A cereal-box whistle that could trick the phone system into free calls

In today's edition of Dan Lewis's excellent Now I Know newsletter, there's a photo of a red plastic whistle that used to come in boxes of Cap'n Crunch cereal in the 1960s. Besides being a cool-looking whistle, it had a unique property that made it popular among phone hackers. — Read the rest The post A cereal-box whistle that could trick the phone system into free calls appeared first on Boing Boing.