• A Twilio account and active number. If you don’t have an account, go ahead and create one now.
• If you want transcribed voicemails sent to you via email, you’ll also need a Twilio SendGrid account, with a verified sender.

Verified Sender

Configure

1. Open up your Twilio console and head to the Functions overview section.
2. Under Overview, click the blue “Create Service” button.
3. Give it the service name, “OutsmartingVoiceMail”
4. Under Settings -> Environment Variables, add a new environment variable called SENDGRID_API_SECRET, paste in your API Key Secret (begins with SG) you saved from the step above, then click Add.
   
   We also need to create environment variables for the email addresses you’ll be sending to and from.
5. Create a TO_EMAIL_ADDRESS variable, enter the email to receive your voicemails, then click “Add”.
6. Create the variable FROM_EMAIL_ADDRESS, enter one of the verified sender emails in your SendGrid account, then click Add. It’s best to use two of your personal emails when testing. Emails from a company domain (e.g. @twilio.com) will be blocked if not verified properly.

1. Add `@sendgrid/mail` and the version 7.2.5, then click Add.

Forward Voicemail via Email

1. At the top left of the screen, click the blue “Add” + button and select “Add Function”. You can leave the Function at the default, “Protected”. Protected means that only requests from your account with the proper X-Twilio-Signature can successfully execute the Function.
2. Add a name and path for your Function, I used /forwardVMViaEmail.

1. The Function is included below. Feel free to copy, paste, and save. If you'd like to understand what's happening, read on.

//Initialize SendGrid Mail Client const sgMail = require('@sendgrid/mail');  // Define Handler function required for all Twilio Functions exports.handler = function(context, event, callback) {  // Build SG mail request sgMail.setApiKey(context.SENDGRID_API_SECRET);  // Define message params  const msg = {  to: context.TO_EMAIL_ADDRESS,  from: context.FROM_EMAIL_ADDRESS,  html: `<p><strong>New Voicemail from:</strong> ${event.From}</p>  <strong>Transcription is:</strong><br>${event.TranscriptionText}<p><a href=${event.RecordingUrl}>  Click here to Listen to the Recording</a></p>`,  subject: `New Voicemail from: ${event.From}`,  };  // Send message  sgMail.send(msg)  .then(response => {  console.log("Neat.")  return callback();  })  .catch(err => {  console.log("Not neat.")  return callback(err);  }); }; 

How your Function works

1. At the top of your Function, we initialize the @sendgrid/mail module which will help us craft a mail request to SendGrid.
2. We then call Twilio's handler function, which is required for all Twilio Functions. For more information about how the handler function works and what the context, event, and callback arguments are used for, check out the docs here.
3. Next, we build the SendGrid request per the guidelines in the docs here.
4. Since Twilio Functions are written in JavaScript, we use the SendGrid Node.js library.
5. The first thing we do when building our request is use the setApiKey() method which will authenticate our request. Inside it, we place our API Secret, which we pull from the Function context.
6. Next, we build our message parameters. Again, we pull our to and from emails from context, and we also reference a couple variables, url and From, from the event argument of our Function.
7. Finally, we call the send() method to send the request to SendGrid for delivery. Inside the promise handler, we print a message to let us know the request was accepted, then we embed our empty Function return callback() which is required in every Twilio Function. We add a catch statement so we can know what’s wrong if SendGrid fails our request.

Forward Voicemail via SMS

1. At the top left of the screen, click the blue “Add” + button and select “Add Function”. You can leave the Function at the default, Protected.
2. Add a name and path for your Function, I used /forwardVMViaSMS.
   

1. Edit the `to` and` twilioFrom` (the Twilio phone number the SMS will come from) to meet your unique configuration, then "Save". Click the blue "Deploy All" button. If you'd like to understand what's happening, read on.
   
   The Function is included below. Feel free and copy, paste.

// Description // Send a single SMS  exports.handler = function (context, event, callback) {  // Make sure under Functions Settings tab:  // "Add my Twilio Credentials (ACCOUNT_SID) and (AUTH_TOKEN) to ENV" is CHECKED  const twilioClient = context.getTwilioClient();  // Begin Necessary Configuration  let to = '+14075550100';  let twilioFrom = '+15095550100'  // End Necessary Configuration   let body = `New Voicemail from: ${event.From}\n\nTranscription is:\n${event.TranscriptionText}\n\nListen to the recording\n${event.RecordingUrl}`;  twilioClient.messages  .create({  body: body,  to: to,  from: twilioFrom,  })  .then((message) => {  console.log('SMS successfully sent');  console.log(message.sid);  return callback(null, 'success');  })  .catch((error) => {  console.log(error);  return callback(error);  });  }; 

How your Function works

1. This Function initializes the Twilio Node helper library so we can call the /Messages resource to send an outbound SMS.
2. We pass in the from, which is a Twilio number in our account, to send the SMS from.
3. We pass in the to, which is the mobile number we will send the SMS to.
4. We pass in the body, which will contain our transcription and a link to listen to the recording. Note, email is optimal for long voicemail transcriptions as a single SMS can have a maximum size on most carriers of 1,600 bytes (usually 10 segments). An SMS is charged per segment, you can get more details on what a segment is here, Programmable SMS - API Basics and Best Practices.
5. The .then and .catch are called based on the resulting success or failure.

1. To get started, go to the Manage Flows Studio page, then click either the red “Create new Flow” button (if this is your first Flow) or the red plus (‘+’) sign (if it’s not your first Flow).

1. Next, give your first Flow a name.
   
   I called mine `studioLeaveVoicemailBlog` – either way, click “Next”. Scroll down and select “Import from JSON” from the menu, and click “Next” again.
2. Remove the initial `{}` and replace the content of the edit box with the JSON that can be downloaded here, and click Next.
   
   You should see the Studio canvas rendered out for you, as below.

1. Customize the widgets in the imported flow for your unique environment.
   • Edit the “initialGreeting” widget with your custom message, and click ‘Save’.
   • Edit the “attemptToReachContact” widget with the phone number you would like the incoming calls directed to and click ‘Save’. Note that the timeout for this widget is how long Twilio should attempt to ring this number (+ or - 5 seconds) before returning a DialCallStatus of no-answer.
   • Edit the “pleaseLeaveAVoicemail” widget with your custom message, click save.
   • Edit the “recordVoicemail” widget so the “Transcription Callback URL” points to either the Voicemail or SMS Function URL, based on how you want to be notified about the voicemail.
     You can find the URL by visiting the Functions we created above, selecting the correct service and Function and clicking the three vertical dots and choosing Copy URL. Click Save.
   • Edit the “thankYouConfirmation” widget with your custom message, click save.
2. Click the red “Publish” button to publish the changes to your flow.