The [in]famous Cap'n Crunch Whistle

In 1971 Cap'n Crunch cereal gave away a plastic whistle known as the Captain Crunch whistle. When blown it makes a 2600 Hz sound.

People quickly learned that they could use a Captain Crunch whistle to make free long distance phone calls. As it turns out the Cap'n Crunch whistle's sound mimics one used by the phone system back then. 2600Hz signalled the AT&T long lines that a trunk line was ready and available to route a new call. In other words, the Cap'n Crunch whistle sidestepped the phone system's billing system back before digital phone switching (ESS) was implemented.

John Draper, Joe Engressia, and Bill from New York were pioneering phone phreakers who used the Cap'n Crunch whistle. Mr. Draper later went on to construct blue boxes.

My introduction to such matters took a quantum leap forward when as a young, impressionable high schooler I read Secrets of the Little Blue Box by Ron Rosenbaum, Esquire Magazine (October 1971 and the infamous June 1972 Ramparts magazine article (PDF) on how to make a black box. (Can you say 'Radio Shack project'?)

I have a Cap'n Crunch whistle. Or as the whistle itself says, a "Cap'n Crunch bo'sun whistle". Wanna hear how it sounds? No compare that to a pure 2600 Hz tone.

Wanna play with MF tones and more? Try Project MF. Be sure to watch the videos as well.

A big shoutout to Michael at Wall of Sound for jogging my memory, which inspired me to put this page together. Hats off to the producers of a show on phone freaking that stumbled across this page and borrowed by Cap'n Crunch whistle so Woz could blow it at the Tech Museum of Innovation in San Jose. The show has yet to air but I'm promised a credit.

Speaking of phones, try this page about the DTMF tones themselves. It includes sample sound files.

Matt Blaze described using a C tone to break wiretaps. Not that we're recommending you do any such thing.