A wire signal is a brevity code used by telegraphers to save time and cost when sending long messages. The most well-known of these was the 92 Code adopted by Western Union in 1859. The reason for this adoption was to reduce bandwidth usage over the telegraph lines and speed transmissions by utilizing a numerical code system for various frequently used phrases. 
Several of the codes are taken from The Telegraph Instructor by G.M. Dodge. Dodge notes:
- Other numerical signals are used by different railroads for different purposes, for instance, the signal “47” upon some railroads means “display signals”; while the signal “48” means “signals are displayed”. The numerals “9” and “12” are frequently used for “correct”. Other numerals are used for the different officials’ messages, agents’ messages, etc.
Codes that are not listed in the 1901 edition of Dodge are marked with an asterisk (*).
|1||* Wait a minute.||25||Busy on another wire.|
|2||Very Important.||26||* Put on ground wire.|
|3||* What time is it?||27||* Priority, very important.|
|4||Where shall I go ahead?||28||* Do you get my writing?.|
|5||Anything? (Have you business for me?)||29||* Private, deliver in sealed envelope.|
|6||* I am ready.||30||* No more - the end.|
|7||* Are you ready?||31||Form 31 train order.|
|8||Close your key, stop breaking.||32||* I understand that I am to ....|
|9||* Priority business. Wire Chief's call.||33||Answer is paid.|
|10||* Keep this circuit closed.||34||* Message for all officers.|
|12||* Do you understand?||35||* You may use my signal to answer this.|
|13||Understand?||37||* Inform all interested.|
|14||* What is the weather?||39||* Important, with priority on through wire.|
|15||* For you and others to copy.||44||* Answer promptly by wire.|
|17||* Lightning here.||55||Important.|
|18||What's the trouble?||73||Best Regards.|
|19||Form 19 train order.||77||* I have a message for you.|
|21||* Stop for meal.||88||* Love and kisses.|
|22||Wire test.||91||* Superintendent's signal.|
|23||* All stations copy.||92||Deliver Promptly.|
|24||* Repeat this back.||134||* Who is at the key?|
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.
Today, amateur radio operators still use codes 73 and 88 profusely, 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." The other codes have mostly fallen into disuse.
1873 Telegraph Rules from the Lakeshore and Tuscarawas Valley Railway Company
|1||Wait a minute.|
|3||Give me the correct time|
|4||Where shall I go ahead?|
|5||Have you anything for me?|
|6||I have a message for you.|
|7||I have a message for you.|
|8||What is the matter?|
|9||Very important business; must take precedence.|
|10||Keep circuit closed.|
|12||How do you understand this?|
|13||I (or we) understand—|
|15||Inform all interested.|
|19||Ready for business.|
|20||Repeat this back to me.|
|22||Busy on other circuit.|
|23||Have you report of—|
|24||My instrument works badly.|
|25||Did you get my writing?|
|134||Who is at the key?|
- Stuttgart Telegraph Convention 1857 between states of the Austro-Germanic Union. official title "Revised Convention of the Austro-German Telegraph Union, Stuttgart, 3 October 1857, 118 CTS5"? ("Service Instructions" section)
- Radiotelegraph and Radiotelephone Codes, Prowords And Abbreviations
- International Communications: The International Telecommunication Union and Universal Postal Union (page 19)
- Western Union and the Creation of the American Corporate Order, 1845-1893 By Joshua D. Wolff
- The Western Union Telegraph Company, rules, regulations, and instructions
- Wood's Plan of Telegraphic Instruction
- On the Origin of 73
- 88, Or How Telegraphers Coded 'Love and Kisses'
- The Phillips Code
- ORIGIN OF HAM SPEAK - FACT, LEGENDS AND MYTHS???
- Ham Speak - Know the Lingo
- SignalHarbor: 73 speak
- The Telecommunications Illustrated Dictionary, Second Edition
- telegraphic and signal codes: annotated directory of scans, transcriptions : notes
- Nonsecret Code: An Overview of Early Telegraph Codes
- Cipher and telegraph codes
- "1859 Western Union "92 Code" & Wood's 1864 "Telegraphic Numerals" & Comparison of Alphabetic Telegraph Codes". Retrieved 2008-11-23.
- Dodge, G.M. (1901). The telegraph instructor. Valparaiso, Ind.: Not Given. p. 50.
- "Women in amateur radio - Amateur-radio-wiki". www.amateur-radio-wiki.net. Retrieved 2016-08-01.
- "Telegraph Rules: Adopted October 1, 1873 By Lake shore and Tuscarawas valley railway company". 1873.