product: Microsoft Outlook / Microsoft 365
Device & OS: not provided
Scenario: Authenticating an account using two-step verification (MFA).
Observed behavior: Outlook displays Error 399287 and fails to send the required security verification code to the user's phone.

Before you start

Verify whether you are the sole Global Administrator for your organization or if there are other administrators available who can access the Microsoft Entra admin center.

Solution 1Recommended

Reset Authentication Methods via Another Global Administrator

Use this solution if your organization has multiple Global Administrators who can reset your Multi-Factor Authentication (MFA) settings.

Error 399287 often indicates that the account or phone verification method requires an additional security review. A secondary Global Administrator can clear the current MFA sessions and force a re-registration of your authentication methods.

Access Microsoft Entra admin center

Have the other Global Administrator log in to the Microsoft Entra admin center using their administrator credentials.

Locate the affected user account

Navigate to the 'Users' section in the left-hand menu and search for your specific account.

Require MFA re-registration

Select 'Authentication methods' from the user's profile menu, click on 'Require re-register MFA', and save the changes.

Set up phone verification again

Log back into your Outlook account. You will be prompted to set up your two-step verification from scratch, which should bypass the previous Error 399287.

Reset Authentication Methods via Another Global Administrator

Administrative Rights Required: Only users with Global Administrator privileges can perform these resets. Forum moderators and standard users do not have the required access.

Solution 2

Contact Microsoft Support or Data Protection Team

Use this approach if you are the only Global Administrator for your tenant and are completely locked out of the Microsoft Entra admin center.

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Frequently Asked Questions

Why does Error 399287 occur during two-step verification?

Error 399287 typically occurs when the Microsoft security system flags the account or the specific phone verification method for an additional security review, preventing the automated system from sending the SMS code.

Can a Microsoft community forum moderator fix my account?

No, forum moderators do not have the backend administrative rights or permissions to reset accounts, clear MFA sessions, or change your authentication settings.

What should I do if I am the only administrator and get locked out?

If you are the sole Global Administrator, you cannot reset the settings yourself. You must contact Microsoft Support by phone and ask to speak with the Data Protection team to verify your identity and regain access.

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