Voicemail Transcription Using .NET

    Overview

    This guide shows how to transcribe voicemail and send the transcription via SMS.

    Prerequisites

    To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. You must have a voice- and SMS-enabled Plivo phone number to receive calls and send SMS messages; you can rent numbers from the Numbers page of the Plivo console, or by using the Numbers API. If this is your first time using Plivo APIs, follow our instructions to set up a .NET development environment and a web server and safely expose that server to the internet.

    Create an MVC controller to implement voicemail transcription

    In Visual Studio, create a controller called VoicemailController.cs and paste into it this code.

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    using System;
    using Plivo;
    using System.Collections.Generic;
    using Microsoft.AspNetCore.Mvc;
    
    namespace VoiceApp.Controllers
    {
        public class Voicemail : Controller
        {
            public IActionResult Index()
            {
                var hostName = Request.HttpContext.Request.Host.Value;
                Plivo.XML.Response resp = new Plivo.XML.Response();
                resp.AddSpeak("Please leave a message. Press the star key when you're done",
                    new Dictionary<string, string>() { });
                resp.AddRecord(new Dictionary<string, string>() {
                    {"transcriptionType","auto" },
                    {"transcriptionUrl","https://" + hostName + "/Voicemail/TranscriptionUrl/" },
                    {"action", "https://" + hostName + "/Voicemail/ActionUrl/"},
                    {"finishOnKey", "*"},
                    {"maxLength", "20"},
                });
                resp.AddSpeak("Recording not received",
                    new Dictionary<string, string>() { });
                var output = resp.ToString();
                return this.Content(output, "text/xml");
            }
    
            public IActionResult ActionUrl()
            {
                
                Console.WriteLine(Request.Form);
                return this.Content("OK");
            }
            public IActionResult TranscriptionUrl()
            {
        
                Console.WriteLine(Request.Form);
                var api = new PlivoApi("<auth_id>", "<auth_token>");
                var response = api.Message.Create(
                    src: "<sender_id>",
                    dst: new List<String> { "<destination_number>" },
                    text: "You have a new transcription: "+ Request.Form["transcription"]
                    );
                Console.WriteLine(response);
        
                return this.Content("OK");
            }
        }
    }
    

    Save the file. Edit Properties/launchSettings.json and set the applicationUrl.

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

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

    Create a Plivo application for voicemail transcription

    Associate the MVC controller you created with Plivo by creating a Plivo application. Visit Voice > Applications in the Plivo console and click on Add New Application, or use Plivo’s Application API.

    Give your application a name — we called ours Voicemail-Transcription. Enter the server URL you want to use (for example https://<yourdomain>.com/voicemail/) in the Answer URL field and set the method to POST. Click Create Application to save your application.

    Plivo Create Application Voicemail Transcription

    Assign a Plivo number to your application

    Navigate to the Numbers page and select the phone number you want to use for this application.

    From the Application Type drop-down, select XML Application.

    From the Plivo Application drop-down, select Voicemail-Transcription (the name we gave the application).

    Click Update Number to save.

    Assign Voicemail Application

    Test

    Make a call to your Plivo number and leave yourself a voicemail message. You should receive a text message with the transcription.

    Note: If you’re using a Plivo Trial account, you can send SMS messages 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.