What does 10-20 mean?

• A. Out of service; not available.
• B. In service; you are available for calls.
• C. Arrived at the scene.
• D. Location; report your current location or the scene location.

Answer: (D)

The main idea here is that 10-20 is a location code. In radio communications, units use 10-20 to ask for or report their current location or the location of the scene. Knowing where you are and where the incident is helps the dispatcher coordinate units, assign responders, and keep everyone safe. That’s why the option describing location is the best fit. The other ideas describe status or arrival—being in service or on scene—which are important updates but not what 10-20 itself represents. 10-20 specifically anchors the conversation to where you are or where the event is happening.