@Huy Hoàng Phan , To benefit the community summarizing our discussions from comments
We do not currently support exchanging messages between peers in a group call.
Once potential suggestion is to use ACS Chat SDK side by side with Calling, and exchange messages via that channel.
-We discussed on this with our product engineering team internally- (thanks for creating the GitHub feedback item)
Those are custom events (custom messages) as you mentioned, our product team is looking at adding such custom event in the near future. However, there is no ETA at this time. As soon as we have more information, we will update the GitHub feedback item.
You may also checkout these links for additional info:
ACS release notes
Roadmap and current private preview features
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