phreaker

Phreakers are people who specialize in attacks on the telephone system. The word, which became popular in the mid-1980s, is probably a combination of the words phone and freak. (Phreakers are also known as "phreaks" or "phone phreaks.") In the early days, phreakers whistled or used an instrument to mimic the tones the phone system then used to route calls and identify payment, especially as a way to avoid paying for an expensive call. Modern phreaking involves breaking into and manipulating the phone company's computer system, making it a specialized kind of hacking.