The application allows users to purchase phone numbers from Twilio for use in marketing campaigns, forward incoming calls to a salesperson, and display charts showing data about the phone numbers and calls they receive. The backend code is written in Python and Django, with a custom utility module used to search for available phone numbers, purchase new numbers, and associate them with lead sources. The frontend code is a simple JavaScript application that fetches call tracking statistics in JSON from the server and displays them in colorful pie charts using Chart.js.