Make Outbound Calls Using .NET

    Overview

    This guide shows how to make an outgoing call and greet the call recipient with a text-to-speech message when they answer. Use cases such as voice notifications and alerts, voice surveys, and, voice one-time passwords involve outbound calls as part of their call flow.

    You can start making and receiving calls either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below.

    You can create and deploy a PHLO to make an outbound call with a few clicks on the PHLO canvas, and trigger it with some simple code.

    How it works

    Outbound- Call Flow

    Prerequisites

    To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. If this is your first PHLO, follow our instructions to set up a .NET development environment.

    Create the PHLO

    To create a PHLO, visit the PHLO page of the Plivo console. If this is your first PHLO, the PHLO page will be empty.

    Create a PHLO for outbound calls

    • Click Create New PHLO.

    • In the Choose your use case pop-up, click Build my own. The PHLO canvas will appear with the Start node.
      Note: The Start node is the starting point of any PHLO. It lets you trigger a PHLO to start upon one of three actions: incoming SMS message, incoming call, or API request.
    • From the list of components on the left side, drag and drop the Initiate Call component onto the canvas. When a component is placed on the canvas it becomes a node.

    • Draw a line to connect the Start node’s API Request trigger state to the Initiate Call node.

    • In the Configuration pane at the right of the canvas, configure the Initiate Call node with a caller ID in the From field. Enter the destination number you wish to call in the To field.

      Note: You can define a static payload by specifying values when you create the PHLO, or define a dynamic payload by passing values through Liquid templating parameters when you trigger the PHLO from your application.
    • Once you’ve configured the node, click Validate to save the configuration.

    • Similarly, create a node from the Play Audio component. Connect the Initiate Call node to the Play Audio node using the Answered trigger state.

    • Configure the Play Audio node to play a message to the user by entering text in the Speak Text box in the Prompt section of the Configuration pane — for example, “Hello, you just received your first call.”

    • Connect the Initiate Call node’s Answered trigger state to the Play Audio node.

    • After you complete the configuration, give the PHLO a name by clicking in the upper left, then click Save.

    Your PHLO is now ready to test.

    Trigger the PHLO

    You integrate a PHLO into your application workflow by making an API request to trigger the PHLO with the required payload — the set of parameters you pass to the PHLO. You can define a static payload by specifying values when you create the PHLO, or define a dynamic payload by passing values through parameters when you trigger the PHLO from your application.

    In either case, you need your Auth ID and Auth Token, which you can get from the overview page of the Plivo console.

    AUTHID

    You also need the PHLO ID, which you can copy from the PHLO list page.

    PHLO List

    With a static payload

    When you configure values when creating the PHLO, they act as a static payload.

    With Static Payload

    Code

    In Visual Studio, in the CS project, open the file Program.cs and paste into it this code.

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    
    using System;
    using Plivo;
    
    namespace test_PHLO
    {
        class Program
        {
            public static void Main(string[] args)
            {
                var phloClient = new PhloApi("<auth_id>", "<auth_token>"); 
                var phloID = "<phlo_id>"; 
                var phlo = phloClient.Phlo.Get(phloID);
                Console.WriteLine(phlo.Run());
            }
        }
    }
    

    Replace the auth placeholders with your authentication credentials from the Plivo console. Replace the phlo_id placeholder with your PHLO ID from the Plivo console.

    With a dynamic payload

    To use dynamic values for the parameters, use Liquid templating parameters when you create the PHLO and pass the values from your code when you trigger it.

    With Dynamic Payload

    Code

    In Visual Studio, in the CS project, open the file Program.cs and paste into it this code.

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    
    using System;
    using System.Collections.Generic;
    using Plivo;
    
    namespace test_PHLO
    {
        class Program
        {
            public static void Main(string[] args)
            {
                var phloClient = new PhloApi("<auth_id>", "<auth_token>"); 
                var phloID = "<phlo_id>"; 
                var phlo = phloClient.Phlo.Get(phloID); 
                var data = new Dictionary<string, object>
                {
                    { "from", "<caller_id>" },
                    { "to", "<destination_number>" }
    
                };  
                Console.WriteLine(phlo.Run(data));
            }
        }
    }
    

    Replace the auth placeholders with your authentication credentials from the Plivo console. Replace the phlo_id placeholder with your PHLO ID from the Plivo console. Replace the phone number placeholders with actual phone numbers in E.164 format (for example, +12025551234).

