Azure Communication CallAutomation client library for .NET - version 1.2.0

Article
05/02/2024

This package contains a C# SDK for Azure Communication Call Automation.

Getting started

Install the package

Install the Azure Communication CallAutomation client library for .NET with NuGet:

dotnet add package Azure.Communication.CallAutomation

Prerequisites

You need an Azure subscription and a Communication Service Resource to use this package.

To create a new Communication Service, you can use the Azure Portal, the Azure PowerShell, or the .NET management client library.

Key concepts

CallAutomationClient provides the functionality to answer incoming call or initialize an outbound call.

Using statements

using Azure.Communication.CallAutomation;

Authenticate the client

Call Automation client can be authenticated using the connection string acquired from an Azure Communication Resource in the Azure Portal.

var connectionString = "<connection_string>"; // Find your Communication Services resource in the Azure portal
CallAutomationClient callAutomationClient = new CallAutomationClient(connectionString);

Or alternatively using a valid Active Directory token.

var endpoint = new Uri("https://my-resource.communication.azure.com");
TokenCredential tokenCredential = new DefaultAzureCredential();
var client = new CallAutomationClient(endpoint, tokenCredential);

Examples

Make a call to a phone number recipient

To make an outbound call, call the CreateCall or CreateCallAsync function from the CallAutomationClient.

CallInvite callInvite = new CallInvite(
    new PhoneNumberIdentifier("<targets-phone-number>"),
    new PhoneNumberIdentifier("<caller-id-phonenumber>")
    );  // E.164 formatted recipient phone number

// create call with above invitation
createCallResult = await callAutomationClient.CreateCallAsync(
    callInvite,
    new Uri("<YOUR-CALLBACK-URL>")
    );

Console.WriteLine($"Call connection id: {createCallResult.CallConnectionProperties.CallConnectionId}");

Handle Mid-Connection callback events

Your app will receive mid-connection callback events via the callbackEndpoint you provided. You will need to write event handler controller to receive the events and direct your app flow based on your business logic.

/// <summary>
/// Handle call back events.
/// </summary>>
[HttpPost]
[Route("/CallBackEvent")]
public IActionResult OnMidConnectionCallBackEvent([FromBody] CloudEvent[] events)
{
    try
    {
        if (events != null)
        {
            // Helper function to parse CloudEvent to a CallAutomation event.
            CallAutomationEventData callBackEvent = CallAutomationEventParser.Parse(events.FirstOrDefault());

            switch (callBackEvent)
            {
                case CallConnected ev:
                    # logic to handle a CallConnected event
                    break;
                case CallDisconnected ev:
                    # logic to handle a CallDisConnected event
                    break;
                case ParticipantsUpdated ev:
                    # cast the event into a ParticipantUpdated event and do something with it. Eg. iterate through the participants
                    ParticipantsUpdated updatedEvent = (ParticipantsUpdated)ev;
                    break;
                case AddParticipantsSucceeded ev:
                    # logic to handle an AddParticipantsSucceeded event
                    break;
                case AddParticipantsFailed ev:
                    # logic to handle an AddParticipantsFailed event
                    break;
                case CallTransferAccepted ev:
                    # logic to handle CallTransferAccepted event
                    break;
                case CallTransferFailed ev:
                    # logic to handle CallTransferFailed event
                    break;
                default:
                    break;
            }
        }
    }
    catch (Exception ex)
    {
        // handle exception
    }
    return Ok();
}

Handle Mid-Connection events with CallAutomation's EventProcessor

To easily handle mid-connection events, Call Automation's SDK provides easier way to handle these events. Take a look at CallAutomationEventProcessor. this will ensure correlation between call and events more easily.

[HttpPost]
[Route("/CallBackEvent")]
public IActionResult OnMidConnectionCallBackEvent([FromBody] CloudEvent[] events)
{
    try
    {
        // process incoming event for EventProcessor
        _callAutomationClient.GetEventProcessor().ProcessEvents(cloudEvents);
    }
    catch (Exception ex)
    {
        // handle exception
    }
    return Ok();
}

ProcessEvents is required for EventProcessor to work. After event is being consumed by EventProcessor, you can start using its feature.

See below for example: where you are making a call with CreateCall, and wait for CallConnected event of the call.

CallInvite callInvite = new CallInvite(
    new PhoneNumberIdentifier("<targets-phone-number>"),
    new PhoneNumberIdentifier("<caller-id-phonenumber>")
    );  // E.164 formatted recipient phone number

// create call with above invitation
createCallResult = await callAutomationClient.CreateCallAsync(
    callInvite,
    new Uri("<YOUR-CALLBACK-URL>")
    );

// giving 30 seconds timeout for call reciever to answer
CancellationTokenSource cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
CancellationToken token = cts.Token;

try
{
    // this will wait until CreateCall is completed or Timesout!
    CreateCallEventResult eventResult = await createCallResult.WaitForEventAsync(token);

    // Once this is recieved, you know the call is now connected.
    CallConnected returnedEvent = eventResult.SuccessEvent;

    // ...Do more actions, such as Play or AddParticipant, since the call is established...
}
catch (OperationCanceledException ex)
{
    // Timeout exception happend!
    // Call likely was never answered.
}

If cancellation token was not passed with timeout, the default timeout is 4 minutes.

Troubleshooting

A RequestFailedException is thrown as a service response for any unsuccessful requests. The exception contains information about what response code was returned from the service.

Next steps

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit cla.microsoft.com.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

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