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Kelly Andrews for Vonage

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Translating SMS Messages With Azure Translator Text

In my previous posts, I showed how you can translate text messages with the Google Translation API, AWS Translate. and IBM Watson Language Translator.


In this post, I show you how to create an inbound Nexmo SMS webhook and translate the message into English using the Azure Translator Text.

In order to get started, you will need the following items set up:

Create Your Project

You will only need a couple of packages to get things going.

Initialize the project and then install the above requirements using npm or yarn.

npm init && npm install @azure/ms-rest-js @azure/cognitiveservices-translatortext express dotenv body-parser
# or
yarn init && yarn add @azure/ms-rest-js @azure/cognitiveservices-translatortext express dotenv body-parser

Once installed, create an index.js and .env file.

touch index.js .env

Next, open the index.js file and put the following code inside:

'use strict';

const express = require('express');
const bodyParser = require('body-parser');
const CognitiveServicesCredentials = require("@azure/ms-rest-js");
const { TranslatorTextClient } = require("@azure/cognitiveservices-translatortext");

const app = express();

app.use(bodyParser.urlencoded({ extended: true }));

const server = app.listen(3000, () => {
  console.log(`Express server listening on port ${server.address().port} in ${app.settings.env} mode`);

This will set up the server to run the example.

Installing ngrok

Publicly available webhooks are required so that Nexmo can communicate with the application to receive incoming SMS messages. You could push your code up to a publicly available server, or you can use ngrok to allow for public traffic to reach your local application.

You can learn more about installing ngrok with this post. After you have everything ready to go you can start ngrok using the following command to create your tunnel.

ngrok http 3000

Make a note of the ngrok address, as you will need that in a later step.

Setting Up Azure Translator Text

Next you can set up the Azure Translator Text service in the Azure portal. Start by opening the portal and clicking Create New Resource.

Azure Portal Home Page

On the next screen do a search for Translator Text and click on the result to be taken to the Translator Text info page. Click Create to start the process.

Translator Text Create Resource Screen

Fill out the name, select Pay As You Go and the resource group, and then click Create at the bottom of the page.

Translator Text Create Resource Details

The creation process take a few moments, so relax for a bit until that completes.

Open up the .env file first, and copy and paste the following:


Grab the key and endpoint from the quick start page and update the .env file with that information.

During my trials, I attempted to use the services endpoint presented in the dashboard, but didn’t have any luck getting it to work correctly. The URL above is the global endpoint that will work if you run into the same troubles.

Translator Text Resource Quickstart

Setting Up Nexmo Inbound SMS Messages

This example requires a phone number from Nexmo to receive inbound messages. We can do this by using the Nexmo CLI right from a terminal.

Purchase a Virtual Phone Number

First, purchase a number directly from Nexmo (feel free to use a different ISO 3166 alpha-2 country code as needed).

nexmo number:buy --country\_code US

You haven’t created the route as of yet, however you will name it /message. The phone number needs to be linked to this route so inbound messages know where to go. Get the ngrok host name from the previous setup and use it here:

nexmo link:sms phone\_number https://my-ngrok-hostname/message

Now the Nexmo webhook is set up to route inbound SMS messages.

Finish the Application

The only step now is to create the Express route and functions to handle the incoming SMS message and the translations.

Build the Webhook

We can set up the route handler first. Nexmo allows the setting of a default SMS webhook behavior. In the settings panel you can change the default HTTP method used. Mine is set to POST-JSON, and I recommend using this setting. If you are unable to modify your setting, the code used here will handle all three options.

Default Nexmo SMS HTTP Method

Open up the index.js file, and at the bottom, paste the following code:

// Reading the inbound SMS messages
const handleRoute = (req, res) => {

  let params = req.body;

  if (req.method === "GET") {
    params = req.query

  if (! || !params.msisdn) {
    res.status(400).send({'error': 'This is not a valid inbound SMS message!'});
  } else {


This handler will be passed directly to the /message route. If the incoming message HTTP method is POST, the handler uses req.body, and uses req.query for the GET option. It then checks the inbound payload ensuring it has the correct info, then sends the object to the translateText method to display the translation.

Now you can add the route and proper HTTP methods to the application.

  .all((req, res) => res.status(405).send());

The above code will create the GET and POST methods to handle either from the inbound SMS webhook message. If any other method is used, a 405 - Method Not Allowed response will be returned.

The webhook is ready to go and the final piece is the actual translations.

Translation Method

In the previous step we call translateText. This step will create that method.

You will initially get your credentials by using CognitiveServicesCredentials.ApiKeyCredentials. This will need to be passed as the first parameter to the TranslatorTextClient constructor.

After create the client, use the translate method to translate the text. The first argument is an array of languages you wish to translate the text into—allowing you to translate into multiple languages. The service will automatically detect the incoming language if it can. The second argument is an array of objects for the text you want to translate.

function translateText(params) {
  const creds = new CognitiveServicesCredentials.ApiKeyCredentials({ inHeader: { 'Ocp-Apim-Subscription-Key': process.env.TEXT_TRANSLATION_SUBSCRIPTION_KEY } });
  const client = new TranslatorTextClient(creds, process.env.TEXT_TRANSLATION_ENDPOINT);

    .translate(["en"], [{text:params.text}])
    .then(result => {
      console.log(`Original Text: ${params.text}`);
      console.log(`Translation: ${result[0].translations[0].text}`)
    .catch(err => {
      console.error("error:", err);

Now you can test out the functionality by starting the server and sending a text message to the number you purchased earlier.

node index.js
# Text "Hola" to your phone number

# expected response
Original Text: Hola
Translation: Hello

The Azure Translator Text full response object has a lot of details as well, so you can change the response to include console.dir(translationResult, {depth: null}) to see the full payload.


Azure Translator Text is a great tool to translate your inbound messages from Nexmo. This example only scratches the surface, but should be a good start. You can venture off in several directions from here using this as a jumping point. Let me know what ideas you have for using these two services together.

You can find a completed version of this tutorial at

If you want to learn more about the Extend projects we have, you can visit to learn more.

The post Translating SMS Messages With Azure Translator Text appeared first on Nexmo Developer Blog.

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