I am experiencing an issue while trying to log in to my Microsoft 365 Business Account.

Question

While attempting to log into my bussines account, I was asked for phone number text verification. However, during the verification process, it displays the following error:

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

Troubleshooting details

Error Code: 399287

Request Id: [Moderator note: personal info removed]

Correlation Id: [Moderator note: personal info removed]

Timestamp: [Moderator note: personal info removed]

My account information is: *******@***********.onmicrosoft.com

Assistance in resolving this issue as soon as possible would be greatly appreciated. Please let me know if any additional information is required.

Answer 1

Hi @ASECO,

Thank you for message regarding the problem you are experiencing with accessing your business account.

Error 399287 typically occurs when the phone number used for SMS or call MFA is flagged by Microsoft’s Phone Reputation system, often due to repeated failed attempts or activity that appears unusual. When this happens, SMS and call verification are temporarily blocked to protect your account. To resolve this, the affected MFA method typically needs to be reset.

Based on the details you shared, for your convenience, I will outline the available solutions below for both administrator account and end‑user account scenarios, so you can review the options that best apply to your situation.

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Scenario 1: You are an end user, or your organization has another IT administrator

If you are either an admin or end-user in your company, please contact other IT admins who still have access and share with them the steps outlined in the article Manage user authentication methods for Microsoft Entra multifactor authentication. This will help them assist you in resetting your MFA settings and restoring access to the account.

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Scenario 2: You are the only IT administrator in your organization

If you are the sole global administrator and cannot access your account, you will need assistance from Microsoft’s Data Protection team. They will verify domain ownership and other required information in order to restore your access.

You can proceed with one of these approaches:

Option 1: Contact Microsoft Data Protection Support by phone (Please proceed with the second option if contacting phone support is not applicable to your situation)

If you are the only administrator and there are no other admins who can still access the tenant, Microsoft’s Data Protection team has processes in place to verify ownership and help restore access to administrator accounts. You can try reaching out to the Global Customer Service phone to raise a request for resetting your authentication method here: Customer service phone numbers - Microsoft Support. During the call, request to speak to an agent, and share with them every detail related to your query and also mention that you are the only admin who lost access to your account. This should allow you to contact the appropriate team so you can solve this incident as soon as possible.

Please note that forum moderators do not have access to user account settings and cannot assist with logging in, resetting passwords, or changing access rights. While we do not have access to internal systems or administrative tools required to resolve account-specific or backend-related issues but we’ll continue doing our best to support you within the scope of our responsibilities.

You’ll need to verify your ownership of the Microsoft 365 tenant with Microsoft’s Data Protection Team. This verification process typically requires providing the following documentation:

• Proof of domain ownership, such as access to manage DNS records
• Billing or subscription information, including payment methods or account history
• The Tenant ID of the affected Microsoft 365 organization
• Official business registration documents
• Documentation confirming you are an authorized signatory for the business

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Option 2: Create a new tenant to submit a support ticket (Alternative method)

If you cannot reach a live agent, there is still a workaround, you might consider registering for a new tenant by signing up for a trial subscription via this link Microsoft 365 Business Plans and Pricing | Microsoft 365. (please select "Try for free" under a business subscription).

When prompted, enter your email. You can use your personal email or create a new Microsoft personal account for this step. Then select Set up account to move forward.

From this step, the system should guide you through creating your tenant and assign you a default onmicrosoft.com domain.

Once set up, you can access the admin console of the new tenant and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant.

To create a support ticket: In the Microsoft 365 admin center > Help & Support.

In your ticket description, you'll need to clearly explain that you're trying to regain access to your previous Microsoft 365 tenant and need help from the Data Protection team. Here's a message you can use or adapt:

"Hello, I’m the only global admin, but I'm unable to access my previous Microsoft 365 tenant.

I created this new tenant solely to request assistance. I kindly ask to be connected with the Data Protection team to verify my identity and help me recover access to the original tenant.

This is urgent, as I rely on Microsoft 365 for my work and have been unable to operate for several days. I’m available to provide any documentation or verification needed to support the recovery process."

It is important to note: Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges. You may prefer the following resource for detailed instructions: Cancel your Microsoft business subscription in the Microsoft 365 admin center | Microsoft Learn.

I hope this helps you regain access to your account quickly. I'm glad to assist and truly hope the information provided has been useful. Please feel free to reach out anytime if you need further assistance.

If you find my post useful, kindly consider upvoting it. Doing so can assist others in the community who may have similar questions in finding solutions more quickly.

Thank you for your kindness and contributions to the forum.

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