Phreaking: /freek'ing/ [from `phone Phreak'] N. 1. The Art And Science Of Cracking The Phone Network (so As, For Example, To Make Free Long-distance Calls).

:phreaking: /freek'ing/ [from `phone phreak'] n. 1. The art and
science of cracking the phone network (so as, for example, to make
free long-distance calls). 2. By extension, security-cracking in
any other context (especially, but not exclusively, on
communications networks) (see {cracking}).

At one time phreaking was a semi-respectable activity among
hackers; there was a gentleman's agreement that phreaking as an
intellectual game and a form of exploration was OK, but serious
theft of services was taboo. There was significant crossover
between the hacker community and the hard-core phone phreaks who
ran semi-underground networks of their own through such media as
the legendary "TAP Newsletter". This ethos began to break
down in the mid-1980s as wider dissemination of the techniques put
them in the hands of less responsible phreaks. Around the same
time, changes in the phone network made old-style technical
ingenuity less effective as a way of hacking it, so phreaking came
to depend more on overtly criminal acts such as stealing phone-card
numbers. The crimes and punishments of gangs like the `414 group'
turned that game very ugly. A few old-time hackers still phreak
casually just to keep their hand in, but most these days have
hardly even heard of `blue boxes' or any of the other
paraphernalia of the great phreaks of yore.
-- The AI Hackers Dictionary