IVR: Phone Tree with C# and ASP.NET MVC

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ET Phone Home

This ASP.NET MVC sample application is modeled after a typical call center experience, but with more Reese's Pieces.

Stranded aliens can call a phone number and receive instructions on how to get out of earth safely, or call their home planet directly. In this tutorial, we'll show you the key bits of code to make this work.

To run this sample app yourself, download the code and follow the instructions on GitHub.

Read how Livestream used Twilio to build custom call routing logic and IVR messages.

Respond to the Phone Call

To initiate the phone tree, we need to configure one of our Twilio numbers to send our web application an HTTP request when we get an incoming call.

Click on one of your numbers and configure the Voice URL to point to our app. In our code the route will be /ivr/welcome.

IVR Webhook Configuration

If you don't already have a server configured to use as your webhook, ngrok is a great tool for testing webhooks locally.

With our Twilio number configured, we are prepared to respond to the Twilio request.

Respond to the Twilio request with TwiML

Our Twilio number is now configured to send HTTP requests to this controller on any incoming voice calls. Our app responds with TwiML to tell Twilio what to do in response to the message.

In this case we tell Twilio to Gather the input from the caller and we Play a welcome message.

Loading Code Samples...
Language
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class IVRController : TwilioController
    {
        // GET: IVR
        public ActionResult Index()
        {
            return View();
        }

        // POST: IVR/Welcome
        [HttpPost]
        public TwiMLResult Welcome()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Show", "Menu"), numDigits: 1);
            gather.Play("http://howtodocs.s3.amazonaws.com/et-phone.mp3", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
IVRPhoneTree.Web/Controllers/IVRController.cs
Respond with TwiML to gather an option from the caller

IVRPhoneTree.Web/Controllers/IVRController.cs

After playing the audio and retrieving the caller's input, Twilio will send this input to our application.

Where to send the caller's input

The gather's action parameter takes an absolute or relative URL as a value - in our case, the /menu/show route.

When the caller has finished entering digits, Twilio will make a GET or POST request to this URL including a Digits parameter with the number our caller chose.

After making this request, Twilio will continue the current call using the TwiML received in your response. Any TwiML verbs occuring after a <Gather> are unreachable, unless the caller enters no digits.

Loading Code Samples...
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using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class IVRController : TwilioController
    {
        // GET: IVR
        public ActionResult Index()
        {
            return View();
        }

        // POST: IVR/Welcome
        [HttpPost]
        public TwiMLResult Welcome()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Show", "Menu"), numDigits: 1);
            gather.Play("http://howtodocs.s3.amazonaws.com/et-phone.mp3", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
IVRPhoneTree.Web/Controllers/IVRController.cs
Send caller input to the intended route

IVRPhoneTree.Web/Controllers/IVRController.cs

Now that we have told Twilio where to send the caller's input, we can look at how to process that input.

The Main Menu: Process the caller's selection

This route handles processing the caller's input.

If our caller chooses 1 for directions, we use the helper method ReturnInstructions to respond with TwiML that will Say directions to our caller's extraction point.

If the caller chooses 2 to call their home planet, we need to gather more input from them. We'll cover this in the next step.

If the caller enters anything else we respond with a TwiML Redirect to the main menu.

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using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class MenuController : ControllerBase
    {
        // POST: Menu/Show
        [HttpPost]
        public ActionResult Show(string digits)
        {
            var selectedOption = digits;
            var optionActions = new Dictionary<string, Func<ActionResult>>()
            {
                {"1", ReturnInstructions},
                {"2", Planets}
            };

            return optionActions.ContainsKey(selectedOption) ?
                optionActions[selectedOption]() :
                RedirectWelcome();
        }

        private TwiMLResult ReturnInstructions()
        {
            var response = new VoiceResponse();
            response.Say("To get to your extraction point, get on your bike and go down " +
                         "the street. Then Left down an alley. Avoid the police cars. Turn left " +
                         "into an unfinished housing development. Fly over the roadblock. Go " +
                         "passed the moon. Soon after you will see your mother ship.",
                         voice: "alice", language: "en-GB");

            response.Say("Thank you for calling the ET Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Interconnect", "PhoneExchange"), numDigits: 1);
            gather.Say("To call the planet Broh doe As O G, press 2. To call the planet " +
                     "DuhGo bah, press 3. To call an oober asteroid to your location, press 4. To " +
                     "go back to the main menu, press the star key ",
                     voice: "alice", language: "en-GB", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
IVRPhoneTree.Web/Controllers/MenuController.cs
Main menu and return instructions

IVRPhoneTree.Web/Controllers/MenuController.cs

That was only the main menu and the first option. If the caller chooses 2, we will take them to The Planet Directory in order to collect more input.

