Someone who likes to explore the workings of the telephone system, such as switching, call routing, etc. Phreaks are always trying to keep up with the latest telecom innovations.
Phreak (or phreaking/phreaker) is a term used to describe the early hackers in the late 70's-early 90's who manipulated the tone-based telephone switching systems to conduct unauthorized activity within that system. Although these "phreakers" rarely had malicious intent, their curiosity often got them arrested and heavily punished.
A phreaker is someone who is driven to explore the phone system through legal means or otherwise to understand how it operates, and marvel at it's greatness.
"Being able to beige box doesn't make you a phreaker anymore than being able to write makes you a poet."