How to implement Push To Talk in Voice+Fusion?

As described in the title, I need a reliable way to control the ability to block the outgoing audio stream.

I didn't find how to do this, so I quickly implemented a RPC message that disables / enables the desired sound source for other players .. but this does not affect the audio stream.

But user needs a guarantee that his audio will not be transmitted anywhere until he turns on the appropriate in-game indicator.