The Planet Directory: Collect more input from the caller

If our callers choose to call their home planet we will give them the planet directory. This is akin to a typical "company directory" feature of most IVRs.

In our TwiML response we again use a Gather verb to receive our caller's input. This time, the action verb points to the planets route, which will switch our response based on what the caller chooses.

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using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class MenuController : ControllerBase
    {
        // POST: Menu/Show
        [HttpPost]
        public ActionResult Show(string digits)
        {
            var selectedOption = digits;
            var optionActions = new Dictionary<string, Func<ActionResult>>()
            {
                {"1", ReturnInstructions},
                {"2", Planets}
            };

            return optionActions.ContainsKey(selectedOption) ?
                optionActions[selectedOption]() :
                RedirectWelcome();
        }

        private TwiMLResult ReturnInstructions()
        {
            var response = new VoiceResponse();
            response.Say("To get to your extraction point, get on your bike and go down " +
                         "the street. Then Left down an alley. Avoid the police cars. Turn left " +
                         "into an unfinished housing development. Fly over the roadblock. Go " +
                         "passed the moon. Soon after you will see your mother ship.",
                         voice: "alice", language: "en-GB");

            response.Say("Thank you for calling the ET Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Interconnect", "PhoneExchange"), numDigits: 1);
            gather.Say("To call the planet Broh doe As O G, press 2. To call the planet " +
                     "DuhGo bah, press 3. To call an oober asteroid to your location, press 4. To " +
                     "go back to the main menu, press the star key ",
                     voice: "alice", language: "en-GB", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
IVRPhoneTree.Web/Controllers/MenuController.cs
Collect more input from the caller via the Planet Directory

IVRPhoneTree.Web/Controllers/MenuController.cs

Again we show some options to the caller and instruct Twilio to collect the caller's choice.

The Planet Directory: Connect the caller to another number

In this route, we grab the caller's selection off the request and store it in a variable called userOption. We then use a Dial verb with the appropriate phone number to connect our caller to their home planet.

The current numbers are hardcoded, but they could also be read from a database or from a file.

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using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class PhoneExchangeController : ControllerBase
    {
        // POST: PhoneExchange/Interconnect
        [HttpPost]
        public ActionResult Interconnect(string digits)
        {
            var userOption = digits;
            var optionPhones = new Dictionary<string, string>
            {
                {"2", "+12024173378"},
                {"3", "+12027336386"},
                {"4", "+12027336637"}
            };

            return optionPhones.ContainsKey(userOption)
                ? Dial(optionPhones[userOption]) : RedirectWelcome();
        }

        private TwiMLResult Dial(string phoneNumber)
        {
            var response = new VoiceResponse();
            response.Dial(phoneNumber);

            return TwiML(response);
        }
    }
}
IVRPhoneTree.Web/Controllers/PhoneExchangeController.cs
Connect to another number based on caller input

IVRPhoneTree.Web/Controllers/PhoneExchangeController.cs

That's it! We've just implemented an IVR phone tree that will delight and serve your customers.

Where to Next?

If you're a C# developer working with Twilio, you might enjoy these other tutorials:

Automated Survey

Instantly collect structured data from your users with a survey conducted over a voice call or SMS text messages. Learn how to create your own survey in ASP.NET MVC.

Call Tracking

Convert web traffic into phone calls with the click of a button.

Did this help?

Thanks for checking out this tutorial! If you have any feedback to share with us, we'd love to hear it. Connect with us on Twitter and let us know what you build!

Agustin Camino
Kat King
Hector Ortega
Andrew Baker
David Prothero

Need some help?

