Blue box

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Blue Box at the Powerhouse Museum

Blue box

A blue box is an electronic device that was used to manipulate the telephone network to make free long-distance phone calls. The device simulates the tones used by the telephone system to route calls, allowing the user to bypass the normal toll system. Blue boxes were popular in the 1960s and 1970s among phone phreaks, who were hobbyists and hackers interested in exploring and exploiting the telephone network.

History[edit | edit source]

The concept of the blue box was first discovered by Joe Engressia, also known as "Joybubbles," who was a blind phone phreak with perfect pitch. He discovered that whistling at a certain frequency could control the telephone system. This discovery led to the development of the blue box, which could generate the necessary tones electronically.

The blue box gained widespread attention when Steve Wozniak and Steve Jobs, the co-founders of Apple Inc., built and sold blue boxes to finance their early ventures. Their involvement in phone phreaking is often cited as a significant influence on their later work in personal computing.

Technical Details[edit | edit source]

The blue box works by generating a series of multi-frequency (MF) tones that mimic the control signals used by the telephone network. These tones are used to seize a trunk line and then dial the desired number, bypassing the billing system. The most critical tone is the 2600 Hz tone, which is used to indicate that a trunk line is idle and ready for use.

Legal and Ethical Issues[edit | edit source]

The use of blue boxes is illegal, as it constitutes telephone fraud. The Federal Communications Commission (FCC) and telephone companies have taken measures to prevent and detect the use of blue boxes. Advances in digital switching technology and the transition to Signaling System No. 7 (SS7) have made blue boxes obsolete, as modern telephone networks no longer use the in-band signaling methods that blue boxes exploit.

Legacy[edit | edit source]

Despite their illegal nature, blue boxes played a significant role in the history of hacking and the development of the personal computer industry. They are often cited as an early example of hacker culture and the DIY ethic that would later become central to the computer revolution.

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Contributors: Prab R. Tumpati, MD