v3 has its own built-in socket.io server. It has pubnub/firebase demos as well; however reliable-signaler or socketio-over-nodejs or similar codes can NOT be used with v3. Please use
v3 can use XHR/XMPP/etc. signaling implementations as well. Please check PubNubConnection.js to see how to configure it for 3rd party signaling implementations. You simply have to modify top few lines.
RTCMultiConnection-v2 (old) videos: https://vimeo.com/muazkh