Unable to Sign In to Microsoft 365 Admin Center – Outlook Mobile Approval Not Received and Verification Fails

Lotfi GARZOUN 20 Reputation points
2026-07-01T19:27:36.3166667+00:00

Hello,

I am unable to access the Microsoft 365 Admin Center (https://admin.cloud.microsoft/).

When I try to sign in, I am prompted to "Approve a request on my Outlook mobile app", but I do not receive any notification in the Outlook mobile application.

If I select "I can't use my Outlook mobile app right now" and choose the alternative verification method (Text to phone number ending in XX31), I receive the following error message:

"Sorry, we're having trouble verifying your account. Please try again."

I currently use Microsoft Authenticator on my mobile device for authentication, but the Outlook mobile app appears to be the default sign-in method. The authentication methods section is greyed out, so I cannot change or update my sign-in verification methods.

Could you please advise on:

How to restore access to my account?

How to switch the default authentication method from Outlook mobile approval to Microsoft Authenticator?

Whether an administrator can reset or re-register my MFA methods?

Any troubleshooting steps to resolve this issue?

Thank you for your assistance.

Microsoft 365 and Office | Install, redeem, activate | For business | Other
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Answer accepted by question author
Kai-L 19,410 Reputation points Microsoft External Staff Moderator
2026-07-05T18:47:44.5133333+00:00

Dear Lotfi,

Thank you for your update.

If I understand correctly, you are the sole admin of your organization and are looking for a way to open a support case that can be escalated to the Data Protection team. For business accounts, the fastest path is to reach them by phone. You can follow this article to check global customer support phone number from your region.  

Customer service phone numbers - Microsoft Support  

 

Here are some tips and an example of a prompt to help you navigate the IVR more effectively:  

In some countries, it is an automated conversation like: First, when you call the hotline, it will be asked as follows:  

IVR: What kind of problem are you concerned about?  

You: Account recovery.  

IVR: What kind of product do you use?  

You: Office 365 for business.  

IVR confirmation: education or company account?  

You: For companies  

IVR: Are you an administrator?  

You: Yes.  

IVR: Do you have the other administrator in your organization?  

You: No.  

IVR: Do you need a... Service request?  

You: Yes, please connect me with the Data Protection team.

Please note that you may need to repeat this process a few times, availability can vary based on local business hours, and the term"Global Admin" should be clearly mentioned during the call.

Alternative, you can create a new tenant account and submit your request from there.   

To set up a new tenant, please follow these steps:  

  1. Visit Compare Office 365 Enterprise plans and pricing, choose any plan and click try for free to start a free trial.   
  2. Choose any plan (e.g., Business Basic, Standard, or Premium) and click "Try for free" to start a free trial.  
  3. Follow the guided setup process to create your new trial account.  
  4. Once the new tenant is created, you should be able to access its support portal and submit your ticket.  
  5. Log in to the Microsoft 365 admin center (admin.microsoft.com).  
  6. Navigate to Show all > Support > New service request  
  7. In the request, explain your situation in detail.  

The support team will guide you through the identity verification process to help you regain access to your account.  

Important notes:  

  • This new trial tenant does not grant you access to data or settings of your original locked tenant. It only serves as a temporary way to contact Microsoft support.  
  • Be prepared for Microsoft to want to verify your identity and administrator privileges for the old tenant.  
  • The processing time may be longer because you are contacting support from another tenant.  
  • Remember to cancel the trial subscription as soon as your original account is restored to avoid unwanted charges. You can do this in the Microsoft 365 admin center under Billing > Your products.

I hope this information is helpful and gives you a clear path forward. Should you have any further questions or need additional assistance, please do not hesitate to reach out, I'm always happy to help. Also, if you found this helpful, please consider clicking Accept Answer and giving it an upvote. This small action can go a long way toward helping others with the same issue find the solution more easily.

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  1. Lotfi GARZOUN 20 Reputation points
    2026-07-03T18:09:22.6766667+00:00

    Thank you for the detailed explanation.

    At my side, I still cannot access to the admin portal as expected. The MFA flow is still blocked: the “Approve request” notification is not delivered to my Outlook/Authenticator mobile app, and SMS/phone-based verification is also unavailable since the number is flagged/blocked for MFA delivery. As a result, I am unable to complete sign-in even though I am the tenant administrator.

    Because I am currently locked out of authentication methods in Microsoft Entra ID, I also cannot manage or reset MFA settings for the affected account from the admin portal.

    From what I understand, resolving a blocked number / reputation flag requires escalation to the Microsoft Data Protection team, but I could not find a direct way to open a ticket specifically to that team.

    Could you please clarify the correct procedure to submit this request? In particular, I need guidance on how to open a support case that can be escalated to the Data Protection team, since I cannot complete access to the admin center.

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  2. Kai-L 19,410 Reputation points Microsoft External Staff Moderator
    2026-07-01T20:07:23.17+00:00

    Dear Lotfi

    Good day, and I appreciate the detailed description of your issue. As a forum moderator, I genuinely wish I could directly access your account or step into the backend systems and resolve this for you. Unfortunately, my role here is limited to providing general guidance and solutions that you can apply from your side.

    From my research, Error 399287 means that Azure has blocked your phone number for SMS verification due to a"bad reputation" flag. When this happens, SMS or call-based MFA verification cannot be completed, which prevents you from signing in to your account. To recover access, you will need your IT administrator (or Microsoft Support) to reset your MFA and unblock the phone number from the Microsoft Entra Admin Center. If you don't know who your IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support 

    For detailed instructions, please refer to this Microsoft guide: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID 

    Once the block is lifted, please go to My Sign-Ins | Security Info and add Microsoft Authenticator as your sign-in method. Using Authenticator for future logins is more reliable than SMS and can help avoid similar reputation-based blocks going forward.

    If your IT administrator is unable to resolve this from their side, please ask them to submit a support ticket to the Microsoft Data Protection team on your behalf. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin.

    When opening the ticket, please share all the information you have provided here (including Error 399287, the account affected, and the phone number involved) so that the support case can be routed to the appropriate team as quickly as possible.

    I know this isn't the answer you were hoping for, and it's disappointing when the solutions aren't straightforward. Please know that as a forum moderator, directing you to the correct, specialized support is the most effective help I can provide from my position. I truly hope you get your issue resolved swiftly. Wishing you all the best. 

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".  

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

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  3. Lotfi GARZOUN 20 Reputation points
    2026-07-01T19:49:50.5166667+00:00

    The sign-in process asks me to approve a request in the Outlook mobile app, but I do not receive any notification. When I select "I can't use my Outlook mobile app right now" and choose the SMS verification option, I receive the following error:

    Error Code: 399287

    Request ID: [Moderator note: Personally Identifiable Information removed]

    Correlation ID: [Moderator note: Personally Identifiable Information removed]

    Timestamp: 2026-07-01T19:45:27Z

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