Error 399287, bad reputation issue

Question

Dear Microsoft Support Team,

I'm trying to sign into the Microsoft 365 portal. I can sign in to my Microsoft account, but I'm prompted to verify my identity via SMS. However, I receive the following error message:

“Sorry, we’re having trouble verifying your account. Please try again.”

Error Code: 399287

I have already tried alternative login methods and password reset options but have been unable to complete the identity verification process. I would appreciate your assistance in resolving this issue as soon as possible as it is a business account. It would be great if you could unblock the MFA to the account. I am using another email to post this question since i am not able to access my business account). You can contact me on this email.

Thank you for your kind support

Best Regards,

Nikola

Answer 1

Please understand that as forum moderators, we do not have the tools or sufficient access to make changes to user accounts, including logging in, resetting passwords, or modifying access rights. For your security, only Microsoft Support can assist with these requests. However, I will do my best to guide you using publicly available documentation, research, and community experience.  

Hello @Nikola Skopljak,

Welcome to Microsoft Q&A Forum!  

To better understand your situation and guide you correctly, could you please confirm whether you are an end user or a global administrator of your Microsoft 365 tenant?  

The next steps will depend on your role:  

1. If you are an end user  

The quickest and most effective solution is to contact your organization’s IT administrator. They can revoke your current Multi‑Factor Authentication (MFA) settings and allow you to re‑register.   

You may share this official Microsoft article with them for detailed guidance: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…    

2. If you are an administrator  

Please check whether there is another admin in your tenant. If so, they can reset your MFA configuration by:  

• Signing in to the Microsoft Entra Admin Center  
• Navigating to Users > Your Account > Authentication methods  
• Selecting Require re‑register MFA  

You will then be prompted to set up MFA again at your next login.  

3. If you are the only administrator  

In this case, you will need to contact Microsoft’s Data Protection team, who are authorized to verify your identity and reset MFA settings. Please call Microsoft Support using the appropriate regional hotline listed here: Customer service phone numbers - Microsoft Support  

Here are some tips and an example of a prompt to help you navigate the IVR more effectively:   

(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.)     

In some regions, the initial interaction may be automated, so here’s a general idea of how the conversation might go to help you prepare:       

• What kind of problem are you experiencing?          
• Answer: Authenticator          
• What products do you use?          
• Answer: Office 365 for business          
• Is this for an education or company account?          
• Answer: For companies          
• Are you an administrator?          
• Answer: Yes          
• Are there any other administrators in your organization?          
• Answer: No. I am the only admin in my tenant           
• Do you need a... Service request?           
• Answer: Yes. I need to create a ticket. Please send me direct to the Data Protection Teams.       

During the phone call, you will need to provide the information associated with your subscription, such as your company name, billing details, phone number, and an alternate email address, etc. This information allows the Data Protection team to verify your identity and securely assist you in regaining access to your administrator account.      

Could you please confirm which of the three cases applies to you? Once I have this information, I can guide you further and ensure you get the correct next steps.  

Thank you, and I look forward to your reply. 

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Answer 2

Error 399287 indicates that the phone number used for SMS verification has been flagged with a “bad reputation” and Azure has blocked it for SMS-based MFA. This cannot be fixed from the user side and requires admin/support intervention.

For a business (work) Microsoft 365 account, the resolution path is:

1. Contact the organization’s Microsoft 365/Entra ID admin
   • Ask a global admin in the tenant to reset or re-register the MFA methods for the affected account.
   • Admins can use the “Require re-register MFA” option so that new MFA methods (such as Microsoft Authenticator or a different phone number) can be configured. See: “Require re-register MFA so that you can configure the MFA methods again.”
2. If no admin can fix it or the only global admin is locked out
   • This becomes a tenant lockout scenario where no one with sufficient rights can reset MFA.
   • In such cases, Microsoft support must engage the Data Protection team to reset MFA and restore access. This is how similar cases with error 399287 and tenant lockout have been resolved:
     • “The Microsoft Data team has reset my MFA and solved the issue.”
     • “We have engaged our Data Protection team through a support ticket. They will help restore access to the tenant and assist in resolving the issue.”
3. Open a support ticket with Microsoft
   • Since this is a business account and MFA is blocking access, a support ticket needs to be created from the tenant (if any admin is still signed in) or via Microsoft 365 support channels.
   • In the ticket, clearly state:
     • Error code 399287
     • That SMS verification is blocked due to bad reputation
     • That this is a business/tenant account and MFA must be reset/unblocked
   • Support will route the case to the Data Protection team to remove the block/reset MFA.
4. After Microsoft resets MFA
   • Sign in again and register new MFA methods (preferably Microsoft Authenticator app and/or a different phone number) when prompted.

If this is a personal Microsoft account instead of a corporate-managed account, use the Microsoft account sign-in helper and recovery guidance, and if still blocked, contact Microsoft Support via the official “Contact Microsoft Support” flow for further assistance.

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References:

• 399287 - Microsoft Q&A Unable to Verify Identity for Azure Login – Error 399287
• Azure has blocked myphone number for SMS verification due to a “bad reputation” flag - Microsoft Q&A I try to login via SMS because my phone was reset and now I am getting:
• I need to reset my mfa methods - Microsoft Q&A I need to reset my mfa methods because i reset my phone and cant get to my authenticator app, maybe if i can add a phone number to my account
• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A Got a new phone, and can't access my Microsoft Authenticator app from the old phone. Locked out of the account. Business down. There is only one global admin on the account. Have all business documentation and information.
• I can't sign in to my Microsoft account
• Troubleshoot Microsoft verification code issues
• Customer Support Portal - Troubleshoot Microsoft Identity Platform login