phreaker
/ˈfrikər/
noun
- A person who explores or exploits telephone systems, especially to make free calls or to learn how the systems work.
- My uncle was a phreaker in his youth and could whistle the exact frequency to open a phone line.
- The documentary interviewed a former phreaker who now works as a cybersecurity expert.
- In the 1980s, a phreaker could make long-distance calls for free by mimicking the tones used by phone companies.