HomeController.cs

using System;
using System.Globalization;
using System.Linq;
using System.Web.Mvc;
using Twilio;
using Twilio.TwiML;
using Twilio.TwiML.Mvc;

namespace TwilioBaseApp.Controllers
{

    // PROMO
    public class HomeController : TwilioController
    {
        // http://your_ngrok_url/SayHello
        // Message
        public ActionResult SayHello()
        {
            var twiml = new TwilioResponse();
            return TwiML(twiml.Message("Thanks for coming in here's some <3 MKNET"));
        }

        // http://your_ngrok_url/Answer
        public ActionResult Answer()
        {
            var twiml = new TwilioResponse();
            return TwiML(twiml.DialConference("party room"));
            //return TwiML(twiml.Say("Congratulations! You've just won a cool gift"));
        }

        // Get all telephone numbers (Distinct) & Initiate Call
        public void CallBack()
        {
            var client = new TwilioRestClient(St.AccountSid, St.AuthToken);

            var numbers = client.ListMessages("your_twilio_number").Messages.Select(m => m.From).Distinct();

            foreach (var number in numbers)
            {
                client.InitiateOutboundCall("+your_twilio_number", number, "http://your_ngrok_url/Answer");
            }
        }
    }
}