September 28, 2025, 7:02 am | Read time: 5 minutes
What do a blind student, breakfast cereal, and a plastic whistle have to do with the hacker scene? Quite a lot. The story begins in the early 1950s in the U.S., in Richmond. There, Josef Carl Engressia has been playing with his parents’ phone since he was four years old. Josef was born blind. As it later turns out, he has perfect pitch, meaning he can determine the pitch of a sound without any aids. How he became a kind of forefather of the hacker scene is what TECHBOOK tells in this article about phreaking.
When the blind Josef picked up the phone receiver, he entered a world full of sounds. For him, as a non-seeing person, it was a fascinating world. In the era of analog telephony, there were many sounds. Just dialing the numbers sounded like a melody to the child. The long tone for a free line or the busy signal’s hectic noise magically attracted Josef.
One day, he heard a tone with a frequency of 2600 hertz. He was driven by ambition. He whistled into the phone’s receiver, trying to match the exact pitch. After several attempts, the line went dead. What did that mean?
“Phone Phreaks” Fool Telephone Companies
Josef thought the dead line was a malfunction. So he called the phone company to report the error. But he was informed that it was not a malfunction. Commands could be sent into the phone network using the 2600 hertz tone frequency.
So Josef tried his whistle trick again. While the line seemed dead, he did the following: He dialed a phone number, and someone answered on the other end. However, this call didn’t cost a single cent. The child had accidentally discovered a loophole in the phone network.
Over time, more and more people in the U.S. learned about this loophole. A kind of secret society of so-called “Phone Phreaks” developed. They fooled the phone companies and made free local and long-distance calls. Later, the term “phreaking” was coined for this.
Read also: Over 30 Years of SMS – The Story Behind the Short Message
Where does the term phishing actually come from?
These Nude and Sex Scenes in Series and Films Are Real
A Plastic Whistle as a Business Model
Since the financial damage to the phone companies was initially limited, they did nothing. Until one day, John Draper heard about the ultimate whistle. The trained engineer was interested in radios in his spare time. He also loved the breakfast cereal called Cap’n Crunch. The packaging regularly included small gifts. In the late 1960s, for example, an inconspicuous plastic whistle.
But John Draper immediately recognized the potential of this toy. With a little trick, it could produce a tone. The frequency was exactly 2600 hertz. John Draper then went to his home workshop and tinkered with a device. He named it the Blue Box. The sole purpose of the Blue Box: to send a tone with a frequency of 2600 hertz into the phone network to make free calls around the world.
Over time, not only the “Phone Phreaks” but also law enforcement became interested in the Blue Box. The affected phone companies were no longer standing idly by. John Draper spent nearly half a year in prison in the mid-1970s. This did not harm his later career as a software developer, including for Apple.
“Phreaking” Remains a Problem Today
A friendship developed over the Blue Box between John Draper and Steve Wozniak, one of Apple’s founders. Together with his buddy Steve Jobs, Wozniak even made his own Blue Boxes before his time at Apple, although not on as large a scale as John Draper had.
The phone companies responded to “phreaking.” The reason was not only the financial damage, but the free calls were increasingly used for criminal activities. This illegal form of telephony made it difficult to trace calls, making “phreaking” attractive to criminals.
With the development of telephone technology from analog to digital, “phreaking” has not disappeared, but it is no longer as significant as it was in the 1960s and 1970s. In the hacker scene, there are still people trying to manipulate phone lines and misuse the digital network for their own purposes. However, the technical effort has become much more complex. A whistle is no longer enough.
Josef Carl Engressia, who accidentally discovered this loophole as a child, passed away in 2007. By that time, the public was well aware of the difficult circumstances under which young Josef grew up. His great interest in the phone with its fascinating sounds was not just childlike curiosity but also helped him escape, at least for a while, from the horrific adult world that surrounded him. In the hacker scene, the name Josef Carl Engressia still holds an honorable reputation today.