Anuj Sharma worst is a bit harsh, to me they are pretty clear and simple.
So what you want to accomplish ? a voip system ? centralized, decentralized ? a service where you can leave messages ? what is the scope ? what do you need ?
So I am making a chat app with firebase and also use a node server for sending otp to register mobile users. And i want to make a functionality of one to one audio call using webrtc. thats it. again lots of thanks.