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Dear JohndoeMT,
Good day! Thanks for posting in the Microsoft Community. We are happy to help you.
According to its description, it looks like you're having issue accessing the developer account with Microsoft Authenticator after changing the phone.
If the above understanding is correct, we note that you have posted this topic in the "For Business" category, we assume that you may have problems with a work/school account with a subscription provided by the organization, for such accounts, Microsoft provides the subscription based on the organization. In each organization, Microsoft 365 admin privileges are required to manage accounts.
In this situation, we'd like to confirm that you're the only administrator for the organization. If you're not the organization's administrator, or if there's another administrator in the organization, please contact your M365 administrator to reset the authentication method for you. After that, you will be able to reset the verification and login again.
About how to find the admin in your organization, you can see How do I find my Microsoft 365 admin? - Microsoft Support
For your admin reference: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | Microsoft Learn
If you are the only admin in your organization who has been locked out of your account, please understand that as forum support, we may have limited resources and permission to help reset from the backend service account, more resources need to be involved to help you further.
In this situation, we suggest that you contact the Microsoft protection group Global Customer Service phone numbers - Microsoft Support, locate the number according to your Country/Region, and after calling, provide some necessary information to the agent, who will help you with the account/phone authentication issue and keep your account safe and secure.
We hope the above can help. If there are any updates or we don't understand you, feel free to let us know.
Your understanding and cooperation are highly appreciated. Thank you for your precious time. Have a nice day!
Sincerely
Rhoda | Microsoft Community Moderator