Global Admin locked out – SMS MFA error 399287 (phone number blocked)

Hi Rubén,

Welcome to the Microsoft Q&A forum.

Error code 399287 appears when the system detects unusual activity on an account that could potentially affect the security of the account and the information within the tenant. In this case, your phone number may be flagged by the system as having a "bad reputation."

To receive assistance with verifying and marking your phone number as safe, you will need to contact the Microsoft Data Protection team for further review and assistance.

1/ Contact Microsoft Data Protection Support by phone

Please find the appropriate support phone number for your region and contact Microsoft frontline support. Then, ask them to create a support ticket for you. You can refer to the following link:

Customer service phone numbers – Microsoft Support

Tips for navigating the IVR system (automated phone support)

To help you navigate the IVR system more effectively, please refer to the guidance below:

1. When calling the support number, you may hear an introduction for about 30 seconds, such as: "You can visit the link…". You can skip this and wait until the system presents the available options.
2. Then:
3.  
   • Press "1" to indicate that you are a business email user.
     • Press "1" again to select technical support.

In some regions, the initial interaction may be fully automated. Below is a sample dialogue that you can prepare in advance:

• What kind of problem are you experiencing? Answer: Authenticator
• What product are you using? Answer: Office 365 for business
• Is this for an education or business account? Answer: Business
• Are you an administrator? Answer: Yes
• Are there any other administrators in your organization? Answer: No. I am the only administrator in my tenant.
• Do you need to create a support request? Answer: Yes. I need to create a support ticket. Please connect me directly with the Data Protection team.

During the call, you may be asked to provide some 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 you with restoring access.

2/ Create a new tenant to submit a support ticket

If you are unable to reach a live support agent, you may consider an alternative option: creating a new tenant by signing up for a trial subscription and then submitting a support request from the new tenant.

To set up a new tenant, please follow the steps below:

Visit Microsoft 365 Business Plans and Pricing.

You can create a new tenant by following the instructions provided on the page. Once the setup is complete, you can access the Microsoft 365 Admin Center for the new tenant and submit a support ticket requesting to be connected with the Data Protection team for assistance with your previous tenant.

Follow the guided setup process to create a new account for the new tenant.

Once the tenant has been created, you can access the support portal and submit a support ticket regarding the account that you are currently unable to access.

In the ticket description, clearly explain that you are trying to regain access to your previous Microsoft 365 tenant and need assistance from the Data Protection team.

You can use or adapt the following message:

"

Hello,

I am currently unable to access my previous Microsoft 365 tenant because I have lost access to my MFA authentication method.

I created this new tenant solely for the purpose of requesting assistance. I kindly ask to be connected with the Data Protection team so that they can verify my identity and assist me in restoring access to my original tenant.

This is an urgent issue because I rely on Microsoft 365 for my work and have been unable to work for several days. I am available to provide any documentation or verification information required to support the recovery process.

"

Submit a support ticket

In the Microsoft 365 Admin Center, go to:

Support > Help & Support

Please remember to cancel the trial subscription after your issue has been resolved to avoid any unexpected charges. You can refer to the detailed instructions here:

Cancel your Microsoft business subscription in the Microsoft 365 Admin Center

I hope the information above helps you regain access to your account as soon as possible. I am glad to assist and sincerely hope that the information provided is helpful. If you need any further assistance, please feel free to reach out.

If the answer is helpful, please click "Yes" and kindly upvote it.

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