In APCO, Association of Public-Safety Communications Officials 10-codes, 10-40 means "Silent / No Calls" or "Out of Service". It is used to indicate that a unit is temporarily unavailable for dispatch, clearing radio traffic, or taking a break, allowing dispatch and other units to adjust operational coordination accordingly.
Here’s how it might be used in a real-world scenario:
- Officer: "Dispatch, 10-40 for lunch break, back in 30 minutes."
- Dispatch: "10-4, unit 12 marked out of service until return."
In this exchange, the officer communicates that they will not be available for active calls. Using 10-40 ensures dispatch knows to redirect assignments to available units while maintaining awareness of unit status.
Operational Purpose
10-40 is critical for managing resources, ensuring coverage, and maintaining operational efficiency. By clearly marking units as temporarily unavailable, dispatch can prevent overloading active units and coordinate response to ongoing incidents effectively.
This code is commonly used during breaks, vehicle maintenance, shift changes, or when a unit must be removed from active duty temporarily. It helps maintain accountability and accurate resource tracking.
Officer Safety And Coordination
Declaring a 10-40 allows dispatch and other units to maintain situational awareness and avoid assigning calls to unavailable units. Officers may report 10-6 (busy) while completing tasks during this period and acknowledge return to service with 10-4 (acknowledgment). Location updates via 10-20 help track units even while out of service.
Variations And Agency Practices
Some agencies apply 10-40 for any temporary unavailability, while others differentiate between short breaks, long-term maintenance, or out-of-service status. Local procedures may define when and how units report 10-40, as well as whether coverage adjustments or backup units are required.
Plain-Language Alternatives
Agencies emphasizing plain-language communication may replace 10-40 with phrases such as:
- "Unit temporarily unavailable."
- "Out of service."
- "Silent / no calls."
Related 10-Codes
Codes commonly associated with 10-40 include 10-4 (acknowledgment), 10-6 (busy), 10-20 (location), 10-23 (arrived on scene/standby), and 10-34 (remove units/radio silence). Together, these codes help maintain clear communication, operational tracking, and safe unit management.