What are the 10 codes?

Ten-codes were developed in the 1940s at a time when police radio channels were limited, to reduce use of speech on the radio. Ten-codes were later adapted for use by CB radio enthusiasts before its pop culture explosion in the late 1970s; thus, many of the phrases, such as 10-4 and "what's your twenty", have entered everyday use in the English language. Popular fictional accounts of ten-codes in use among CB-communicating truckers may be heard in the 1975 Convoy song by C.W. McCall, and the 1978 movie Convoy.