This article guides readers through the process of integrating Twilio with a Rails 4 application. The author, Carter Rabasa, shares his personal experience of using Ruby on Rails to rapidly build software for his recreational sports league and how it influenced him to become a developer evangelist at Twilio. To integrate Twilio with a Rails app, one needs to sign up for a free account, obtain a phone number, and configure the webhook settings in the dashboard. The author then creates a new file `twilio_controller.rb` that defines an action called `voice`, which handles incoming phone calls by playing a message using TwiML. To make this work, the author uses the `Webhookable` Concern to set the HTTP response content type and render the TwiML object as raw XML. Finally, the app is deployed on a development server, and the author tests it using cURL and Ngrok to expose the server to the public internet.