Set Up a .NET Dev Environment for Voice Calls

This guide shows how to set up a development environment in five minutes to trigger API requests and start serving Plivo XML to control your call flow. It also shows how to test your code using tunneling software to expose the local dev server to the public internet.

Install .NET Framework and the Plivo NuGet package

To get started, install and set up .NET Framework 4.6 or higher and Plivo’s .NET SDK.

Install the Plivo .NET SDK using Visual Studio

To install the Plivo .NET SDK:

• Create a new project in Visual Studio.

• Choose a template for the new project.

• Install the Plivo NuGet package.

Trigger an API request

Now you can create a file in the project directory and execute code to trigger any Plivo API. Here’s some example code that makes an outbound call. Open the Program.cs file in the CS project and paste into it this code.

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using System;
using System.Collections.Generic;
using Plivo;

namespace testplivo
{
    class Program
    {
        static void Main(string[] args)
        {
            var api = new PlivoApi("<auth_id>","<auth_token>");
            var response = api.Call.Create(
                to: new List<String> { "<Caller_ID>" },
                from: "<Destination_Number>",
                answerMethod: "GET",
                answerUrl: "http://s3.amazonaws.com/static.plivo.com/answer.xml"
            );
            Console.WriteLine(response);
        }
    }
}

Save the file and run it.

You can follow the same approach to trigger other API requests. Refer to our detailed API reference to see all the API requests available on the Voice API platform.

Serve an XML document and manage callbacks

When you receive a call on a Plivo voice-enabled number, you can control the call flow by declaring an Answer URL for the Plivo application associated with that phone number. Plivo will invoke the Answer URL specified and expect a valid XML response to handle the call.

In addition to requests to the Answer URL, Plivo initiates other HTTP requests to your application server based on specific XML elements in your Answer XML document. Such requests are broadly classified into two categories:

Action URL requests: These requests are typically invoked at the end of an XML element’s execution, and the server expects XML instructions to carry forward the call in response to these requests. This happens, for example, when a caller provides Touch-Tone input during GetInput XML execution.

Callback URL requests: These requests serve as webhooks to pass the application server information about events through the course of an XML element’s execution, such as when a conference participant is muted or unmuted. No XML instructions are expected in response to these requests.

Set up a .NET Framework application to serve XML and manage callbacks

Here’s how to set up a .NET Framework application to serve XML documents and manage callbacks.

• Create an MVC web app.

• Configure the MVC application and provide a project name. We called ours “Receivecall.”

• Install the Plivo NuGet package.

Create a controller to receive calls

Navigate to the Controllers directory in the Receivecall application, create a Controller named ReceivecallController.cs, and paste into it this code.

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using System;
using Plivo.XML;
using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;

namespace Receivecall
{
    public class ReceivecallController : Controller
    {
        public IActionResult Index()
        {
            Plivo.XML.Response resp = new Plivo.XML.Response();
            resp.AddSpeak("Hello, you just received your first call",
                new Dictionary<string, string>() {
        {
        "loop",
        "3"
        }
                });
            var output = resp.ToString();
            Console.WriteLine(output);

            return this.Content(output, "text/xml");
        }
    }
}

Before starting the application, edit Properties/launchSettings.json and set applicationUrl to

    "applicationUrl": "http://localhost:5000/"

Run the project and you should see your basic server application in action on http://localhost:5000/receivecall/.

Ngrok setup

To serve XML documents, your local server must connect with Plivo API services. For that, we recommend using ngrok, which exposes local servers running behind NATs and firewalls to the public internet over secure tunnels. Using ngrok, you can set webhooks that can talk to the Plivo server.

Install ngrok and run it on the command line, specifying the port that hosts the application on which you want to receive messages (5000 in this case):

./ngrok http 5000

This will start the ngrok server on your local server.

Ngrok will display a forwarding link that you can use as a webhook to access your local server over the public network. You should be able to see your basic server application in action at https://<nrgok_URL>/receive_call/.

You can follow the same approach to serve other XML documents to manage other call flows. Refer to our detailed XML reference to see all the XML elements available on the Voice API platform.