TEN-CODES are code words used to represent common phrases in voice communication, particularly by law enforcement and and in Citizens' Band (CB) radio transmissions. The codes were developed in the 1930s to quickly and efficiently communicate across airwaves. 
Despite the long-standing tradition of ten-codes, police forces are dropping them. Problems occurred when departments joined forces during emergencies like 9-11 and the use of the codes created more inefficiencies than not.  Federal groups are now required to use plain language instead. 
Have no fear. We've still got it! Signing off...
10-4 good buddy!
 List of most common ten codes:
List of most common ten codes:
 
10-0  Use Caution 
10-1  Poor reception
10-2  Good reception 
10-3  Stop Transmitting 
10-4  Affirmative
10-5  Relay Message 
10-6  Busy with call 
10-7  Out of service
10-8  In service 
10-9  Repeat last message
For more, see news clip here.
Photo: 1977 Cobra 40 Channel CB Radio original advertisement. 
PUNCH AND BEAUTY... What a great slogan for Ten4 DS!
"It has what it takes to improve communications by punching through loud and clear... And that's the beauty of it." 
This vintage ad from the seventies is a perfect image for this post. You can purchase the vintage ad 
here.