Playing an audio file in response to a call to a Twilio number from Azure

index.js

// Use Twilio in this app
const VoiceResponse = require('twilio').twiml.VoiceResponse;

// Export the function from Azure
module.exports = function (context) {
  // Log the response in Azure 
  context.log('JavaScript HTTP trigger function processed a request.');

  // Create a new TwiML response, this time using voice
  const twiml = new VoiceResponse();
  // Play the secret link that's disguised
  twiml.play('https://your-twilio-asset-link-here'); 

  // Let Twilio know what we're responding with 
  context.res = {
    status: 200,
    body: twiml.toString(),
    headers: {'Content-Type': 'application/xml' },
    isRaw: true
  };

  // We're done!
  context.done();
};