Activities.cs

[FunctionName("TwilioHandler")]
public static async Task<HttpResponseMessage> Webhook(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "TwilioHandler/{id}")]
    HttpRequestMessage req,
    [OrchestrationClient] DurableOrchestrationClient client,
    [Table(MessageMapping.TableName, "Sms", "{id}")] MessageMapping mapping,
    ILogger log)
{
    var content = await req.Content.ReadAsStringAsync();
    var formBody = ParseForm(content);
    var status = formBody["SmsStatus"];

    if (status == "delivered" || status == "failed")
    {
        await client.RaiseEventAsync(mapping.OrchestrationId, "TwilioCallback", status);
    }

    var response = req.CreateResponse(HttpStatusCode.OK);
    response.Content = new StringContent("OK", Encoding.UTF8, "text/xml");
    return response;
}