Accessing Outlook on the web for business using organizational credentials.
Hi Billy,
Thank you for reaching out.
Sorry to hear you're having trouble signing in to your Microsoft account.
From what you've described, it sounds like your authentication phone number needs to be changed. Because you're using a work or school account, the authentication settings are managed by your organization's IT administrator. Unfortunately, this isn't something that can be reset from the user side.
I'd recommend reaching out to your organization's IT administrator and explaining that you're unable to sign in because your phone number has changed and you are no longer receiving authentication codes. You can specifically ask whether they can change your phone number.
You may also want to share the following Microsoft article with them: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | …
If you are unsure who your IT administrator is, you can refer to this official Microsoft guide for assistance: How do I find my Microsoft 365 admin? - Microsoft Support
Once your IT administrator changes your number, you should be able to sign in again and go through a process to set up a new MFA authentication method.
I hope this points you in the right direction. If you receive any updates from your IT team or run into any issues along the way, feel free to reply back with more details and I'll be happy to help further.
Best regards,