Can an External Teams user access a custom app added to a meeting by the organiser

Question

Can an External Teams user access a custom app added to a meeting by the organiser

Philip Hendry 0

I'm developing a tab app for Microsoft Teams which can be added to meetings/town halls/webinars by the organiser so participants can access the app during the meeting. The app itself is a basic static tab and just a host for our web application which is already accessible on a public URL.

The app works perfectly when participants are members of the organisation that set up the meeting and I've also managed to make it work for anonymous users (though only anonymously from within the desktop app and not in a browser!)

However, I'm yet to see it work for an External Teams user. Although I don't have another organisation to test a user from, is there a critical difference between an External user from an organisations (Work and Schools account) as opposed to one with a Personal Microsoft account such that the latter won't ever work??

Sayali-MSFT 4,356 Reputation points Microsoft External Staff Moderator

2025-12-09T05:32:27.9933333+00:00

Hello Philip Hendry ,Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.

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Sayali-MSFT 4,356 Reputation points Microsoft External Staff Moderator

2025-12-09T05:32:27.9933333+00:00

Hello Philip Hendry ,Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.

Answer 1

Hello @Philip Hendry ,
External users with Work or School (Azure AD) accounts can access meeting apps in Teams when the organizer adds the app and they join via the desktop or mobile client. Users with Personal Microsoft Accounts (MSA) cannot use meeting apps at all—this is a permanent, documented limitation.

This restriction exists because meeting apps rely on organizational Entra ID policies that personal accounts don’t support.

As workaround Provide a deep link in meeting chat:

https://teams.microsoft.com/l/entity/{appId}/{entityId}?webUrl=https://yourapp.com

Offer a standalone web experience for personal account users.
Use Adaptive Cards for lightweight interactions in chat.

Reference Document-
https://dori-uw-1.kuma-moon.com/en-us/microsoftteams/platform/apps-in-teams-meetings/build-apps-for-anonymous-user?tabs=javascript

Philip Hendry 0 Reputation points

2025-12-12T08:32:17.8266667+00:00

Thank you @Sayali-MSFT , your response is direct and very useful indeed. I'll come back with a comment once I've managed to finalise my app and test the deep linking as I think this answer will help others too.

Answer 2

Teddie-D 9,045 Microsoft External Staff Moderator

Hi @Philip Hendry

Thank you for posting your question in the Microsoft Q&A forum.

There is an important distinction between these two types of external users:

Personal Microsoft accounts

-External access for personal Microsoft accounts only supports chat with Teams users in an organization.

-Personal Microsoft accounts cannot join meetings as authenticated external participants, because they are not Entra ID–backed identities.

-They can join meetings only as anonymous users through a meeting link.

-Anonymous participants cannot add or manage meeting apps; they can only interact with apps pre-installed by the organizer in a limited, unauthenticated mode.

-Meeting apps require an Azure AD identity, since app permissions and SSO depend on organizational context.

External Work or school accounts

These are users from another organization’s Azure AD tenant.

If your app is configured for multi-tenant in Azure AD (App Registration > Supported account types: Accounts in any organizational directory), external users from other organizations can access it if:

-The meeting organizer’s tenant allows external participants.

-The app is installed in the meeting and permissions are granted.

These users authenticate via their organizational credentials, so your app can rely on standard Teams SSO or OAuth flows.

References:

I hope this information is helpful.

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Philip Hendry 0 Reputation points

2025-12-09T14:01:31.2966667+00:00

Many thanks for your resonse. It doesn't quite answer my question yet though you've mentioned exactly the area I'm struggling to answer. In particular, and for Personal accounts you stated:

"-Anonymous participants cannot add or manage meeting apps; they can only interact with apps pre-installed by the organizer in a limited, unauthenticated mode."

I think I need to understand what you've said here and how it relates to my problem. If I set up a meeting, add my app, then invite a participant to join, if that participant has logged in to Teams with the personal account then they cannot view the shared app. If, however, they join without logging in then they can view the shared app. Is this latter scenario what you described as "unauthenticated mode"? I had thought that users who have logged in with a Personal account join the meeting as an anonymous user but the documentation seems confusing at this point. But this is the specific scenario I'm trying to ascertain is possible or not. If may just be that I've missed a specific setting in the Teams admin center?
Teddie-D 9,045 Reputation points Microsoft External Staff Moderator

2025-12-10T10:40:19.37+00:00

Hi @Philip Hendry

Sorry if my earlier response caused any confusion. Here’s a clearer explanation:

When someone joins a Teams meeting, meeting apps only work in two supported identity scenarios:

-They join using a Work or school account

In this case, the user is fully authenticated through Microsoft Entra ID. Meeting apps can use single sign-on and tenant permissions, so the app loads normally.

-They join as a truly anonymous user (not signed in to any Microsoft account)

In this case, the meeting app can still load, but only in a limited, unauthenticated mode. The user can view and interact only with the public parts of the app that were added by the organizer.

However, when a user joins the meeting while signed in with a personal Microsoft account such as Outlook.com or Hotmail, they fall outside of both supported scenarios:

-They are not an organizational (Work or school) user, so the app cannot authenticate them.

-They are also not treated as truly anonymous, because they are still signed in to Microsoft.

As a result, the Teams platform has no supported way to run the meeting app for this type of user, and the app does not load at all. This is expected platform behavior, not a configuration issue in the tenant.

At this time, there is no Teams admin setting that can change this behavior.
Teddie-D 9,045 Reputation points Microsoft External Staff Moderator

2025-12-11T06:48:56.06+00:00

Hi @Philip Hendry
Please let me know whether this explanation clarifies the issue. I’m glad to provide further detail if needed.
Philip Hendry 0 Reputation points

2025-12-12T08:30:00.6666667+00:00

Thanks @Teddie-D

Your reply has indeed helped along with @Sayali-MSFT response - you've both helped confirm what, unfortunately, I had feared was the answer. WHilst the application I'm creating would work for big organisation who have all users with Work accounts, we're also targetting clubs & societies whose members are unlikely to have a Work account though they will be likely to have a Microsoft Personal account. But now I'm "armed with reality" and can re-approach the application and attempt to workaround this issue.

Again, many thanks for all your help.

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