We all do sometimes; code is hard. Get help now from our support team, or lean on the wisdom of the crowd browsing the Twilio tag on Stack Overflow.

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Loading Code Samples...
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class IVRController : TwilioController
    {
        // GET: IVR
        public ActionResult Index()
        {
            return View();
        }

        // POST: IVR/Welcome
        [HttpPost]
        public TwiMLResult Welcome()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Show", "Menu"), numDigits: 1);
            gather.Play("http://howtodocs.s3.amazonaws.com/et-phone.mp3", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class IVRController : TwilioController
    {
        // GET: IVR
        public ActionResult Index()
        {
            return View();
        }

        // POST: IVR/Welcome
        [HttpPost]
        public TwiMLResult Welcome()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Show", "Menu"), numDigits: 1);
            gather.Play("http://howtodocs.s3.amazonaws.com/et-phone.mp3", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class MenuController : ControllerBase
    {
        // POST: Menu/Show
        [HttpPost]
        public ActionResult Show(string digits)
        {
            var selectedOption = digits;
            var optionActions = new Dictionary<string, Func<ActionResult>>()
            {
                {"1", ReturnInstructions},
                {"2", Planets}
            };

            return optionActions.ContainsKey(selectedOption) ?
                optionActions[selectedOption]() :
                RedirectWelcome();
        }

        private TwiMLResult ReturnInstructions()
        {
            var response = new VoiceResponse();
            response.Say("To get to your extraction point, get on your bike and go down " +
                         "the street. Then Left down an alley. Avoid the police cars. Turn left " +
                         "into an unfinished housing development. Fly over the roadblock. Go " +
                         "passed the moon. Soon after you will see your mother ship.",
                         voice: "alice", language: "en-GB");

            response.Say("Thank you for calling the ET Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Interconnect", "PhoneExchange"), numDigits: 1);
            gather.Say("To call the planet Broh doe As O G, press 2. To call the planet " +
                     "DuhGo bah, press 3. To call an oober asteroid to your location, press 4. To " +
                     "go back to the main menu, press the star key ",
                     voice: "alice", language: "en-GB", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class MenuController : ControllerBase
    {
        // POST: Menu/Show
        [HttpPost]
        public ActionResult Show(string digits)
        {
            var selectedOption = digits;
            var optionActions = new Dictionary<string, Func<ActionResult>>()
            {
                {"1", ReturnInstructions},
                {"2", Planets}
            };

            return optionActions.ContainsKey(selectedOption) ?
                optionActions[selectedOption]() :
                RedirectWelcome();
        }

        private TwiMLResult ReturnInstructions()
        {
            var response = new VoiceResponse();
            response.Say("To get to your extraction point, get on your bike and go down " +
                         "the street. Then Left down an alley. Avoid the police cars. Turn left " +
                         "into an unfinished housing development. Fly over the roadblock. Go " +
                         "passed the moon. Soon after you will see your mother ship.",
                         voice: "alice", language: "en-GB");

            response.Say("Thank you for calling the ET Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.Action("Interconnect", "PhoneExchange"), numDigits: 1);
            gather.Say("To call the planet Broh doe As O G, press 2. To call the planet " +
                     "DuhGo bah, press 3. To call an oober asteroid to your location, press 4. To " +
                     "go back to the main menu, press the star key ",
                     voice: "alice", language: "en-GB", loop: 3);
            response.Gather(gather);

            return TwiML(response);
        }
    }
}
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;

namespace IVRPhoneTree.Web.Controllers
{
    public class PhoneExchangeController : ControllerBase
    {
        // POST: PhoneExchange/Interconnect
        [HttpPost]
        public ActionResult Interconnect(string digits)
        {
            var userOption = digits;
            var optionPhones = new Dictionary<string, string>
            {
                {"2", "+12024173378"},
                {"3", "+12027336386"},
                {"4", "+12027336637"}
            };

            return optionPhones.ContainsKey(userOption)
                ? Dial(optionPhones[userOption]) : RedirectWelcome();
        }

        private TwiMLResult Dial(string phoneNumber)
        {
            var response = new VoiceResponse();
            response.Dial(phoneNumber);

            return TwiML(response);
        }
    }
}