receiveevent.cs

[Function("HandleCallEventFunction")]
public async Task<HandleEventResponseModel> HandleEvent(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "handle/event")] HttpRequestData request)
{
    var requestBody = await new StreamReader(request.Body).ReadToEndAsync();
    var cloudEvents = CloudEvent.ParseMany(BinaryData.FromString(requestBody), skipValidation: true).ToList();
    dynamic document = null;
    foreach (var cloudEvent in cloudEvents)
    {
        var parsedEvent = CallAutomationEventParser.Parse(cloudEvent);
        _logger.LogInformation($"Received event of type {cloudEvent.Type} with call connection id {parsedEvent.CallConnectionId}");

        var callConnection = _callAutomationClient.GetCallConnection(parsedEvent.CallConnectionId);
        var callMedia = callConnection.GetCallMedia();

        if (parsedEvent is CallConnected callConnected)
        {
            var playSource = new TextSource($"You are connected - Id: {callConnected.CallConnectionId}")
            {
                SourceLocale = "en-US",
                CustomVoiceEndpointId = _configuration["CustomVoiceEndpointId"],
                VoiceName = _configuration["NeuralVoiceName"]
            };


            await callMedia.PlayToAllAsync(playSource);
            document = new
            {
                id = Guid.NewGuid().ToString(),
                callConnection.CallConnectionId,
                CallState = "Answered"
            };
        }
    }

    return new HandleEventResponseModel
    {
        Result = request.CreateResponse(HttpStatusCode.OK),
        Document = document
    };
}