The Jargon File (version 4.4.7, 29 Dec 2003):
hakspek
 /hak'speek/, n.
    A shorthand method of spelling found on many British academic bulletin
    boards and talker systems. Syllables and whole words in a sentence are
    replaced by single ASCII characters the names of which are phonetically
    similar or equivalent, while multiple letters are usually dropped. Hence,
    ?for? becomes ?4?; ?two?, ?too?, and ?to? become ?2?; ?ck? becomes ?k?. ?
    Before I see you tomorrow? becomes ?b4 i c u 2moro?. First appeared in
    London about 1986, and was probably caused by the slowness of available
    talker systems, which operated on archaic machines with outdated operating
    systems and no standard methods of communication.
    Hakspek almost disappeared after the great bandwidth explosion of the early
    1990s, as fast Internet links wiped out the old-style talker systems.
    However, it has enjoyed a revival in another medium ? the Short Message
    Service (SMS) associated with GSM cellphones. SMS sends are limited to a
    maximum of 160 characters, and typing on a cellphone keypad is difficult
    and slow anyway. There are now even published paper dictionaries for SMS
    users to help them do hakspek-to-English and vice-versa.
    See also talk mode.
The Free On-line Dictionary of Computing (30 December 2018):
hakspek
    /hak'speek/ A shorthand method of spelling found on
   many British academic bulletin boards and chat systems.
   Syllables and whole words in a sentence are replaced by single
   ASCII characters the names of which are phonetically similar
   or equivalent, while multiple letters are usually dropped.
   Hence, "for" becomes "4"; "two", "too", and "to" become "2";
   "ck" becomes "k".  "Before I see you tomorrow" becomes "b4 i c
   u 2moro".  First appeared in London about 1986, and was
   probably caused by the slowness of available talk systems,
   which operated on archaic machines with outdated operating
   systems and no standard methods of communication.  Has become
   rarer since.
   See also chat, B1FF, ASCIIbonics.
   [Jargon File]
   (1998-01-25)