How to Fix Error Code: 399287

MZRV 0 Reputation points
2026-03-04T08:31:03.8166667+00:00

Unable to login to Microsoft account and admin center after buying of domain and change set domain to active email

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

Microsoft 365 and Office | Subscription, account, billing | For business | Other
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  1. AI answer

    2026-03-04T08:31:18.36+00:00

    Error code 399287 indicates that the phone number used for SMS verification has been flagged with a “bad reputation” and is blocked for MFA/identity verification. When this happens, sign-in and access to the Microsoft 365 admin center can fail if SMS is the only available second factor.

    To resolve this and regain access, Microsoft support (specifically the Microsoft Data Protection team) must reset or clear the MFA configuration on the account and remove the block so that sign-in can succeed again.

    Action steps:

    1. Contact Microsoft support and request MFA reset
      • Call the appropriate Microsoft customer service or support hotline for the region (see “Customer service phone numbers - Microsoft Support” from the context provided in the Q&A threads).
      • When prompted by the automated system, clearly state that the issue is with “Authenticator” or “SMS verification” and that sign-in is blocked by error 399287.
      • Indicate that this is for a Microsoft 365/Office 365 for business account and that the caller is the administrator.
      • Ask specifically for a service request with the Microsoft Data Protection team to:
        • Reset MFA for the admin account, and
        • Remove the “bad reputation” block on the phone number used for SMS verification.
    2. If unable to open a ticket from the locked tenant
      • If sign-in to the existing tenant is not possible at all, create a temporary Microsoft 365 trial tenant as described in the Q&A guidance:
        • Sign up for a Microsoft 365 trial plan and complete tenant creation.
        • Go to the Microsoft 365 admin center for the trial tenant.
        • Use Support → Help & support to open a support ticket.
        • In the ticket, clearly state that access is needed for a different, existing tenant where the admin is locked out due to error 399287/SMS MFA block, and request Data Protection team assistance.
      • After the original tenant access is restored, cancel the trial subscription to avoid charges.
    3. Be prepared to verify identity and domain ownership
      • Support may request information such as:
        • Admin account sign-in name.
        • Tenant domain name(s) (including any new custom domain just purchased and set as primary).
        • Proof of domain ownership (DNS or registrar details).
      • This is required before the Data Protection team can reset MFA or remove the phone-number block.

    Once the Data Protection team resets MFA and clears the phone number’s bad reputation flag, sign-in with the Microsoft account and access to the Microsoft 365 admin center should work again, and new MFA methods (Authenticator app, new phone number, etc.) can be configured.

    References:

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  2. Jess-Q 12,795 Reputation points Microsoft External Staff Moderator
    2026-03-04T09:41:08.93+00:00

    Hi @MZRV

    Thank you for posting your question in the Microsoft Q&A forum.  

    Regarding your issue, the error code 399287 you encountered typically means the phone number used for verification has been flagged by Microsoft's PhoneReputation service due to a "bad reputation" or suspicious activity.  

    If you are the only global admin and locked out you must contact Microsoft Support for help: Customer service phone numbers.

    Please remember to provide them with your account details and explain the situation. Be ready to provide:     

    • The company name used during subscription    
    • Billing email address (even if it’s a personal Microsoft account)    
    • Payment method details (last 4 digits of the card, billing address)    
    • Any subscription ID or invoice numbers from billing email    

    When you call the support number, you may hear an introduction of about 30 seconds such as "you can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.

    To make the process smoother, here’s an example of how to respond when speaking to the automated system (IVR):     

    IVR: What kind of problem are you concerned about?     

    You:  Authenticator.    

    IVR: What kind of product do you use?     

    You: Office 365 for business.     

    IVR: education or company account?     

    You: For companies     

    IVR: Are you an administrator?     

    You: Yes.     

    IVR: Do you have the other administrator in your organization?     

    You: No.     

    IVR: Do you need a... Service request?     

    You: Yes     

    These prompts help direct your call to the right support team more quickly, especially when dealing with account lockouts and authentication issues. 

    If you still cannot reach to agent, there is still a workaround, you might consider registering for a new tenant by signing up for a trial subscription via this link Compare All Microsoft 365 Plans. This would allow you to create a new tenant following the provided prompts.    

    • Follow the guided setup to create a new Microsoft account and a new tenant.
    • This tenant will be completely separate from your existing Microsoft 365 environment.

    Once set up, you can access the admin console of the new tenant by logging into admin center and follow the steps in this article: Get support - Microsoft 365 admin and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant.    

    Include the following details:

    • The administrator email address for the locked tenant
    • The domain name of the locked tenant
    • Any error messages you are seeing
    • A description of the authentication or sign‑in issues
    • Confirmation that you are the administrator of the locked tenant

    Before submitting the ticket, make sure the Support Assistant is turned Off as several customers have reported that when the Support Assistant is enabled, the Contact Support option may not appear.

    As shown in the screenshot, simply switch Support Assistant > Off, then enter your issue description. Once disabled, the Contact Support button should appear, allowing you to submit the ticket normally.

    User's image

    Important note:

    • This new trial tenant does not provide access to any data, users, or settings from your original locked tenant. It is only intended as a temporary way to contact Microsoft Support.
    • Once the issue with your original tenant is resolved, be sure to cancel the trial subscription to avoid any unintended charges. You can do this from the Microsoft 365 Admin Center by going to Billing > Your products and canceling the trial there.

    Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.

    As forum moderators, we don’t have access to the detailed system needed to troubleshoot this effectively due to privacy and security constraints. To quickly resolve this and regain access, the most effective step is to contact Microsoft Support Team directly. Only they have the ability to help with your Authenticator issue.    

    Hopefully it will help work with your issue and if you have any other questions or need further assistance, feel free to ask.   

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".   

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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