This is a tutorial on building a simple application using Node.js and Twilio's Voice API that handles over 10,000 calls to senators and representatives in Congress. The application uses the Sunlight Foundation API to look up representatives for a given zip code and dials them in sequence. The app starts by setting up an Express route to handle new inbound communications from Twilio, asking the user for their zip code, receiving the input, looking up representatives, and dialing them. The server is then hosted on port 3000 using LocalTunnel, and a Twilio phone number is configured to forward HTTP requests to the application. Once set up, users can dial the phone number, enter their zip code, and be connected with their representatives in Congress. The project showcases how engineers can apply their skills to important causes and highlights the potential of simple tools for mobilizing large numbers of people.