VOIP high latency

Hello!
I am using null online subsystem and enable voice

My DefaultEngine.ini

[Voice]
 bEnabled=true
    
[OnlineSubsystem]
bHasVoiceEnabled=true
DefaultPlatformService=Null

My DefaultGame.ini

[/Script/Engine.GameSession]
bRequiresPushToTalk=True

But voice latency is about 1-1.5 sec. What is the problem? Help me, please.