I have been thinking about a way to do communication without teamspeak and thought about a number of ways to do it,
some ways would be
via voice and chat channely deicated to local area, groups, factions, global (system), galaxy/universe wide
the second way would be allowing you to create completly custom chatrooms both for typing and voice chat (like teampspeak where you can create extra rooms on a server
another possibility would be a basic chat completly used via chat commands (minecraft chat/stellaris chat)
the last and in my opinion best way would be to do it like the "acre" (advance combar radio enviorment) mod for arma, creating a itam that allows you to join specific frequencies and even using speciall encoding procedures to avoid being spied on, this would allow for a great diversity of gameplay from factions using multiple frequencies to have a strictly organised comm system, for example group a has 2 comm officers a and b, a is responsible for commands from the higher ups and relaying them to the group leader, b responsible for leading orders further down the command chain.
Or a radio station opening on a frequencie broadcasting news and playing music all COMPLETELY player driven.
Basic functions of acre demonstrated:
wow ingore this while i edit it