Build a “Serverless” Twilio SMS + Call Forwarding Bot in 7 Minutes using Node.js + StdLib

Keith Horwood
Jun 14, 2017 · 9 min read

Since 2009, Twilio has enabled developers to seamlessly build SMS and Voice technology into their apps, handling everything from basic user notifications, connecting drivers and passengers in apps like Uber and Lyft, to conference calling and more. If you haven’t had a chance to incorporate Twilio’s services into your product yet, here’s your chance to start! We’re happy to team up with Twilio’s functionality to show you how to bring Voice + SMS into your product or company in only a couple of minutes with StdLib!

Maybe you’ve used Twilio before, or maybe you haven’t but you’re extremely interested in playing with programmable telephony and bringing it to your team or company. With the past success of our “Build” articles (like Build a Slack Bot in 9 Minutes), we’re excited to share StdLib’s quickest article yet — we’re happy to introduce how you can build a Twilio Messaging Hub in only 7 Minutes with StdLib!

If you haven’t used StdLib before you’re in for a treat — StdLib is the fastest way to ship business value via code. It’s effectively a package manager for APIs that’s built upon new “serverless” architecture, meaning you never have to worry about managing servers or allocating resources for scale. Write a function, deploy, and you’re ready to go! We also have a growing ecosystem of integrations contributed by other developers that are extremely easy to plug in to.

Once you’ve created your StdLib service in Minute 4, you’ll get a README.mdfile that shows you how to hack your Twilio + StdLib Messaging Hub to your own needs.

What You’ll Need Beforehand


Minute 1: Create Your Twilio Phone Number

The first thing you’ll want to do to get your Stdlib + Twilio messaging hub operational is grab a new phone number for your Twilio Account. First, make sure you’re logged in to your Twilio Account at https://www.twilio.com/login.

Log In to Twilio

From here, you’ll be at your Twilio Console. If this is your first time with Twilio, you’ll see a screen that looks like this (below). On the left menu, hit the button with the circle and ellipsis “(…)” inside:

You want to select “All Products and Services” on the grey bar on the left

From here, a slider menu will pop out. You want to select Phone Numbers under the Super Network heading:

Click “# Phone Numbers”

To add your first phone number, hit “Get Started”:

And then “Get Your First Twilio Phone Number”:

You’ll see a popup suggesting a random number for your geolocation, in this case, 415 is San Francisco. Click “Choose this Number” to continue quickly. (You can buy other numbers later.)

You’ll be greeted with a success message. Awesome!


Minute 2: StdLib Account Setup

In order to create a robust messaging hub, you’ll next need to set up your StdLib Account. You’ll use StdLib to host your Twilio Hub using infinitely scalable “serverless” architecture from a single, maintainable codebase, and to hook into other integrations on StdLib (for example, using utils.image to format images you receive via MMS or using devin.income-predictor to see income ranges for the zip code associated with an incoming phone number). Simply visit https://stdlib.com and click “Sign Up Free” to create your account.

Click “Sign Up” to Create an Account

Minute 3: Create a StdLib Workspace

StdLib natively runs Node.js 8.0.0 (yes, the newest version) so to ensure there are no compatibility issues you’ll likely want to run it (though Node 6 and 7 will work for this example). You can install the latest version of Node from the Official Node.js Website. Once complete, open up your Terminal or Command Line and install the StdLib Command Line Tools with the following:

$ npm install lib.cli -g

This gives you access to the lib command for service management and execution. Next, create a stdlib directory for your StdLib services.

$ mkdir stdlib
$ cd stdlib
$ lib init

Log in using the credentials you created in the previous step. That’s it!


Minute 4: StdLib Service Creation

Next you’ll create your StdLib service from the command line. We’ve created a special twilio template to allow you to ship a prototype of your own Twilio Hub in only a few seconds.

$ lib create -t twilio

You’ll be asked to enter a Service Name, we recommend twilio-hub for the purposes of this tutorial. You’ll see some NPM packages being installed locally and your service directory being created:

Once complete, you’ll be told to enter your service directory. Do so with the command:

$ cd user/twilio-hub

Where user is, of course, your StdLib username. (In my case, it’s keith.)

From here, you can try running some SMS commands (these will be the responses for “more” or “whoami” sent to your Twilio number) with:

$ lib .messaging.more

And see the result:

The SMS response to people who message your number with the text “more.”

Or, alternatively, turn on debug mode with -d to see what’s going on behind the scenes:

$ lib .messaging.whoami -d

Since this isn’t actually being triggered by Twilio’s webhook, execution information (zipcode, city) reads as undefined, so this is expected.


Minute 5: Configure Your StdLib Environment

As a next step, we’ll want to make sure StdLib knows all of our Twilio Account details. To set this up properly, first open up env.json in the StdLib service directory you just created, user/twilio-hub/env.json where, again, user is your username.

