Police scanner codes: 10-codes and plain language
Radio codes exist to keep transmissions short and consistent. The catch for a listener is that they are not standard: 10-50 means one thing in one county and something else in the next, which is exactly why many agencies have abandoned them.
The codes most people recognise
A handful are common enough to be worth knowing, though even these vary.
| Code | Usual meaning |
|---|---|
| 10-4 | Acknowledged, understood |
| 10-8 | In service, available |
| 10-7 | Out of service, unavailable |
| 10-20 | Location |
| 10-97 | Arrived on scene |
| 10-23 | Stand by |
| Code 4 | No further assistance needed, scene under control |
Treat every one of these as local. The same number can mean something completely different one jurisdiction over, and a confident list found online is often a list for somewhere else.
Why departments moved to plain language
Coded speech works when everyone shares the same code book. It fails badly when they do not, and large incidents are exactly when agencies who never work together suddenly share a channel. After several major incidents where mismatched codes caused genuine confusion, national guidance in the United States pushed responders toward plain language for multi agency events, and many departments went further and dropped codes entirely.
For a listener this is good news. Plain language is easier to follow and needs no lookup table.
Things you will hear besides codes
- Unit identifiers. Usually a district or beat plus a number. Following one unit through a shift teaches you a system faster than any code list.
- The phonetic alphabet. Alpha, Bravo, Charlie and so on, used for letters in names and plates.
- Priority or response levels. Often a number describing how urgent a call is, or whether lights and sirens are authorised.
- Signals. Some agencies use "Signal" plus a number in place of 10-codes. Same idea, same locality problem.
- Dispatch tones. Fire and EMS often use alert tones before a dispatch, which is a useful cue that something is starting.
How to follow a call without memorising anything
- Listen for the address first. Almost every dispatch includes a location, and that anchors everything else.
- Track the unit. Once a unit is assigned, its later transmissions belong to the same story.
- Wait for the disposition. Calls usually end with a status: nothing found, report taken, someone transported.
- Use context over vocabulary. You will infer what a code means from what happens after it, and that knowledge is correct for your area rather than someone else's.
Finding the right list for your area
If your local agencies still use codes, the reliable sources are the agency's own published policy where one exists, and local scanner communities, who tend to keep accurate lists for their own patch. A generic list of "police codes" is a rough guide at best.
New to this? Start with how scanners work.
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