Conference Participant Messaging

during a Confbridge conference I can see SIP MESSAGE sent to participants from Asterisk console activating SIP debug (pjsip set logger on).
My Bria Softphone respond with 200OK but I can’t see the message. Is it the expected behaviour?
Thank you

The message is a custom JSON one[1] which requires client support. It is not supported by Bria. It was written to be used by WebRTC clients.

Thank you for your clarification.