You can see three different environments: local, dev and release. These are intended for different execution contexts — when running locally, the environment variables in local are used, you can deploy to a dev environment in the cloud, or a production release environment. We generally recommend at least using a different phone number.

Make sure, for the purposes of this tutorial, you fill in the dev and local variables with the same values.

To fill in "STDLIB_TOKEN" visit https://dashboard.stdlib.com/dashboard/, log in, click Library Tokens on the left, then Show Token to reveal your token. Copy and paste it into your environment variables.

Click “Show Token” to reveal your token, then copy it.

Next, "TWILIO_ACCOUNT_SID", "TWILIO_AUTH_TOKEN", and "TWILIO_NUMBER" — these are all available from your Twilio Console at https://www.twilio.com/console. Copy your ACCOUNT SID directly, and click the eyeball beside your AUTH TOKEN to reveal it and copy it as well.

Copy your Account SID and your Twilio Auth Token into your Environment Variables

To find your Twilio Phone Number you previously created, visit https://www.twilio.com/console/phone-numbers/incoming. Click on the red, highlighted number you created in Minute 1.

Click on the Red Text to Configure Your Number

From the next screen, copy and paste the PHONE NUMBER value in the format +1234567890 to your "TWILIO_NUMBER" value.

Copy the “PHONE NUMBER” value

Finally, the "CALL_FORWARD_NUMBER" value can be filled in with any phone number of your choosing, it is the number that your Twilio Hub will automatically redirect incoming calls to. Use the format +1234567890 again (make sure it’s in quotes). Best bet is to use a personal phone number for demonstration purposes.


Minute 6: Deploy and Configure Webhooks

You’re almost done! The very last step is to deploy your StdLib Twilio Hub (with the appropriate environment variables set above) and then configure Twilio Webhooks to point to StdLib.

To deploy your StdLib Twilio Hub in a dev environment, simply open up your command line in your service directory and type:

$ lib up dev

You’ll see the progress of your service deploying to a development environment, and be greeted with a list of available HTTP endpoints corresponding to everything in your functions/ directory.

Now that your service is live, go back to the Twilio Manage Numbers dashboard https://www.twilio.com/console/phone-numbers/incoming and select your phone number again. Scroll down to Voice & Fax first:

Enter in your “voice” endpoint to Voice & Fax

On this form, beside A CALL COMES IN, make sure Webhook is selected in the dropdown and use the value https://<user>.api.stdlib.com/twilio-hub@dev/voice/ (where <user> is of course, your username). Note that the hostname api.stdlib.com is our functions gateway, where all of your services and functions will be deployed to.

Next, scroll down to Messaging and enter in https://<user>.api.stdlib.com/twilio-hub@dev/messaging/ in the A MESSAGE COMES IN Webhook handler.

Enter in your Messaging Handler details, and hit Save

Finally, hit Save in the bottom left.


Minute 7: Add Verified Phone Numbers

If this is your first time signing up with Twilio, you’ll be using a trial account. Trial accounts have limitations on numbers they can send messages to or forward calls from. To make sure your Twilio Messaging Hub on StdLib works as you expect it, use the verified phone numbers list to add any phone numbers that you want to forward calls or send messages to.

https://twilio.com/user/account/phone-numbers/verified

By default, the phone number you registered your account with should already be listed here.


That’s It!

Your Twilio Messaging Hub on StdLib is live! You can now send SMS messages to your Twilio Number to receive an automated response and make calls to your number to have them forwarded. If you’re using a Twilio trial account, make sure you’ve added verified numbers in Minute 7. Otherwise, you’re good to go!

A Twilio Bot Interaction using StdLib

You can modify the behavior of your SMS Bot by visiting the /functions/messaging/ directory in your StdLib service. The default responses are are to “whoami” and “more.” This messaging hub also handles MMS (media, picture) uploads.

Gotchas and Production Releases

If at any point you lose track of your StdLib username or what your webhook callbacks should be, they’re listed when you deploy a service with $ lib up dev.

If you’re not getting the expected responses when you play, Twilio has an amazing debugger at https://www.twilio.com/console/dev-tools/debugger.

To ship a bot / messaging hub to production, we recommend using a different phone number. Configure your release environment variables in env.json to the appropriate settings, set your version in package.json to 1.0.0 (or whatever you’d like, really), ship a release with $ lib release and then you can use https://<user>.api.stdlib.com/twilio-hub@1.0.0/voice/ and https://<user>.api.stdlib.com/twilio-hub@1.0.0/messaging/ as your voice and messaging endpoints for your production phone number.


Thank You!

If you’d like to keep track of future StdLib updates and more Twilio fun, please follow us on Twitter at @StdLibHQ — or you can follow me, specifically at @keithwhor. Thanks for reading!


At StdLib we’re focused on making the lives of software developers easier by getting them back to doing what they love best — writing code and building awesome products. If you’d like to help us on our mission, please reach out to careers@stdlib.com with a little bit about yourself!

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Keith Horwood

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Solving problems since 1988.

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