In the early days of police band radio, it took the transmitting device a fraction of a second to fully power up. This would often result in the first word spoken being partially cut off if the user didn’t remember to pause first after pressing the button. To solve this problem, the attention word “ten” was spoken first, followed by a “ten code” that identified the nature of the transmission. The codes were created by a state police employee from Illinois district ten, from which they take their name. They were adopted by citizens band radio enthusiasts in the seventies, and made popular by police shows on television and the hit song “Convoy” in 1975. The official list of codes ranges from 10-0 (“caution”) to 10-99 (“wanted”), with the most recognized and widely used one being 10-4 (“acknowledged”). While many of the codes are still in wide use, regional variations in meaning have resulted in confusion, reducing their effectiveness. Also, radio technology long ago eliminated the loss of initial syllables, and it has been recommended in recent years that the codes be abandoned in favor of plain language. They did this with the” Convoy” song title, which could have been called “10-59” (“convoy”). But that never would have been a hit.
* 10-43 = “Information”