Sole Global Administrator locked out by MFA – Error 399287 – phone support IVR disconnects

Hi Micaela,

I hope you're doing well.

I’m truly sorry to hear that you’re currently unable to sign in. The error 399287 typically occurs when the phone number used for multi-factor authentication (MFA) has been flagged by Microsoft's PhoneReputation service due to a "bad reputation" or suspicious activity. This results in SMS or phone call verification being blocked—even if the number works for other Microsoft services

Since your account is also an admin account and there are no other available global administrators in your tenant, then the only way to regain access is contact Microsoft support. Please try locating the appropriate hotline for your region here: Customer service phone numbers - Microsoft Support 

In this situation, the Microsoft Data Protection team has tools and processes in place to verify identity and regain access to administrator accounts. 

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.     

I also recommend calling during business hours. In my experience, it can be difficult to get through to the correct support queue, and automated systems don't always work as expected. If you can't get through on your first try, I suggest trying again later or at a different time.

I know being locked out of the only admin account can be stressful, but contacting the Data Protection team is the correct path forward in this scenario.

I hope these steps help you create a support ticket successfully and move closer to regaining access to your administrator account. While I’m not able to intervene directly, guiding you to the right support team is the most effective help I can provide here. 

Hope you're able to get this resolved soon.

Thank you. I have already tried the Chile support number several times, but the IVR disconnects the call before I can reach an agent or create a service request. I will try again during business hours following the IVR steps you provided. If I am still unable to reach Data Protection, is there any alternative escalation path for a sole Global Administrator lockout?