Twilio API for making outbound calls with a speech stream - twilio

Question

I have a scenario where say at 5.00 AM every morning, I have a server side script / batch job that wakes up, selects a phone number from a list based on an algorithm, places a call to that phone number and uses text-to-speech to deliver a customized message. I have 2 questions,
Which Twilio API can I use to achieve this? Bear in mind there is no app UI and all the code would be on the back end. Think NodeRED flow or a Python script that is made to run at a given time.
Instead of specifying the text in the TwiML, can I pass say an audio stream from Watson's Text to Speech to the appropriate Twilio API?

Answer 1

To do this, you would need to use the programmable voice API from Twilio. This lets you play audio files, text to speech, make and manipulate phone calls, etc. I have never used Watson Text-to-Speech, but, if it can output an audio file you can play that with Twilio TwiML.
Here's an example in Node.
npm install twilio
//require the Twilio module and create a REST client
var client = require('twilio')('ACCOUNT_SID', 'AUTH_TOKEN');
client.makeCall({
to:'[phone]', // Any number Twilio can call
from: '[phone]', // A number you bought from Twilio
url: 'url/to/twiml/which/may/have/WatsonURL' // A URL that produces TwiML
}, function(err, responseData) {
//executed when the call has been initiated.
console.log(responseData.from); // outputs "[phone]"
});
The TwiML could look like this:
<Response>
<Play loop="1">https://api.twilio.com/cowbell.mp3</Play>
</Response>
This would play the cowbell sound from the Twilio API. Just a default sound. This could be easily generated to play a Watson sound file if you can get a URL for that.
You could do the same thing in Node, if you'd rather not build the XML manually.
var resp = new twilio.TwimlResponse();
resp.say('Welcome to Twilio!')
.pause({ length:3 })
.say('Please let us know if we can help during your development.', {
voice:'woman',
language:'en-us'
})
.play('http://www.example.com/some_sound.mp3');
If you were to take this toString() it would output formatted XML (TwiML):
console.log(resp.toString());
This outputs:
<Response>
<Say>Welcome to Twilio!</Say>
<Pause length="3"></Pause>
<Say voice="woman" language="en-us">Please let us know if we can help during your development.</Say>
<Play>http://www.example.com/some_sound.mp3</Play>
</Response>
Hopefully this clears it up for you.
Scott