Early Hackers Used Whistles from Cap’n Crunch Cereal Boxes

After a story about blue boxes was published in Esquire in 1971, the then-college student Wozniak and his friend Steve Jobs tracked Draper down to learn all they could. Jobs and Wozniak’s first joint-business venture was selling blue boxes to aspiring phreakers. A collection of the whistles are displayed at the Telephone Museum in Waltham, Massachusetts, while the Computer History Museum in Mountain View, California, has one of Wozniak’s handmade blue boxes.

Source: www.atlasobscura.com