Receiving SMS and MMS

Inbound texts are delivered via a webhook to your server. The webhook will be an HTTP POST request that includes a payload with information about the inbound SMS or MMS. To receive the message, you’ll need to create a minimal web application that will accept the webhook request.

Prerequisites

Check out the [API prerequisites] to setup your Python development environment for this guide.

Receive an SMS or MMS

1. First, you’ll need to install Flask , a minimal web framework written in Python.

pip install flask

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2. Create a Flask application to accept webhooks. Create a new file called receive.py and copy the code below into the file:

import os
from flask import Flask, request

app = Flask(__name__)

@app.route('/webhooks', methods=['POST'])
def webhooks():
    body = request.json

    print(body)

    return '', 200


if __name__ == "__main__":
    app.run(port=5000)

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This file does a few things, so we'll step through each line one by one.

import os
from flask import Flask, request

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Make the code from the Flask library available in the receive.py file.

app = Flask(__name__)

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Create a new instance of the Flask class, passing in the module attribute __name__ as the name of the Flask application.

@app.route('/webhooks', methods=['POST'])

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Next, you’ll define a route using a decorator function. We define the path as /webhooks and specify that the path will respond to the HTTP POST method. This route will accept webhooks from Telnyx when your Telnyx number receives an SMS or MMS.

def webhooks():

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Finally, the print function will print the body of the request so you can see it in your terminal. For the purposes of this demo, you'll print the body of the message to the terminal to see the contents of the message. But in a real application, you'd most likely take some action based on the type of event that was received.

print(body)

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The last lines in the file check to see if the name of the module is __main__, and if it is, starts the application on the port 5000.

if __name__ == "__main__":
    app.run(port=5000)

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3. Now that you’ve set up your application, make sure it's ready to receive requests. From your terminal, run the below:

python receive.py

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You should see something like the following:

* Serving Flask app "receive" (lazy loading)
* Environment: production
  WARNING: Do not use the development server in a production environment.
  Use a production WSGI server instead.
* Debug mode: off
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

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This means our server is listening on port 5000. You're almost ready to receive an SMS or MMS.

4. The final step involves making your application accessible from the internet. So far, we've set up a local web server. This is typically not accessible from the public internet, making testing inbound requests to web applications difficult.

   The best workaround is a tunneling service. They come with client software that runs on your computer and opens an outgoing permanent connection to a publicly available server in a data center. Then, they assign a public URL (typically on a random or custom subdomain) on that server to your account. The public server acts as a proxy that accepts incoming connections to your URL, forwards (tunnels) them through the already established connection and sends them to the local web server as if they originated from the same machine. The most popular tunneling tool is ngrok. Check out the [ngrok setup] walkthrough to set it up on your computer and start receiving webhooks from inbound messages to your newly created application.

5. Once you've set up ngrok or another tunneling service you can add the public proxy URL to your Messaging Profile. To do this, click the edit symbol [✎] next to your Messaging Profile. Under “Inbound”, paste the forwarding address from ngrok into the Webhook URL field. Add /webhooks to the end of the URL to direct the request to the webhook endpoint in your Flask app.

   For now you'll leave “Failover URL” blank, but if you'd like to have Telnyx resend the webhook in the case where sending to the Webhook URL fails, you can specify an alternate address in this field.

6. Now that your Messaging Profile is configured, you're ready to receive an SMS or MMS.

   Send a message from your phone to your Telnyx number. Soon after you’ll see an event printed in your terminal when the inbound SMS or MMS request is received by your Flask application.

Congrats, you’ve learned how to recieve messages with Telnyx.