To establish a P2P connection without a signalling server you have to exchange the SDPs between your clients (local and remote). Try it out. Open the demo in two tabs or two different devices, lets say client A and client B.
createOfferRemoteanswer button (this will generate another SDP and add it to text box Local)Local) and send it to A (e.g. using email)Remoteanswer button
Now you should be able to see P2P connection working.