Last updated: March 2026
Police scanner codes — also called 10-codes — are standardized shorthand used by law enforcement, fire, and EMS over radio. Whether you’re monitoring a police scanner app to stay informed about neighborhood safety, or you just want to understand what you hear on emergency radio, this is the complete reference.
We also cover how scanner monitoring fits into a broader home security strategy — because knowing what’s happening around you is the first layer of protection.
What Are Police 10-Codes?
Developed in 1937 by the Association of Public-Safety Communications Officials (APCO), 10-codes were designed to:
- Keep radio transmissions short and efficient
- Reduce misunderstandings on noisy analog radio channels
- Provide some privacy from public scanner listeners
- Standardize communication across departments
Important note: After Hurricane Katrina (2005), the Department of Homeland Security recommended agencies switch to plain language because 10-codes varied between departments. Many agencies have switched, but 10-codes are still widely used — especially by local police and in rural areas.
| Code Type | Used By | Example | Still Common? |
|---|---|---|---|
| APCO 10-Codes | Local police, sheriff, some fire | 10-4 (acknowledged) | Yes — most common |
| NYPD 10-Codes | New York City PD | 10-13 (officer needs help) | Yes — NYC specific |
| California Penal Codes | California law enforcement | 187 (homicide), 459 (burglary) | Yes — CA specific |
| Signal Codes | Some southern US departments | Signal 7 (dead person) | Declining |
| Plain Language | Federal agencies, many modern departments | “Copy that” instead of “10-4” | Growing |
Complete Police 10-Code Reference
Communication & Status Codes (10-1 through 10-12)
| Code | Meaning | When You Hear It |
|---|---|---|
| 10-1 | Unable to copy / Poor reception | Bad radio signal |
| 10-2 | Signal good / Clear reception | Confirming good connection |
| 10-3 | Stop transmitting | Channel needs to be cleared |
| 10-4 | Acknowledged / Message received | Most common code — “understood” |
| 10-5 | Relay message | Pass info to another unit |
| 10-6 | Busy / Stand by | Officer occupied, can’t respond right now |
| 10-7 | Out of service | Officer going off duty or on break |
| 10-8 | In service | Officer available for calls |
| 10-9 | Repeat last transmission | Didn’t hear clearly |
| 10-10 | Fight in progress | Active altercation |
| 10-11 | Dog case / Animal complaint | Animal-related call |
| 10-12 | Stand by / Visitors present | Can’t talk freely |
Emergency & Priority Codes (10-13 through 10-39)
| Code | Meaning | Priority Level |
|---|---|---|
| 10-13 | Weather/road report (NYPD: Officer needs assistance) | ⚠️ High (NYPD version) |
| 10-14 | Report of prowler | ⚠️ Medium |
| 10-15 | Civil disturbance | Medium |
| 10-16 | Domestic problem | ⚠️ Medium-High |
| 10-17 | Meet complainant | Low |
| 10-18 | Quickly / Urgent | ⚠️ High |
| 10-19 | Return to station | Low |
| 10-20 | Location / “What’s your 20?” | Informational |
| 10-21 | Call by telephone | Low |
| 10-22 | Disregard / Cancel | Low |
| 10-23 | Arrived at scene | Informational |
| 10-24 | Assignment completed | Informational |
| 10-25 | Report in person | Low |
| 10-26 | Detaining suspect | Medium |
| 10-27 | Driver’s license information | Informational |
| 10-28 | Vehicle registration information | Informational |
| 10-29 | Check for wants/warrants | Medium |
| 10-30 | Unnecessary use of radio | Low |
| 10-31 | Crime in progress | 🔴 High |
| 10-32 | Person with gun | 🔴 Critical |
| 10-33 | Emergency — all units stand by | 🔴 Critical |
| 10-34 | Riot | 🔴 Critical |
| 10-35 | Major crime alert | 🔴 High |
| 10-36 | Correct time | Informational |
| 10-37 | Suspicious vehicle | Medium |
| 10-38 | Stopping suspicious vehicle | ⚠️ Medium |
| 10-39 | Urgent — use lights and siren | 🔴 High |
Property & Crime Codes (10-40 through 10-69)
| Code | Meaning | Relevant to Home Security? |
|---|---|---|
| 10-40 | Silent run — respond without siren | ✅ Often for burglary in progress |
| 10-41 | Beginning tour of duty | |
| 10-42 | Ending tour of duty | |
| 10-43 | Information | |
| 10-44 | Permission to leave | |
| 10-45 | Dead animal | |
| 10-46 | Assist motorist | |
| 10-47 | Emergency road repair needed | |
| 10-48 | Standard traffic stop | |
| 10-49 | Traffic light out | |
| 10-50 | Accident (property damage) | |
| 10-51 | Wrecker needed | |
| 10-52 | Ambulance needed | ✅ Medical emergency |
| 10-53 | Road blocked | |
| 10-54 | Livestock on highway | |
| 10-55 | Intoxicated driver | |
| 10-56 | Intoxicated pedestrian | |
| 10-57 | Hit and run | |
| 10-58 | Direct traffic | |
