9-Code, 10-Code

Over the years, public safety dispatchers have developed a semi-standardized code for speaking on the radio. Although the trend during the past 10 years has been to use plain English for law enforcement and fire communications, many agencies still use codes on the radio. The code is known as “the ten code” because the actual code is preceded by the word “ten.” The origin and reason for this is unknown. However, it appears that the “ten” prefix was meant to signal that the numbers following are part of the code, and not an address, age, phone number, etc. Over the years, as more codes were added, the number of ten-codes ran out, and agencies began using “eleven” as a prefix. At some point, other agencies developed a nine-code that accomplished the same thing but used the number nine as a prefix.

The use of codes continues, despite some pressure to use plain English to assist in clarity and operations among different agencies. Once in a while a agency will announce they’re switching away from codes. But since many laws, ordinances and other regulations are stated in letter/number codes, many law enforcement agencies continue to use codes over-all.

We do know that the first published 10-Code was in the APCO Bulletin of January, 1940, after a meeting of the State Systems Standards Committee in Springfield (Ill.)–part of their Project 4 to develop developed “Ten Signal Cards.” There were only 17 codes in the first version, but it grew to about 60 after the list was first published. APCO also took a stab at standardizing codes back in 1973 as part of their Project 14 to make radio communications more concise. These codes includes those from 10-1 to 10-39, with an “optional” list of codes above 10-39. We don’t know of any original listing of these codes on the APCO Web site, but check here for the standard codes, and here for the expanded set.

In late 2005 FEMA established requirements for adoption of the National Incident Management System (NIMS), including a requirement that all public safety agencies routinely use plain English on the radio in order to qualify for any federal grants. However, after some hot debate, FEMA rescinded the order in Feb. 2006, saying plain English was only required when handling multi-agency, multi-jurisdictional incidents. Download (pdf) the explanatory letter.

In early 2009 several large agencies began the transition to plain English, including Dallas PD.

Despite attempts at standardization, there are probably 20 to 30 versions of the original 10-Code being used across the county. Even when an agency uses the standard list, they probably have customized a some of the codes for their own use. For each code we have tried to include the most common definitions. In this consolidated list, some codes have the same definition. Also, many agencies do not use all of the codes on this list, but rather just the few they need.

Many codes can be suffixed by the letter “x” to indicate that a female was involved, or other letters that specify more information (“A” for audible alarm, “S” for silent, etc.).

For this reason, it’s not advisable to memorize this list if you intend to study before becoming a dispatcher–your agency probable has its own list. However, it would be helpful to be familiar with the definitions and types of information that are usually condensed to code form.

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