The article explains how to build a one-time passcode protected conference line with Twilio Verify and Ruby. It starts by adding a list of permitted callers to protect the conference line, then adds OTP verification using Twilio Verify. The application uses Rails and Twilio's REST API to authenticate users and verify their phone numbers. The code is tested using ngrok and Twilio's webhooks, and the article concludes with suggestions for further development, including expanding the database and exploring other OTP channels such as email.