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

![Logo of a phone with 'Dial Home' and 'The Extra-Terrestrial Phone Home Service'.](https://docs-resources.prod.twilio.com/3d12c38e81044caff67625bc678e07a0bef359fa5e60904079e51a493d42d25c.png)

This [ASP.NET MVC](https://www.asp.net/mvc) sample application is modeled after a typical call center experience with an [IVR](https://www.twilio.com/use-cases/solutions/ivr), but with more [Reese's Pieces](https://en.wikipedia.org/wiki/Reese%27s_Pieces#ET:_The_Extra-).

Stranded aliens can call a phone number and receive instructions on how to get out of earth safely, or call their [home planet](https://bit.ly/asogi) 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](https://github.com/TwilioDevEd/ivr-phone-tree-csharp).

*[Read how Livestream](https://customers.twilio.com/906/livestream/) and [others](https://customers.twilio.com/?q=use_cases_applied\&c=CQAA) built IVR with Twilio. Also, find sample code for many web languages and frameworks on our [IVR application page](/docs/voice/interactive-voice-response).*

## 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](https://www.twilio.com/login?g=%2Fconsole%2Fphone-numbers%2Fincoming%3F\&t=98a31204d675661e83d6f3d24078fc1b9f3d6c8f85f0695f6c24ccb513fd05cf) and configure the Voice URL to point to our app. In our code the route will be `/ivr/welcome`.

![Twilio console showing IVR webhook configuration for phone number with HTTP POST method.](https://docs-resources.prod.twilio.com/92fe3569695f645baff545fe291e03587fce2919b2cc501dce7254c16f40e152.png)

If you don't already have a server configured to use as your webhook, [ngrok](https://www.twilio.com/blog/test-your-webhooks-locally-with-ngrok.html) 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](/docs/voice/twiml) to this controller on any incoming voice calls. Our app responds with [TwiML](/docs/voice/twiml) to tell Twilio what to do in response to the message.

In this case we tell Twilio to [`Gather`](/docs/voice/twiml/gather) the input from the caller and we [`Say`](/docs/voice/twiml/say) a welcome message.

```cs title="Respond with TwiML to gather an option from the caller" description="IVRPhoneTree.Web/Controllers/IVRController.cs"
// !mark(16:28)
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;
using Twilio.TwiML.Voice;

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.ActionUri("Show", "Menu"), numDigits: 1);
            gather.Say("Thank you for calling the E.T. Phone Home Service - the " +
                       "adventurous alien's first choice in intergalactic travel. " +
                       "Press 1 for directions, press 2 to make a call.");
            response.Append(gather);

            return TwiML(response);
        }
    }
}
```

After reading the text to the caller and retrieving their input, Twilio will send this input to our application.

## Where to send the caller's input

The *gather's* [`action`](/docs/voice/twiml/gather) 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 occurring after a `<Gather>` are unreachable, unless the caller enters no digits.

```cs title="Send caller input to the intended route" description="IVRPhoneTree.Web/Controllers/IVRController.cs"
// !mark(20)
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;
using Twilio.TwiML.Voice;

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.ActionUri("Show", "Menu"), numDigits: 1);
            gather.Say("Thank you for calling the E.T. Phone Home Service - the " +
                       "adventurous alien's first choice in intergalactic travel. " +
                       "Press 1 for directions, press 2 to make a call.");
            response.Append(gather);

            return TwiML(response);
        }
    }
}
```

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`](/docs/voice/twiml/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`](/docs/voice/twiml/redirect) to the main menu.

```cs title="Main menu and return instructions" description="IVRPhoneTree.Web/Controllers/MenuController.cs"
// !mark(10:41)
using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;
using Twilio.TwiML.Voice;

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: Say.VoiceEnum.PollyAmy, language: "en-GB");

            response.Say("Thank you for calling the E.T. Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel. Good bye.");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.ActionUri("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: Say.VoiceEnum.PollyAmy, language: "en-GB", loop: 3);
            response.Append(gather);

            return TwiML(response);
        }
    }
}
```

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.

```cs title="Collect more input from the caller via the Planet Directory" description="IVRPhoneTree.Web/Controllers/MenuController.cs"
// !mark(43:54)
using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Twilio.AspNet.Mvc;
using Twilio.TwiML;
using Twilio.TwiML.Voice;

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: Say.VoiceEnum.PollyAmy, language: "en-GB");

            response.Say("Thank you for calling the E.T. Phone Home Service - the " +
                         "adventurous alien's first choice in intergalactic travel. Good bye.");

            response.Hangup();

            return TwiML(response);
        }

        private TwiMLResult Planets()
        {
            var response = new VoiceResponse();
            var gather = new Gather(action: Url.ActionUri("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: Say.VoiceEnum.PollyAmy, language: "en-GB", loop: 3);
            response.Append(gather);

            return TwiML(response);
        }
    }
}
```

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`](/docs/voice/twiml/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.

```cs title="Connect to another number based on caller input" description="IVRPhoneTree.Web/Controllers/PhoneExchangeController.cs"
// !mark(9:31)
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", "+19295566487"},
                {"3", "+17262043675"},
                {"4", "+16513582243"}
            };

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

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

            return TwiML(response);
        }
    }
}
```

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](https://www.twilio.com/blog/automated-survey-csharp-aspnet-mvc)**

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](https://www.twilio.com/blog/call-tracking-csharp-aspnet-mvc)**

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