Rainbow incoming voice audio is mixed with present audio on PC

When there is f.e. music playing on the PC at the time of an incoming call on Rainbow :

Rainbow client receives a call = the ringtone is heard = ok

BUT when you take the call, the audio is mixed between the present audio and the Rainbow conversation.

Can this be fixed, so the first audio source is muted and only Rainbow audio is coming thru?

This is on all audio applications. I also have it in law firms where secretary is listening to a recording in order to make an  official document or report.