This tutorial provides a simple way to receive an SMS message using Ruby, Sinatra, and Twilio. To start, install Sinatra and create a file called `app.rb`, which requires Sinatra and defines a route `/message` that accepts a POST request with details about the inbound SMS. The code then parses the parameters, extracts the sender's number and the message body, and sends a response using TwiML XML tags. The app needs to be deployed to a publicly accessible URL or accessed via ngrok to receive incoming SMS requests from Twilio. Once set up, users can send an SMS to their new phone number and see a customized response with the sender's number and message body.