What Does Phreaking Mean?

Phreaking is a slang term for hacking into secure telecommunication networks. The term phreaking originally referred to exploring and exploiting the phone networks by mimicking dialing tones to trigger the automatic switches using whistles or custom blue boxes designed for that purpose. Generally speaking, it was curiosity about how phone networks operated that motivated phreaks, rather than a desire to defraud telecommunications companies.

Techopedia Explains Phreaking

Phreaks - a combination of phone and freaks - were a defined subculture in the 1970s. Using relatively low-tech hacks like the plastic whistle from Captain Crunch boxes to the do-it-yourself blue boxes, phreaks maintained a social network similar to that of ham radio enthusiasts. The rising complexity of network security meant that more explicit lines needed to be crossed in order to continue phreaking.