Callin' Oates is an example of how Twilio's API can be used to create a successful app that reached hundreds of thousands of users, built from someone's first experience with the platform. The app was created by Michael Selvidge, a corporate communications manager at Twilio, who developed a basic phone menu allowing callers to choose their favorite Hall and Oates song. After sharing it with private eyes, the app snowballed into a viral sensation, reaching mainstream media popularity and attracting over 300,000 calls. The Twilio team was caught off guard by its success, but took advantage of the instant scaling capabilities of the platform to support the surge in traffic. The app's popularity led to numerous news hits, social media conversations, and even appearances on TV shows, making it a brilliant example of how Twilio can be used for innovative marketing and public service initiatives.