The ten-codes or ten-signals are code words used as stand-ins for common phrases in radio communication, such as ten-four, meaning message received. Charles Hopper, a communications director with the Illinois State Police, developed them in 1937 to combat the problem of the first syllables or words of a transmission being cut off or misunderstood. Preceding every code with “ten” gave the sometimes slow equipment time to warm up and improved the likelihood that a listener would understand the important part of a message. The codes also allowed for brevity and standardization in radio message traffic.
The codes were expanded by the Association of Public-Safety
Communications Officials-International (APCO) in 1974 and were
used by both law enforcement agencies and civilian CB radio users.
Over time, differing meanings for the codes came about in
different agencies and jurisdictions, undoing the codes’
usefulness as a concise and standardized system. The problem came
to a head in 2005 during rescue operations after Hurricane
Katrina. After several instances of inter-agency communication
problems, the United States Federal Emergency Management Agency
(FEMA) discouraged the use of ten-codes and today the federal
government recommends they be replaced with plain, everyday
In the days of the telegraph, the Morse code letter R
(dot-dash-dot) was sometimes used to indicate “received” or
“message received/understood.” When radio voice communication
began to replace telegraphs, Roger, the code word
assigned to the letter R in the Joint Army/Navy Phonetic
Alphabet (the radio alphabet used by all branches of the United
States military from 1941 to 1956), took on the same role.
Roger means “last transmission received/understood.” Wilco
(Will Comply) is the code used
if the speaker intends to convey “message received and will
comply.” The phrase Roger Wilco, often heard in the
movies, is redundant and not really used since Wilco alone
covers all the bases and acknowledges receipt of message and
states intent to comply.