Error code: 399287 when doing MFA with SMS

Question

Hi support,

I'm helping when which currently have an issue to his Global Admin account. He need to change credit card because current one is expired.

He has the correct username/password for his Admin account, but lost the Authenticator app. Other say to sign with cod by SMS is possible and should be with correct phone number.

As I see in other cases it looks like Microsoft have block the number.

He get's Error code: 399287 - same as in this case: https://learn.microsoft.com/en-us/answers/questions/5562870/error-code-399287

How can Microsoft or we whitelist the number again so he can change the credit card and reconnect Autherticator app?

Hope to hear from someone as soon as possible, thanks!

Answer 1

Hi @Peter Enoch,

Welcome to the Microsoft Q&A forum.

Thank you for contacting us. I would like to provide you with the following information:

As you described, Microsoft has indeed flagged this phone number as having a bad reputation.

Error code 399287 appears when the system detects abnormal or suspicious behavior on the device. Such behavior may potentially impact the customer’s tenant.

In this case, the Data Protection Team is the only Microsoft department that has the necessary tools to review the customer’s device and confirm that it is safe within Microsoft’s systems. (Note: The device verification process does not access or violate the customer’s personal data.)

Currently, there are three ways to contact Microsoft’s Data Protection Team:

1. If you have another Global Administrator account

Tip: This Global Administrator account does not need to belong to the affected tenant. You may use it as an alternative account to contact Microsoft’s Data Protection Team.

2. Contact Microsoft via hotline

You can contact Microsoft Support through the official hotline number for your region.

3. If you do not have another Global Administrator account

Similar to option 1, you can create a Microsoft trial tenant, use it to create a support ticket, and then disable auto-renewal for that tenant.

 

Important notes:

• The effectiveness of creating a support ticket versus contacting Microsoft via hotline may vary.
• When contacting Microsoft by phone, you will initially interact with an AI bot. After the bot collects the required information, your case will be transferred to a support agent.
• In some cases, the AI bot may not fully capture the issue. If that happens, we recommend using option 1 or option 3 to contact the Data Protection Team directly.
• Forum moderators do not have the authority to directly intervene in user accounts, especially for issues related to:
  • Account sign-in
  • Password reset
  • MFA authentication
  • Changing or restoring account access

1. If you have another Global Administrator account

Please follow the steps below to create a support ticket:

1. Go to admin.microsoft.com
2. Select Help & Support
3. Enter the title: Request to contact the Data Protection Team
4. Select Contact Support
5. Choose your preferred contact method

2/ If you do not have another Global Administrator account

Please visit the link below to obtain the Microsoft support phone number for your region:

Customer service phone numbers - Microsoft Support

Tips for navigating the IVR system (automated phone support):

• When calling the support number, you may hear an introduction for about 30 seconds (for example: “You can visit the link…”). You can skip this and wait for the menu options.
• Then:
  • Press “1” – Business email user
  • Press “1” again – Technical support

In some regions, the initial interaction is fully automated. You can prepare the following responses in advance:

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

During the call, you may be asked to provide subscription-related information such as:

• Company name
• Billing information
• Phone number
• Alternate email address

This information helps the Data Protection Team verify your identity and securely assist with restoring access.

 

3. If you cannot contact Microsoft via hotline and do not have another Global Administrator account

You can create a Microsoft trial tenant using the link below, then follow the same steps as in option 1 to create a support ticket:

Microsoft 365 Business Plans and Pricing | Microsoft 365

Important notes:

• This trial tenant does not grant access to the data or settings of the locked tenant. It is only used as a temporary method to contact Microsoft Support.
• Microsoft Support may require identity verification and proof of tenant ownership.
• The resolution process may take longer since you are contacting support from a different tenant
• Do not forget to cancel the trial subscription after the issue with the original tenant is resolved to avoid unexpected charges.

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this.   

Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.

I look forward to continuing the conversation.

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Answer 2

This is a one man company with only one user. His normal account is working fine, but that does not have Global Admin rights. The Account with Global Admin rights works (username/password), but cannot use SMS code because number seems to be blocked at Microsoft.

How can he/we contact Microsoft so the number can be unblocked?

Answer 3

To resolve the issue with Error Code 399287, which indicates that the phone number has been blocked for SMS verification due to a "bad reputation" flag, the user will need to contact Microsoft support. This is a known issue, and typically, the Microsoft Data Protection team can assist in resetting the Multi-Factor Authentication (MFA) settings or whitelisting the phone number again.

The user can reach out to the Global Admins of their tenant to request a re-registration of MFA. This will allow the user to configure their MFA methods again, including the option to use SMS verification if the phone number is unblocked.

It's important to ensure that the correct phone number is associated with the account and that the user provides any necessary information to support when requesting assistance.

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References:

• Unable to Verify Identity for Azure Login – Error 399287
• Azure has blocked my phone number for SMS verification due to a "bad reputation" flag