Quick Example

var io = require('socket.io-client');

var host = "https://CHANGEME";
var accessToken = "CHANGEME";

var deviceId = "CHANGEME"; 
var instanceId = "CHANGEME"; 

var serviceEndpoint = "/uapi/ws/" + deviceId + "/"+ instanceId;

//for self signed SSL certificate  

process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

var socket = io.connect(host, {
    query: "access_token=" + accessToken,
    transports: ['websocket'],
    path: serviceEndpoint
});
socket.on('connect', function(data){
    console.log('connected !\nwaiting for messages...');
});
socket.on('message', function (data) {
        var output= "[" + data.timestamp + "]\n Context: "+data.content.context+"\n Event: "+data.content.event+"\n FromApp: "+data.content.fromApp  ;
       if(data.content.context=="sys.un"){
                output += '\n';
                output+=" Category: "+ data.content.category + '\n';
                output+=" Event: "+ data.content.event + '\n';
                output+=" Action: "+ data.content.action + '\n';
                output+=" Important: "+ data.content.important + '\n';
        }
        if(data.content.context=="sys.phonecall"){
                output += '\n';
                output+=" Status: "+ data.content.payload.status + '\n';
                output+=" phoneCallId: "+ data.content.payload.phoneCallId +'\n';
                output+=" phoneCallViewId: "+ data.content.payload.phoneCallViewId+'\n';
                output+=" Extesion/DID: " + JSON.stringify(data.content.payload.extension)+'\n' ;
                if (data.content.payload.flow=="outgoing") {
                    output+=" Dialed: "+ data.content.payload.dialed+'\n';
                }
                if (data.content.payload.flow=="incoming") {
                    output+=" CalerId: "+ JSON.stringify(data.content.payload.callerid)+'\n';
                }
                output+=" Answered: " + data.content.payload.answered +'\n';
                output+=" Started: " + data.content.payload.started +'\n';
                output+=" Recorded: " + data.content.payload.recorded+'\n' ;
                if (data.content.payload.status!="destroyed"){
                    output+=" Flow: " + data.content.payload.flow+'\n';
                }
                if (data.content.payload.disposition){
                    output+=" Disposition: " + data.content.payload.disposition+'\n';
                }
                if (data.content.payload.hold=="on") {
                    output+=" Hold: " + data.content.payload.hold +'\n';
                }
                if (data.content.payload.parcked=="on") {
                    output+=" Parcked: " + data.content.payload.parcked +'\n';
                }
        }
        if(data.content.context=="sys.extension"){
            if(data.content.event=="register"){
                output += '\n';
                output+=" Extension: "+ data.content.payload.extensionNumber + '\n';
                output+=" Expire: "+ data.content.payload.registerExpire +'\n';
                output+=" FromIp: "+ data.content.payload.deviceIP+'\n';
            }
            if(data.content.event=="create"){
                output += '\n';
                output+=" Alias: "+ data.content.payload.alias + '\n';
                output+=" ExtensionId: "+ data.content.payload.extensionId +'\n';
                output+=" Agent: "+ data.content.payload.agentDevice+'\n';
                output+=" Preferred: "+ data.content.payload.preferred+'\n';
                if (data.content.payload.recActive){
                        output+=" RecState: "+ data.content.payload.recActive+'\n';
                }
                if (data.content.payload.voicemailActive){
                    output+=" Voicemail: "+ data.content.payload.voicemailActive+'\n';
                }
            }
            if(data.content.event=="update"){
                output += '\n';
                output+=" Alias: "+ data.content.payload.alias + '\n';
                output+=" ExtensionId: "+ data.content.payload.extensionId +'\n';
                output+=" Agent: "+ data.content.payload.agentDevice+'\n';
                output+=" Preferred: "+ data.content.payload.preferred+'\n';
                if (data.content.payload.recActive){
                        output+=" RecState: "+ data.content.payload.recActive+'\n';
                }
                if (data.content.payload.voicemailActive){
                    output+=" Voicemail: "+ data.content.payload.voicemailActive+'\n';
                }
            }
            if(data.content.event=="delete"){
                output += '\n';
                output+=" Removed Extension Ids: "+ JSON.stringify(data.content.payload.extensionIds) +'\n';
            }

        }

        console.log(output);
  });
socket.on('disconnect', function(){
    console.log('disconnected');
});
socket.on('error', function(err) {
    console.log('error: ' + err);
});