Phreaking.

The classic art of manipulating telephone systems — originally analog PSTN, now VoIP and SS7 — to make free or unauthorized calls. It belongs to the Attacks & Threats category of cybersecurity.

The classic art of manipulating telephone systems — originally analog PSTN, now VoIP and SS7 — to make free or unauthorized calls.

Phreaking is the original telecom hacking subculture, born in the 1960s when enthusiasts noticed that the Bell System used in-band 2 600 Hz signalling on long-distance trunks. John Draper, known as Captain Crunch, found that a toy whistle from a cereal box produced the exact tone and seized trunks with it; blue boxes built by Steve Wozniak and Steve Jobs automated the trick. The magazine 2600 popularized the scene from 1984 onward. As Bell migrated to SS7, phreaking evolved into PBX hacking, calling-card fraud, IVR enumeration and modern SIP/VoIP attacks. Although out-of-band signalling killed the original whistle trick, the lineage is direct: today's SS7, SIP, IMSI-catcher and toll-fraud attacks all share its mindset of treating the telephone network as a hackable signalling system.

Defences for Phreaking typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: Phone phreaking, Blue boxing, Captain Crunch.