A wire signal is a brevity code used by telegraphers to save time and cost when sending long messages. The best-known code was the 92 Code adopted by Western Union in 1859. The code was designed to reduce bandwidth consumption over telegraph lines, thus speeding transmissions by utilizing a numerical code system for frequently used phrases.

92 Code

Several of the codes are taken from The Telegraph Instructor by G.M. Dodge. Dodge notes: Codes that are not listed in the 1901 edition of Dodge are marked with an asterisk (*). In the above list, the numbers 19 and 31 refer to train order operations whereby messages from the dispatcher about changes in railroad routing and scheduling were written on paper forms. Form 19 was designed to be passed to the train as it went through a station at speed. Form 31 required hand delivery for confirmation.

Contemporary usage

Today, amateur radio operators still use codes 73 and 88 regularly, and -30- is used in journalism, as it was shorthand for "No more - the end". The Young Ladies Radio League uses code 33 to mean "love sealed with friendship and mutual respect between one YL [young lady] and another YL" or simply "hugs." A once-used but unofficial code 99 meant "go to hell." The other codes have mostly fallen into disuse.

1873 Telegraph Rules from the Lakeshore and Tuscarawas Valley Railway Company

The following code was taken from 1873 telegraph rulebook of the Lakeshore and Tuscarawas Valley Railway Company of Cleveland, Ohio.