A developer has built an Interactive Voice Response (IVR) system using Ruby, Sinatra, and Twilio to create a simple IVR system that can guide callers through different options. The system uses a database-backed approach with data mapping and analytics to track caller behavior. The code includes models for Steps, Metrics, and Call Handlers, as well as templates for displaying the steps and metrics in an HTML interface. The system also includes utility routes for deleting all data or rebuilding the step tree on demand. The developer has created a GitHub repository with the code and invites users to try out the IVR system by dialing one of the provided numbers or downloading the code to configure their own version.