The Hertzian Collective is an interactive art installation that uses a toll-free phone number and keypad controls to allow visitors with mobile phones to control a video-projected rhythm sequence, creating a collaborative sound/text mash-up experience. The project was built using Twilio's API and programming languages such as Python, and took approximately six months to complete. The installation is part of the Mobile Experience Lab at the Ontario College of Art & Design and showcases the potential for mobile phones to be used as interactive tools in art installations. The project's creator, Geoffrey Shea, has been working with software artist Rob King on various playful projects, including a musical instrument and a game that utilized convoluted phone network patches.