I think you’ve misunderstood again.

In my call, I left the mic open by default, and configured a key as push-to-mute.
In the game, I left the mic muted by default, and configured the same key as push-to-talk.

This way, I could speak on the call or in the game, but never both at once, and the my was not open by default in the game.

Edit: Oh, I think I figured out what your first sentence was supposed to mean. I think you’re saying that you want not only to choose between two voice chats (the game and the call) when talking, but also be muted in both by default (so other sounds in the room won’t be heard by anyone). Yes?