Hi, @Chakravarthi T ,
From official document, Microsoft Graph must send chatMessage in a channel or a chat. And I think SignalR is a better choice for the boardcast requirement.
The SignalR Hubs API enables you to call methods on connected clients from the server. In the server code, you define methods that are called by client. In the client code, you define methods that are called from the server. SignalR takes care of everything behind the scenes that makes real-time client-to-server and server-to-client communications possible.
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