As i implement PortSIP iOS SDK to my application I check conference in PortSIP SDK's demo application (https://apps.apple.com/us/app/portsip-softphone/id426903818).
In application i try conference if main caller(A) call to user(B) and then main caller(A) call to user (C) and merge all that call. After merge if main caller(A) mute his call then user(B) and user(C) can't able to talk with each other. I asked same question to PortSIP support but they say that's how it's designed. So is this correct behaviour for conference call?