This paragraph provides a summary of the Return2Me app, which is a customer support follow-up system that uses dynamic extensions to connect customers with their representatives. The app allows customers to dial a unique extension number to be connected directly with their representative, without exposing the actual direct line for the rep. The system uses Twilio's SMS API and IVR capabilities to send text messages and prompts users to enter an extension number. Once a valid extension is entered, the customer is connected with their representative. The app also stores extensions in a servlet context to keep the hack simple. Chris Foster, the developer behind Return2Me, shares his experience and knowledge on building dynamic extensions for customer support using Twilio's API.