Police radio codes, also known as "10 codes," are assigned numbers used to transmit information between police officers and the dispatch center. The "10" is a prefix, indicating that the following numbers are a coded message. The codes transmit information such as an officer's status and location.
The 10 codes can vary between police departments, but a few are universal. For example, "10-8" means the officer is in service and on the way to a call. "10-7" indicates that officer is available. "10-4" stands for message received. Asking an officer his "10-20" means you want his location. An officer noting "10-19" is returning to police headquarters.
Codes can also be used to transmit or obtain information. An officer can ask for a "10-21" which means he wants you to call someone on a land line. The phone number, if obtained at the scene, is transmitted after the code. If an officer is on a traffic stop, he may ask for a "10-28." This is a request for vehicle registration information.
Other 10 codes are used to indicate crimes or problems. A "10-80" indicates an officer is chasing a suspect, while "10-93" means the officer has set up a roadblock. Anyone who is pulled over and hears the officer start talking about a "10-31" should be prepared to take a breathalyzer test.