| 10-59 | Convoy or escort | |
| 10-60 | Squad in vicinity | |
| 10-61 | Isolate self for message | |
| 10-62 | Reply to message | |
| 10-63 | Prepare written copy | |
| 10-64 | Message for local delivery | |
| 10-65 | Net message assignment | |
| 10-66 | Message cancellation | |
| 10-67 | Clear to read message | |
| 10-68 | Dispatch information | |
| 10-69 | Message received |
Alarm & Response Codes (10-70 through 10-99)
| Code | Meaning | Relevant to Home Security? |
|---|---|---|
| 10-70 | Fire alarm | ✅ Fire/smoke detector triggered |
| 10-71 | Advise nature of fire | ✅ |
| 10-72 | Report progress of fire | ✅ |
| 10-73 | Smoke report | ✅ |
| 10-74 | Negative / No | |
| 10-75 | In contact with… | |
| 10-76 | En route | ✅ Officers responding to your call |
| 10-77 | ETA (Estimated Time of Arrival) | ✅ |
| 10-78 | Need assistance | ⚠️ |
| 10-79 | Notify coroner | |
| 10-80 | Chase in progress | ⚠️ |
| 10-84 | If meeting, advise ETA | |
| 10-85 | Delayed | |
| 10-86 | Officer/operator on duty | |
| 10-87 | Pick up/distribute checks | |
| 10-88 | Present telephone number of… | |
| 10-89 | Bomb threat | 🔴 Critical |
| 10-90 | Bank alarm at… | ✅ Alarm response |
| 10-91 | Pick up prisoner/subject | |
| 10-92 | Improperly parked vehicle | |
| 10-93 | Blockade | |
| 10-94 | Drag racing | |
| 10-95 | Prisoner/subject in custody | ✅ Suspect caught |
| 10-96 | Mental subject | |
| 10-97 | Check signal (test) | |
| 10-98 | Prison/jail break | ⚠️ |
| 10-99 | Wanted/stolen indicated |
Codes You’ll Hear During Home Security Incidents
If your home security system triggers a professional monitoring dispatch, or you call 911, here’s what you might hear on a scanner:
| What Happened | Codes You’ll Hear | What It Means |
|---|---|---|
| Burglar alarm triggered | 10-31, 10-14, 10-40 | Crime in progress, prowler, responding silently |
| Officers en route to your home | 10-76, 10-77 | En route, estimated arrival time |
| Officers arrived | 10-23 | On scene |
| False alarm confirmed | 10-22, 10-24 | Disregard, assignment complete |
| Suspect detained | 10-26, 10-95 | Detaining suspect, in custody |
| Fire/smoke alarm | 10-70, 10-71 | Fire alarm, nature of fire |
| Medical emergency | 10-52 | Ambulance needed |
| Neighbor reported suspicious person | 10-14, 10-37 | Prowler, suspicious vehicle |
California Penal Codes (Used by CA Law Enforcement)
In California, officers often use penal code numbers instead of 10-codes:
| Code | Crime | Home Security Relevance |
|---|---|---|
| 187 | Homicide | |
| 211 | Robbery | ✅ Home invasion |
| 245 | Assault with deadly weapon | |
| 261 | Rape | |
| 415 | Disturbing the peace | |
| 459 | Burglary | ✅ Most common home security incident |
| 484/488 | Petty theft | ✅ Package theft |
| 487 | Grand theft | ✅ |
| 594 | Vandalism | ✅ Property damage |
| 602 | Trespassing | ✅ Trespasser on property |
| 647(h) | Prowling/loitering | ✅ Suspicious person near home |
Best Police Scanner Apps (2026)
| App | Platform | Cost | Coverage | Features |
|---|---|---|---|---|
| Broadcastify | iOS, Android, Web | Free (Premium $30/yr) | 7,000+ feeds nationwide | Live + 365-day archive (Premium), alerts |
| Scanner Radio | iOS, Android | Free (Pro $5) | 5,300+ feeds | Trending alerts, nearby feeds, notifications |
| 5-0 Radio | iOS | Free | 5,000+ feeds | Simple interface, background play |
| Police Scanner X | iOS, Android | Free | 4,000+ feeds | Favorites, background audio |
| Citizen | iOS, Android | Free (Premium $20/mo) | Major US cities | Real-time incident map, video, community alerts |
Scanner Monitoring + Home Security: A Layered Approach
Monitoring a police scanner can complement your home security system, but it shouldn’t replace one:
| Layer | What It Does | Response Time | Passive/Active |
|---|---|---|---|
| 1. Home security system | Detects intrusion, sounds siren, sends alerts | Instant (push notification) | Active — deters + alerts |
| 2. Security cameras | Records video, enables visual verification | Instant (live view) | Active — deters + documents |
| 3. Professional monitoring | Dispatches police/fire/EMS automatically | 30-60 seconds | Active — dispatches help |
| 4. Police scanner app | Hear police response to neighborhood incidents | Real-time audio | Passive — awareness only |
| 5. Community alerts (Citizen, Nextdoor) | Crowd-sourced incident reports | Minutes to hours | Passive — awareness only |
Key point: Scanner monitoring gives you awareness but not protection. A proper home security system with sensors, cameras, and monitoring provides actual protection. Use scanner apps as an awareness supplement, not a security system replacement.