    Test

    Save the file and run it.

    Note: If you’re using a Plivo Trial account, you can make calls only to phone numbers that have been verified with Plivo. You can verify (sandbox) a number by going to the console’s Phone Numbers > Sandbox Numbers page.

    To make your first outbound call in the traditional API/XML way, you can refer to the instructions in the below section to begin your implementation.

    Outline

    Outbound- Call Flow

    Implementation

    In this section, we will guide you in setting up an app using Plivo’s API/XML to make your first outbound call. First, let’s make sure you meet these prerequisites before we dive into the code.

    Prerequisites

    This section will guide you through how to use Plivo APIs to make voice calls from your application. First, let’s make sure you meet these prerequisites before we dive into the code.

    • Plivo Auth Id and Auth Token: You will find your Plivo Auth Id and Auth Token on the home screen of your Plivo Console. Click here to sign-up for a Plivo account if you haven’t already!

      Find Your Auth Credentials on Plivo Console

    • Plivo Phone Number(Optional): You can purchase numbers from the Numbers section of your Plivo Console and use the same as the caller ID for the outbound call. This number will also help you receive incoming calls as you must have a voice-enabled Plivo phone number to do the same. Please note that you can also purchase numbers using the Numbers API.

      Buy a New Plivo Number

    • Answer Url: When a call is answered by the destination_number, you can control the call flow with the help of the answer_url set in the API request. Plivo will invoke the answer_url specified as soon as the call is answered and expect a valid XML response with instructions to handle the call. For example, you can use https://s3.amazonaws.com/static.plivo.com/answer.xml as answer_url to test your first outgoing call. The XML response of this is:

      <Response> 
      <Speak>Congratulations! You've made your first outbound call!</Speak> 
      </Response>
      

      As you can tell, the XML above holds instructions to say ‘Congratulations! You’ve made your first outbound call!’ to the callee. You can find the entire list of Plivo XML verbs and their details in the XML Reference section of the website here.

    Set up Your Dotnet Dev Environment

    You must set up and install Dotnet Framework(.NET Framework 4.6 or higher) and Plivo’s Dotnet SDK to make your first call. Here’s how.

    Install Dotnet Framework

    Operating SystemInstructions
    macOS & LinuxYou would already have Dotnet Framework installed, you can check this by running the command dotnet --version in the terminal. If you do not have it installed, you can install it from here.
    WindowsTo install Dotnet Framework on Windows you can follow the instructions from here.

    Install Plivo .NET Nuget Package using Visual Studio

    • Create a new project in Visual Studio

      Create New Project

    • Choose a Template for the new project

      Choose Template

    • Install the Plivo Nuget package

      Manage Nuget packages Select Plivo Nuget package

    Create the Outbound Call App

    Once you have the above prerequisites set, You can follow the below instructions to create an app to make an outbound call and leave a text-to-speech message once the call recipient answers the call.

    Now, open the file in the CS project called Program.cs and paste the below code.

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    
    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> { "+14157654321" },
                    from: "+14151234567",
                    answerMethod: "GET",
                    answerUrl: "http://s3.amazonaws.com/static.plivo.com/answer.xml"
                );
                Console.WriteLine(response);
            }
        }
    }
    
    Note:
    • Replace the placeholders auth_id & auth_token with your credentials from Plivo Console.
    • We recommend that you store your credentials in the auth_id & auth_token environment variables, so as to avoid the possibility of accidentally committing them to source control. If you do this, you can initialize the client with no arguments and it will automatically fetch them from the environment variables
    • You can use Environment.SetEnvironmentVariable Method to store environment variables and fetch them using Environment.GetEnvironmentVariable Method while initializing the client.
    • Replace the placeholder +14151234567 with the Phone number which you have purchased and +14157654321 with the phone number you will be making calls to.
    • Both plivo_source_number and +14157654321 should be in E.164 format

    Test and Validate

    Once you have created the Outbound Call App, Save the file and run it.

    Make outbound call

    Note: If you are using a Plivo Trial account for this example, you can only make calls to phone numbers that have been verified with Plivo. Phone numbers can be verified at the Sandbox Numbers page.