I am completely locked out of my Microsoft 365 Business tenant because the MFA verification (SMS) is not working

Dear @Marc Brown, 

Thank you for posting your question in the Microsoft Q&A forum. 

In case you are the only Global Admin and completely locked out: 

You might need to contact Data Protection Team via phone service number: Customer service phone numbers - Microsoft Support. The agent will be able to create a ticket for you under the affected tenant and then transfer this ticket to Data Protection team who could help you to reset your MFA. The biggest goal is to get past the IVR (automated system) to a live agent and emphasize this critically important security factor. Please try this script, speaking loudly, clearly, and patiently waiting for the machine to respond. First, when you call the hotline, they will ask you what kind of problem you are struggling with.  

Answer: Authenticator.  
A: What products do you use?  
B: Office 365 for business.  
Verification: Education or company account?  
B: For companies  
A: Are you an administrator?  
B: Yes.  
A: Are there any other administrators in your organization?  
B: No.  
A: I need one.... Service request?  
B: Yes  

If you still cannot reach to agent, there is still a workaround, you might consider registering for a new tenant by signing up for a trial subscription via this link Compare All Microsoft 365 Plans | Microsoft. This would allow you to create a trial tenant following the provided prompts. Once set up, you can access the admin console of the trial tenant and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant. Get support - Microsoft 365 admin | Microsoft Learn 

Note: Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.  

As a moderator, I do not have the tools to deep dive into your account. This is because Microsoft's data security protocols are very strict, and only Data Protection Team is equipped with the necessary tools to investigate your specific tenant.  

After gaining access, you should set up an additional secondary Global Admin account. That way, if there is a problem with the primary account, you can use the secondary account to reset MFA. And you should set up all available MFA methods (MFA app, SMS, etc.) to have a backup method in case it is needed. 

If anything is unclear or you get stuck on a step, please feel free to reach out. I’ll guide you further. 

Looking forward to your response! 

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