False Alarm Codes & Why They Matter
One of the most common calls police respond to is false security alarms. Understanding how departments handle them can save you money:
| Issue | What Happens | How to Avoid |
|---|---|---|
| Unverified alarm dispatch | Police respond but find no crime — gets coded 10-22 (disregard) | Self-monitor with cameras to verify before calling 911 |
| Repeat false alarms | Many cities fine homeowners after 2-3 false alarms/year ($50-500 per incident) | Upgrade sensors, use geofencing to auto-arm correctly |
| Alarm permit required | Some cities require alarm registration ($25-100/year) | Check local requirements before installing |
| “Verified response” ordinances | Police won’t respond to unverified alarms — require video/audio confirmation | Use a system with cameras for visual verification |
Systems like Abode with integrated cameras let you visually verify an alarm before calling police — reducing false alarm fines and ensuring faster response when it’s real.
Frequently Asked Questions
Is it legal to listen to police scanners?
Yes, in all 50 US states it’s legal to listen to police scanner frequencies from a fixed location. However, some states (Florida, Indiana, Kentucky, Minnesota, New York) restrict using a scanner in a vehicle without a permit. Federal frequencies (FBI, DEA, Secret Service) are encrypted and cannot be monitored.
Are police switching away from 10-codes?
Yes, gradually. After 9/11 and Hurricane Katrina exposed communication failures between agencies using different code systems, the Department of Homeland Security recommended plain language. Federal agencies and many large departments have switched, but thousands of local departments still use 10-codes.
What does “10-4” actually mean?
“10-4” means “acknowledged” or “message received.” It’s the most widely known police code, entering mainstream culture through CB radio and TV shows. It does NOT mean “yes” — it simply confirms the message was heard.
How do police respond to home security alarms?
When a monitored alarm system triggers, the monitoring center contacts police dispatch, which assigns a priority level and dispatches officers. You’ll hear codes like 10-31 (crime in progress), 10-76 (en route), and 10-23 (arrived). If verified as false, 10-22 (disregard) and 10-24 (assignment complete).
Can scanners help me know if my neighborhood is safe?
Scanner monitoring gives you real-time awareness of police activity, but it’s reactive — you hear about incidents after they’ve started. For proactive protection, combine scanner awareness with a home security system, outdoor cameras, and motion-activated lighting.
What frequency do police use?
Most US police departments use UHF (450-470 MHz) or VHF (150-174 MHz) frequencies. Many have transitioned to digital/encrypted trunked systems (P25), which standard analog scanners can’t receive. Scanner apps like Broadcastify stream feeds from volunteers with digital-capable scanners.
Growing up with Law and Order and CSI shows taught Isabelle Landau one thing: if people back then had high-quality home security systems, those series would have been way shorter. In our modern world, technology helps us keep burglars away easily, and this is what Izzy studies and writes about: alarm systems, home security, protection systems, and more.
Camron Brown says
Given that one of the events in our role-playing exercise at school involves encounters with the police, I find this article to be really interesting. I suppose I will suggest that I play one of the police officers as this provides me with an idea of how to be one.
Jared says
This is interesting, I’ve seen several movies where they made use of this but I failed to appreciate it because I didn’t get their meanings. It sounds pretty cool once you understand the meanings as opposed to just thinking the police officer is just blurting out some random codes!
I’ve enjoyed learning new stuff on the blog and would love to read more on interesting yet informative posts like these.
James Smith says
Good to know some of the common codes and their uses. I skimmed through the list and saw some ones that I recognize. Do you think police officers know every code on this list… or just the popular ones? I wonder…
Matt G. says
Just saw the movie Nightcrawler where the main actor memorized the codes within a week or two. I wanted to see how many codes there actually are so this list proved useful. Thanks for sharing!
Blake Reeves says
Great write up. I recently downloaded a police scanner app on my iPhone and I can hear the police communicate and they use these codes. 10-4 is the most popular one and one I hear the most. I hope I never hear 10-74… (Prison Break) Good read!