Microsoft Office 365 MFA
You no longer have the phone number to verify your office 365 account!
If you have access to Microsoft 365 admin center, Submit service request in your Microsoft 365 Admin center to get callback from support engineer.
Go to the admin center at https://admin.microsoft.com.
On the bottom right side of the page, select Help & support.
Type a question or keyword into the text box. If you get a drop-down list, select the one closest to your question, or continue typing your question, then press Enter.
If the results don't help, at the bottom, select Contact Support.
Call hotline as link Get support - Microsoft 365 admin | Microsoft Learn with selected country. Call hotline - 30 seconds for opening, then press 1 as business email user, press 2 as billing support to reach us.