Send OTP codes with text to speech calls using Sinch and Node.js


In this tutorial I will show you how to use node.js to build a text to speech call that reads out pin-codes. To read more about the Sinch callout API please see the documentation.

Other use cases

Common use cases for this type of call are weather- and fraud alerts, when you suspect that an SMS is not delivered.

What you need to get started

  • Node development environment
  • Application - key and secret. Get one here if you don’t have one already - Sign up .
  • Some credits on your account. Set up your phone on the dashboard and my boss will give you $2 to get you started !


For this code snippet I will use the sinch-request npm package to sign the requests. This package is not required but it makes life a lot easier. Below code makes a call to +15551234567 and play “Your pin code is 1234” in US English when user is answering the call.

var sinchRequest = require("sinch-request");
var https = require("https");

var creds = { key: "your key", secret: "your secret" };

var bodyData = JSON.stringify({
  method: "ttsCallout",
  ttsCallout: {
    destination: { type: "number", endpoint: "+15551234567" },
    domain: "pstn",
    custom: "customData",
    locale: "en-US",
    prompts: "#tts[Your pin code is 1234]",

var options = {
  method: "POST",
  host: "",
  port: 443,
  path: "/v1/callouts",
  data: bodyData,

sinchRequest.applicationSigned(options, creds);
var req = https.request(options, function (response) {
  var data = "";
  response.on("data", function (chunk) {
    data += chunk;
  response.on("end", function () {
    console.log("Response body: " + data);
    //here you can i.e save your callid,

Next steps

In the next tutorial I will show you how to make IVR menus that enable you to collect input from the user.

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