From The Free On-line Dictionary of Computing (8 July 2008) [foldoc]:
phreaking
<jargon> /freek'ing/ "phone phreak" 1. The art and science of
cracking the telephone 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).
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.
[Jargon File]
(1994-11-09)
From Jargon File (4.4.4, 14 Aug 2003) [jargon]:
phreaking
/freek'ing/, n.
[from `phone phreak']
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.