gistfile1.txt

    var iceServers = {
        iceServers: [{
            url: 'stun:23.21.150.121'
        }]
    };

    var optionalRtpDataChannels = {
        optional: [{DtlsSrtpKeyAgreement: true}, {RtpDataChannels: true }]
    };

        if (isFirefox) {
            offerer = new mozRTCPeerConnection(iceServers, optionalRtpDataChannels);
        }
        else {
            offerer = new webkitRTCPeerConnection(iceServers, optionalRtpDataChannels);
        }