In defaultengine.ini
`[Voice]
bEnabled=true
[OnlineSubsystem]
bHasVoiceEnabled=true`
Is all that is needed
Default Game.ini then has
[/Script/Engine.GameSession] bRequiresPushToTalk=true
to turn on push to talk or not. The plugin isn’t required at all for voice, but StopNetworkedVoice and StartNetworkedVoice can be used for PTT. There are also console commands that do the same thing though.