How to enable all chat in lobby

[`esborne]

I was a lobby master, and i would to make all player mic is enable when the game has started, do not care if the enemy hear our voice. But i cannot setting the all chat in the lobby, and my friend told me that i can setting all chat in the lobby with console.. But i dont know to command the all chat setting.
May you know how to enable all chat with mic in both team can hear the voice