Twilio: Getting Started with Programmatic SMS

This is a Python Flask server that sends and receives SMS text messages. It is based on Twilio's own example for getting started with Python, but provides a little more configurability.

Setup

I suggest you use a Python virtualenv to keep things clean, and run pip install -r requirements.txt

You'll also need to set up configuration. You can export environment variables:

export TWILIO_ACCOUNT_SID=<your account SID>
export TWILIO_AUTH_TOKEN=<your auth token>
export TWILIO_SENDER=<your Twilio number that will send SMS>

or you can create a twilio.json file in the same directory as the app:

{
    "account_sid": "<your account SID>",
    "auth_token": "<your auth token>",
    "sender": "<your Twilio number that will send SMS>"
}

A sample twilio.json has been provided for your convenience.

Running

$ export FLASK_APP=sms.py
$ flask run

or

$ python sms.py

Using

There are two endpoints: one for sending messages, and one for responding to received messages.

Sending

The endpoint is /send, and it takes a path parameter that indicates the recipient number, like /send/2025550143. (That's a fake number, if you were wondering).

The request body contains a JSON document with an object with a message property, which will be the message that is sent to the recipient. Don't forget to send a Content-Type: application/json header.

Curl example

curl -d'{"message": "This is the message that will be sent."}' -H'Content-Type: application/json' localhost:5000/send/2025550143

Receiving

The receiving endpoint is the root of the webapp, /.

The receiving endpoint isn't hit directly by a user, but rather called by Twilio to respond to incoming messages.

Setup

You'll have to expose the app to the internet so Twilio can reach it. This is really easy with ngrok, or you can deploy to Heroku if you want something more long-lived than ngrok can offer. For experimentation, though, ngrok works nicely.

You'll also need to configure the number you're using to send messages to use the URL corresponding to where your app is running, which can be done from the Twilio Console, by clicking on the number you wish to configure and setting its Messaging Webhook.

Notes

This was developed with Python 3.5.2, and has not been tested with any other versions.