This new external group chat feature enables your users to initiate and participate in group Teams chats with users from outside your organization, AAD identity required. Expanding on the existing ability for Teams users to find, participate in 1:1 chat, call and set up meetings with external users, external group chat in Teams supports up to 250 participants across multiple organizations in a single chat. This is rolling out on Teams desktop, web and mobile.
External group chat is part of Microsoft Teams Connect. Azure Active Directory (AAD) is required. The organizations are required to use the open federation policy or be on each other’s allow list.
We will begin rolling this out in mid-May and expect to complete rollout late July.
How this will affect your organization
Once your organization is federated with another organization, users can initiate a chat in the same way they would with someone inside their organization. Simply tap on the new Chat icon, enter the email address of the recipient, and tap the Search externally option to find the user. You can add up to 250 participants to a single group chat.
This rollout of external group chats will not change any previous organizational settings. All legacy settings will be honored.
What you need to do to prepare
Open federation is the default setting in Teams. If you wish to limit the organizations your users can contact or can be contacted by, and the groups and users that can participate, you can manage the allowed or blocked domains and users lists from the Teams Admin Center.