California Police 10 Codes: The Ultimate 2026 Radio Decryption Guide
This guide decodes the standardized radio signals, California Highway Patrol (CHP) ten-codes, and state penal codes used by law enforcement agencies across California. Whether you are a public safety enthusiast, a journalist, or a scanner hobbyist, understanding these signals is essential for interpreting active radio traffic.
Understanding California's Dual Radio Language: 10-Codes vs. Penal Codes
Radio communication among California law enforcement agencies is unique due to its reliance on a hybrid system. Unlike states that use standard ten-codes for every event, California agencies blend three distinct verbal shorthand systems: standard ten-codes, California Penal Code sections, and California Vehicle Code sections.
The California Highway Patrol relies heavily on a structured set of traditional 10-codes to maximize radio efficiency and keep airtime clear. Conversely, municipal agencies like the Los Angeles Police Department (LAPD), San Francisco Police Department (SFPD), and various County Sheriff departments frequently bypass ten-codes for specific crimes. Instead, they broadcast the state penal code numbers directly. For example, rather than using a 10-code for a robbery in progress, a dispatcher will broadcast a "211 in progress."
Understanding this dual-system architecture is vital. If you only memorize traditional 10-codes, you will miss more than half of the operational transmissions broadcast by local police and sheriff dispatchers across the state.
Official California Highway Patrol (CHP) 10-Code Reference Table
The California Highway Patrol utilizes a highly disciplined 10-code system. Because CHP officers patrol thousands of miles of state highways and assist local municipal agencies, these codes serve as the foundational standard for statewide traffic safety and emergency response communications.
| 10-Code | Standard Operational Meaning | Practical Field Application |
|---|---|---|
| 10-1 | Poor receiving conditions | Used when static or interference prevents clear copy. |
| 10-2 | Good receiving conditions | Confirms the transmission is loud and clear. |
| 10-4 | Acknowledged / Understood | General receipt of message or directive. |
| 10-6 | Busy, stand by | Officer or dispatcher is occupied and cannot take traffic. |
| 10-7 | Out of service | Officer is off-duty or unavailable for calls. |
| 10-8 | In service | Officer is active, on patrol, and available for dispatch. |
| 10-9 | Repeat transmission | Requests the sender to broadcast the message again. |
| 10-10 | Off-duty | Officer has completed their shift. |
| 10-15 | Prisoner in custody | Confirms an arrest has been made and transport is starting. |
| 10-19 | Return to station | Instructs the unit to travel back to the local precinct or office. |
| 10-20 | Location requested | Asking for the current coordinates or street address of a unit. |
| 10-21 | Telephone call | Requesting the officer make a phone call to dispatch or a supervisor. |
| 10-22 | Cancel last assignment | Tells the responding unit to disregard the previous call. |
| 10-23 | Arrived at scene | Used in some jurisdictions; CHP often uses 10-97 instead. |
| 10-28 | Registration check | Requesting vehicle registration verification via state databases. |
| 10-29 | Wants/Warrants check | Requesting a database search for stolen status or active warrants. |
| 10-35 | Confidential information | Warning that sensitive details should not be broadcast over open air. |
| 10-36 | Correct time | Direct request or confirmation of the official system time. |
| 10-39 | Message delivered | Confirms that a requested contact or notification has been made. |
| 10-97 | Arrived at scene | Universal California indicator that the unit is on-site. |
| 10-98 | Finished with assignment | Unit has cleared the call and is ready for next dispatch. |
Police Code 197 - California Police Radio Codes - DMYDID
Common California Penal and Vehicle Codes Used on Police Radio
Municipal police departments and sheriff's deputies in California rely on numerical statutes from the California Penal Code (PC) and Vehicle Code (VC) to describe crimes and traffic incidents over the airwaves. Memorizing these key codes is critical for anyone monitoring local law enforcement dispatch channels.
- 187 PC: Homicide. This code refers to the unlawful killing of a human being or fetus with malice aforethought.
- 211 PC: Robbery. Used to report the taking of personal property in the possession of another, from their person or immediate presence, against their will, accomplished by means of force or fear.
- 240 PC / 242 PC: Assault and Battery. 240 PC denotes an unlawful attempt to commit a violent injury, while 242 PC confirms the actual, willful use of force or violence upon another.
- 245 PC: Assault with a Deadly Weapon (ADW). This indicates an assault committed with any deadly weapon or by means of force likely to produce great bodily injury.
- 273.5 PC: Domestic Violence. Specifically deals with corporal injury inflicted on a spouse, cohabitant, or fellow parent resulting in a traumatic condition.
- 314 PC: Indecent Exposure. Broadcast when an individual willfully and lewdly exposes their person or private parts in a public place.
- 415 PC: Disturbance / Fight. One of the most common calls broadcasted, indicating a public disturbance, loud noise, or physical altercation.
- 459 PC: Burglary. Entering a commercial or residential structure with the intent to commit a grand or petty larceny or any felony.
- 484 PC / 487 PC: Theft. 484 PC represents general petty theft (property valued under $950), while 487 PC denotes grand theft (property valued over $950).
- 10851 VC: Stolen Vehicle. The California Vehicle Code section for taking or driving a vehicle without the owner's consent.
- 23152 VC (historically referred to as 502): Driving Under the Influence. While legally 23152 VC, dispatcher and officer shorthand often still refers to a suspected drunk driver as a "502" or "DUI driver."
