How to send SMS from IoT Devices using Twilio

How to send SMS from IoT Devices

SMS messages are the universal way to quickly send information to someone, with a high reach-ability, quick delivery, and high rate of opening. And today, we are going to have a look at how to receive SMS messages right from your IoT Hub.

For this tutorial, we will setup a standard scenario: Imagine that you have a house with intrusion sensors, and you want to be alerted by SMS when one of them is triggered. We can do this easily with IoT Hub.

First, the plan: a Device will send a message, which will be caught by an IoT Hub Route, which then triggers a Serverless Function which will finally call the SMS provider API.

For the SMS provider we chose Twilio, as they offer a small amount of credit when you register, which should be enough to play with this tutorial. If you prefer to use another SMS provder, you can use it as long as they provide API access.

We are going to do things in reverse order:

Get Twilio credentials
Create a Serverless Function
Set up an IoT Hub and configure a Route to the Function
Give it a try!

Requirements
You have an account and are logged into console.scaleway.com

Getting Twilio credentials

1 . Create a Twilio account on their website.

2 . Validate your email address and your phone number to finish to sign up process.

3 . If you want to add another verified phone number, go to Verified Caller IDs.

On your project’s dashboard, start by getting a phone number:

4 . Head to the Messaging / Setting Started page and click Show your Auth Token.

In the text area below you should see something like:

curl 'https://api.twilio.com/2010-04-01/Accounts/<your account ID>/Messages.json' -X POST \
--data-urlencode 'To=+01234567890' \
--data-urlencode 'From=+12345678901' \
-u <your Account ID>:<your Auth Token>

5 . Write down the From and To phone numbers, along with your Account ID and Auth Token, we will need these in the Serverless Function.

That’s it for Twilio, let’s proceed to the Serverless Function setup.

Create a Serverless Function

1 . Head to the Serverless section of your Scaleway console and create a new Namespace.

2 . Once done, create a new Function, set python3 as the runtime, paste the following code in the code editor, choose any name for your function, leave everything else with the default settings and click create.

#!/usr/bin/python3
import urllib
import urllib.request

twAccount = '<Account ID>'
twToken = '<Auth Token>'
smsFrom = '<"From" Phone Number>'
smsTo = '<"To" Phone Number>'

url = "https://api.twilio.com/2010-04-01/Accounts/{}/Messages.json".format(twAccount)

password_mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
password_mgr.add_password(None, url, twAccount, twToken)
handler = urllib.request.HTTPBasicAuthHandler(password_mgr)
opener = urllib.request.build_opener(handler)
urllib.request.install_opener(opener)

params = urllib.parse.urlencode({
    'From': smsFrom,
    'To': smsTo,
    'Body': 'This is an alert from Scaleway IoT Hub!'
    }).encode('ascii')

urllib.request.urlopen(url, data=params)

Don’t forget to replace empty variables (twAccount, twToken, smsFrom and smsTo) with the information you got in Twilio console.

That’s it for the function. While is it being deployed, write down the Function endpoint (under the Function settings tab) and let’s proceed to IoT Hub configuration.

Creating and setting-up an IoT Hub

Here we are going to set up an IoT Hub to trigger the Function when we receive the alert message from the sensor. Let’s say we want the Hub to trigger our function when a message is published on the my-home/alert topic.

1 . Create an IoT Hub in the IoT Hub section of Scaleway console.

2 . Give it a name, choose the Shared plan (this plan is free) and click the Create a Hub button.

3 . Click on your newly created Hub in the list, go to the Networks tab and write down the Hub endpoint.

4 . Now the Hub is created, click on it, go to the Routes tab, and click Create a Route.

5 . Choose any name, type in my-home/alert in the Topic field, select REST Query under Route type, paste the Function endpoint in the Endpoint field, and click the Add new Route button.

That’s it! Our IoT Hub is ready to send SMS messages!

Testing the configuration

1 . Head back to the Devices tab of your IoT Hub. Add a new Device, name it as you wish, choose Allow insecure connection and click the Add device button. On the Device overview page, click the MQTT Webclient button. The client will open and automatically connect.

Note: We chose to allow insecure connection to simplify this guide, in a production environment you will want to deny insecure connections and use mutual TLS authentication.

2 . To simulate your sensor device simply write my-home/alert in the Topic box and click Publish.

3 . Verify on your phone that the message was received.

For more information about Scaleway IoT Hub refer to our product documentation

How to send SMS from IoT Devices using Twilio