Ten-codes, or 10-codes, are used in two-way voice radio communication as numeric codewords for frequently used messages. They originated in the United States law enforcement community before World War II. There is no universal, official set of 10-codes, and the meanings of a particular 10-code can vary between one jurisdiction and another: a code meaning "I have the suspect in custody" in one state can mean "Send an ambulance" in a second state and have yet another meaning in a third.
Ten-codes were adopted with enthusiasm by the Citizen's Band craze, first in the US, then shortly afterwards in the UK and elsewhere. The codes were extended and changed to reflect the sorts of things that CBers wanted to refer to, rather than law enforcement usage, etc. During the height of the fad in the UK (around 1980), new ten codes were seemingly made up on the spot, used in the local area for a short time, then disappeared again.
The following is a sample of commonly used 10-codes, submitted for purposes of illustration. It is common for a 10-code to have numeric gaps.
- 10-1 Poor reception
- 10-2 Good reception
- 10-4 Message received
- 10-5 Relay this information to ___.
- 10-6 Busy
- 10-7 Out of service
- 10-8 In service
- 10-9 Please repeat your message
- 10-13 Civilians present and listening
- 10-15 Enroute to station with suspect
- 10-19 Return to station
- 10-20 Specify location/My location is ___.
- 10-21 Place a phone call to ___.
- 10-22 Disregard
- 10-23 Stand by on this frequency
- 10-33 Emergency traffic follows. Hold routine messages.
- 10-34 Frequency open (cancels 10-33)
- 10-36 What is the correct time of day?
- 10-39 False alarm, premises was occupied
- 10-40 False alarm, no activity, premises appears secure
- 10-41 Begin watch
- 10-42 End watch
- 10-45 Fueling vehicle
- 10-49 Enroute to assignment
- 10-60 Specify time complainant called
- 10-97 Arrival at assignment location
- 10-98 Departing assignment location
