No Authenticator message arriving when I try to access Teams of another organization.

Dear @Mark Slierings | FABRICations,

Thank you for the extra details.

From what you described, Microsoft Authenticator works when you sign in to your own organization, but it fails specifically when you try to access a partner organization’s Teams as a guest. This often happens when the partner tenant requires MFA for guests and your guest MFA registration in that tenant is outdated (commonly after a phone change)

I also would like to reconfirm following information:

When you changed phones, did you transfer/restore your MFA setup from the old phone to the new one, or did you set up Authenticator again from scratch (scan a new QR code / re-register)? If you switched phones without re-registering MFA for that tenant, the old linkage may still exist on their side.

When you tap your email account in Microsoft Authenticator, do you see an 8‑digit code shown as two groups of 4 digits (4+4), while the sign‑in page on your PC only allows a 6‑digit code? If yes, this strongly suggests the Authenticator entry you’re looking at does not match the sign‑in challenge for the partner tenant, so the code will not be accepted

In the meantime, I recommend those steps:

Step 1: Remove old Authenticator entries from your side.

Go to Security info and remove any old/outdated Authenticator entries (old device/phone), then ensure your current phone is registered.

Step 2: Clean up the partner org entry (if it looks “stuck”)

Go to Organizations, find the partner org, and Leave organization for any old/broken entry (you’ll need them to invite you again after

Step 3: If issue still persists, please ask the partner admin to reset your guest MFA in their tenant:

Entra admin center > Users > (your guest account) > Authentication methods > “Require re-register multifactor authentication” (optionally “Revoke MFA sessions”).

Thank you for your cooperation. I'm looking forward for your reply.

Dear @Mark Slierings | FABRICations,

From what you described, I understand that when you try to access a partner organization’s Microsoft Teams, you’re prompted to either approve a request in Microsoft Authenticator (but no approval notification reaches your phone) or use a verification code (but that method fails), so you can’t complete sign-in.

To better assistance, could you please confirm following information:

Are you trying to join a Teams meeting hosted by the partner organization while signed in, or access a partner organization’s Teams (teams, channels, chat, or files) as a guest?

Have you recently changed phones or reinstalled the Microsoft Authenticator app?

When you select “use a verification code” you said it doesn't work either, what exact message do you see? Please send a screenshot of that page/error.

In the meantime, I recommend ask the partner organization to reset your MFA registration for your guest account (often done by selecting “Require re-register multifactor authentication” for your guest user in their Microsoft Entra admin center). After they do this, you should be prompted to re-set up Authenticator during the next sign-in attempt.

Besides, if you didn't change your device, I suggest that restart your device then try again.

Tips (partner admin improvement): The partner organization can also consider enabling cross-tenant trust to trust MFA from your home tenant, which can reduce the need for separate MFA registration in the partner tenant.

For detail: Require multifactor authentication strength for external users | Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…

Please understand that the initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

Your detailed response will help us diagnose and investigate the issue more efficiently. If I misunderstood what you’re looking for, feel free to let me know or share a screenshot. I’d be happy to help further!

Thank you for your cooperation. I'm looking forward for your reply.

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