Cannot verify my account through SMS (Error Code: 399287)

Question

I am trying to sign in to my account. I do know all the account details such as email address and password. Upon login a security code should be sent to my phone. The phone number the message would be sent to is also mine. Unfortunately, I get the message: "Sorry, we're having trouble verifying your account. Please try again". Now, I cannot acccess my account anymore. This is a business account. I also cannot access my Authencator
Error Code: 399287

Request Id: [Moderator note: personal info removed] 

Correlation Id: [Moderator note: personal info removed]

Timestamp: 2026-04-28T03:56:12Z

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 @Nguyễn Thành Kiệt,

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 code 399287 indicates that the phone number used for SMS verification has been blocked due to a “bad reputation” or similar risk-based block on SMS for that number. In this situation, self-service fixes are not available and the block must be cleared by Microsoft support.

For a business/work account where SMS and Authenticator are both unavailable, the documented resolution is to involve Microsoft’s Data Protection / Microsoft 365 support team so they can reset MFA or clear the block after verifying identity and admin ownership.

Recommended actions:

1. Engage Microsoft support for the tenant
   • If this is an organizational (work) account and there is at least one other global admin, that admin should:
     • Sign in to the Microsoft 365 admin center for the tenant.
     • Open a support request describing:
       • That sign-in fails at SMS verification with error 399287.
       • That the phone number appears to have a bad reputation and SMS is blocked.
       • That Authenticator is also unavailable.
   • If this is the only admin account for the tenant (single-admin scenario), Microsoft’s Data Protection team must verify identity and reset MFA from their side.
2. If this is a single-admin tenant and sign-in is impossible
   • Use the documented escalation path to reach the Microsoft Data Protection team:
     • Call the regional Microsoft customer service number and follow the automated prompts to open a service request for “Authenticator / Office 365 for business / company account / administrator locked out, no other admins.”
     • Alternatively, if no existing tenant can be accessed at all, create a temporary Microsoft 365 trial tenant, go to the new tenant’s admin center, and open a support ticket clearly stating that the issue is with a different, existing tenant where the admin is locked out and getting error 399287 on SMS.
   • Provide to support (only directly to Microsoft, not publicly):
     • The affected tenant domain.
     • The admin UPN/email.
     • The error code (399287) and recent timestamps.
     • That SMS MFA is blocked and Authenticator cannot be used.
   • The Microsoft Data Protection team can then:
     • Verify identity and admin ownership.
     • Reset MFA or clear the bad-reputation block on the phone number.
3. After Microsoft resets MFA / clears the block
   • Sign in again and complete MFA setup when prompted.
   • Add at least two independent MFA methods (for example, Microsoft Authenticator plus an alternate phone or email, where allowed) to avoid being locked out if one method fails.

Because error 399287 is tied to a reputation/block on the phone number, waiting or retrying will not typically resolve it; direct Microsoft support intervention is required to reset MFA or remove the block.

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References:

• Troubleshoot Microsoft verification code issues
• 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 have a Micrsoft business account and I am the admin and the only user registered under this account. I can't log in because i have replaced my phone and the authenticator doesn't work. - Microsoft Q&A