Police radio codes are numerical shorthand that officers and dispatchers use to pass information quickly over limited airtime. The main families are the APCO 10-codes for status and requests, “Code” numbers (Code 1, 2, 3) that set how urgently a unit responds, 11-codes used mostly in California for specific field incidents, and penal-code numbers that stand in for named offenses. Meanings are not uniform nationwide, so the same digits can carry different definitions from one agency to the next.
What the Common 10-Codes Mean
The 10-code system is the one most people recognize. A core set is used, in some form, by most U.S. law enforcement agencies:
- 10-4: Message received and understood.
- 10-6: Busy, stand by.
- 10-7: Out of service (end of shift or off the air).
- 10-8: In service, available for assignment.
- 10-9: Repeat your last transmission.
- 10-20: What is your location? Also used to report one (“My 10-20 is Fifth and Main”).
- 10-23: Arrived at scene.
- 10-27: License or registration check.
- 10-29: Check for warrants.
- 10-33: Emergency in progress; clear the channel for critical traffic.
- 10-42: Welfare check on an officer or person at a location.
- 10-76: En route to a call.
- 10-99: Wanted or stolen vehicle in many jurisdictions; officer in distress in others.
These are the most common APCO-aligned versions. A 10-99 in one city may mean something very different in another, which is the key limitation of the system: it feels standardized but isn’t.
Response Priority Codes: Code 1, Code 2, and Code 3
Separate from 10-codes, most agencies use a priority “Code” to tell responding officers how urgently to travel.
- Code 1: Respond at your convenience. No urgency. Used for routine calls with no active threat.
- Code 2: Urgent, but no lights and sirens. Get there promptly while following normal traffic laws.
- Code 3: Emergency response with lights and sirens. Reserved for immediate danger to life or a violent crime in progress.
Dispatchers assign the priority from what a caller reports. An overnight break-in at an empty house might go out as Code 1; a domestic disturbance with screaming in the background goes out as Code 3. The distinction matters because Code 3 driving carries real risk, and agencies face liability when officers run lights and sirens for calls that don’t warrant them.
11-Codes (Mostly California)
The 11-code system is most closely tied to California law enforcement, particularly the California Highway Patrol and the Los Angeles Police Department. If you hear 11-codes on a scanner, you are almost certainly listening to a California-area agency. They fill gaps the 10-codes don’t cover well, especially around traffic incidents:
- 11-10: Take a report.
- 11-24: Abandoned vehicle.
- 11-41: Ambulance needed.
- 11-44: Deceased person (coroner’s case).
- 11-54: Suspicious vehicle.
- 11-80: Traffic collision with major injuries.
- 11-82: Traffic collision with no injuries.
- 11-97: Time and security check on a patrol unit.
- 11-99: Officer needs emergency help.
The split between 11-80 and 11-82 is operational: 11-80 tells fire and EMS to roll with patrol, while 11-82 means traffic control and a report but no ambulance.
Penal Code Numbers Used on the Radio
Officers also use numerical shorthand for specific offenses, often pulled straight from a state’s penal code. The widely recognized examples come from the California Penal Code, where the section number doubles as the radio call:
- 187: Homicide.
- 211: Robbery.
- 242: Battery.
- 459: Burglary.
- 484/488: Petty theft.
- 502: Driving under the influence.
These numbers are not universal. “211 in progress” means robbery in California, but a Texas or Ohio agency references its own statutes with different numbers. To decode what you hear on a scanner, you need to know which state’s codes the agency is using.
Phonetic Alphabets
When officers spell out a plate, name, or case number, they use a phonetic alphabet so similar-sounding letters don’t get confused. “B as in Boy” is unambiguous in a way that a bare “B” isn’t over a noisy radio.
Two systems are in common use. The APCO phonetic alphabet uses everyday names: Adam, Boy, Charles, David, Edward, Frank, George, Henry, and so on. Many local and state agencies use it for daily patrol. The NATO phonetic alphabet uses a different word set: Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, and so on. NATO developed it in 1956, and it became the international standard for aviation and maritime communication as well.1NATO. The NATO Phonetic Alphabet
In multi-agency events involving federal, military, or international partners, NATO usually takes over because it is what everyone outside local policing already knows. Some departments have switched to NATO entirely; others keep APCO internally and switch to NATO for joint operations.
Why Meanings Vary and Why Plain Language Is Replacing Codes
APCO published a standard 10-code list, but it was never enforced as a single national standard. Agencies adopted the framework and customized it, which is why the same code can mean different things in neighboring counties. The problem gets worse when police, fire, and EMS respond to the same scene using different code systems.
FEMA’s National Incident Management System (NIMS) now requires plain language for any multi-agency, multi-jurisdiction, or multi-discipline event, including major disasters and training exercises. Plain language means saying “I’m on scene” instead of “10-23,” or “send an ambulance” instead of “11-41.” NIMS does not force agencies to abandon 10-codes for their own routine, internal traffic, and keeping codes for daily patrol will not cost a department federal preparedness funding.2Federal Emergency Management Agency. NIMS Alert – NIMS and Use of Plain Language The guidance still encourages plain language internally, because officers who use coded shorthand every day tend to revert to it under stress.
Most departments now run in a hybrid mode: familiar 10-codes for routine patrol, plain speech when outside agencies are involved. Codes aren’t disappearing, but the trend favors plain language.
Listening on a Scanner: Legality and Encryption
If you are trying to understand codes because you listen to a scanner, two legal points matter. Under federal law, listening to unencrypted police radio is legal. The Wiretap Act exempts the interception of radio communications transmitted by government and law enforcement entities that are “readily accessible to the general public.”3Office of the Law Revision Counsel. 18 USC 2511 – Interception and Disclosure of Wire, Oral, or Electronic Communications Prohibited State laws add complications. Roughly a dozen states restrict scanner possession in vehicles, and about ten more increase penalties when a scanner is used to help commit a crime. In states with vehicle restrictions, a working scanner in your car during a traffic stop can lead to misdemeanor charges, fines, or impoundment, even without any illegal use. Check your state’s statute before putting a mobile scanner in your car.
The larger practical change is encryption. Departments across the country have moved to encrypted digital radio, and a standard scanner picks up nothing from those systems. Some agencies encrypt only tactical and undercover channels and leave routine dispatch open.4Federal Emergency Management Agency. NIMS Alert 06-09 – NIMS and Use of Plain Language Where channels are fully encrypted, no code list will help you decode what you can’t hear. The codes above are most useful for agencies still broadcasting on open frequencies, for following references in news coverage and procedural media, and for anyone studying or entering law enforcement.