- 5150 WIC: Welfare and Institutions Code. Indicates an individual experiencing a mental health crisis who is deemed a danger to themselves, a danger to others, or gravely disabled.
Plain Language Transition vs. 10-Code Longevity in 2026
Modern radio standards have faced significant restructuring over the last two decades. The Federal Emergency Management Agency (FEMA) and the Department of Homeland Security strongly advocate for the complete elimination of ten-codes in favor of "Plain Language" (often called Common Terminology). This push is structured under the National Incident Management System (NIMS) and the Incident Command System (ICS).
The primary driver behind this transition is interoperability. During major multi-agency mutual aid events—such as the massive wildland-urban interface fires, earthquakes, or multi-jurisdictional tactical operations that California faces—first responders from CHP, local sheriff departments, CAL FIRE, and federal agencies must communicate seamlessly. If a CHP officer uses "10-39" to mean a message was delivered, but an out-of-state federal officer interprets it differently, it creates dangerous operational confusion.
Despite these federal guidelines, ten-codes and penal code abbreviations remain deeply entrenched in daily dispatch operations throughout California. Local agencies cite several reasons for their survival:
- Brevity and Speed: Saying "211" or "10-97" takes a fraction of a second, whereas saying "Robbery in progress" or "We have arrived on scene" takes longer, consuming valuable airtime on busy trunked radio systems.
- Operational Security: While scanner traffic is public, using shorthand numbers offers a minor layer of privacy against casual civilian eavesdropping, preventing immediate panic in public spaces.
- System Habit: Veteran dispatchers and patrol officers can process numerical codes instantly, finding the auditory patterns of structured codes easier to parse through heavy static or chaotic background noise.
How to Listen: Scanner Technology and Radio Encryption Realities
For decades, monitoring police dispatch required a simple analog crystal or programmable scanner. As municipal and state networks have advanced, listening to California police communications requires sophisticated hardware and an understanding of modern digital trunked radio networks.
Most metropolitan regions in California—including Los Angeles, San Diego, Orange County, and the San Francisco Bay Area—have migrated away from traditional VHF/UHF analog frequencies. Instead, they utilize Project 25 (P25) Phase I and Phase II digital trunked systems. To monitor these agencies, listeners must use a digital scanner capable of trunktracking and decoding P25 digital voice packets.
Operational Note on Encryption and Privacy Laws In compliance with security directives issued by the California Department of Justice, local law enforcement agencies have systematically evaluated their radio transmission security. Under these mandates, agencies must protect personally identifiable information (PII) and criminal history data transmitted over the air.
This regulatory environment has resulted in two distinct approaches among California law enforcement:
- Full Encryption: Many municipal departments have opted to encrypt all dispatch and tactical radio traffic. For these agencies, public monitoring via traditional physical scanners or online streaming apps is no longer possible.
- Selective Encryption: Other agencies maintain unencrypted primary dispatch channels to preserve transparency and public access, but immediately switch to fully encrypted tactical and inquiry channels when running database checks (10-29 checks) or conducting high-risk operations.
If you are attempting to program a scanner to listen to California agencies, you must verify the P25 talkgroup configurations and ensure your hardware supports the specific digital trunking standard used by your local county or city joint-powers communications authority.
Frequently Asked Questions About California Police Radio Codes
What does 10-4 mean in California?
10-4 is the universal law enforcement radio code for "Acknowledgment" or "Message Understood." It is used by both dispatchers and field officers to confirm they have received and comprehended the previous transmission.
Why do California police use codes like 5150 and 211 instead of 10-codes?
California agencies utilize state statutory codes (Penal Codes and Welfare & Institutions Codes) directly on the radio because they are precise and universally understood by local legal and judicial systems. Using "211" specifically designates a robbery, which is legally distinct from a simple theft or burglary, providing immediate clarity to responding units.
Is it legal to listen to police scanners in California?
Yes, it is generally legal for citizens to listen to unencrypted police scanner traffic on physical scanners or mobile applications. However, California Penal Code Section 636.5 makes it a misdemeanor to intercept public safety radio communications for the purpose of assisting in the commission of a crime or escaping from police action.
What is the difference between CHP codes and local police codes?
The California Highway Patrol uses a standardized, highly structured set of 10-codes optimized for highway safety, vehicle stops, and traffic enforcement. Local municipal police departments and county sheriffs use a blended system that relies less on complex 10-codes and more on California Penal Code and Vehicle Code section numbers.
Are California police departments phasing out 10-codes?
While federal NIMS and ICS guidelines encourage the adoption of plain language for mutual aid incidents, many California agencies maintain their historical 10-codes and penal codes for day-to-day dispatch operations due to their speed, brevity, and operational familiarity.
Technical Resources and Scanner Calibration
For those looking to configure P25 digital scanners, maintaining accurate frequency step sizes and trunking parameters is essential. When programming systems like the Los Angeles Regional Interoperable Communications System (LA-RICS) or the San Diego County Imperial County Regional Communications System (RCS), always ensure your scanner firmware is updated to support the latest TDMA (Phase II) modulation standards. Keeping your talkgroup databases synchronized with regional frequency coordinators ensures clear, uninterrupted reception of non-encrypted public safety dispatches.
