If dispatch says 10-21, what should you do?

• A. Disregard
• B. Call by telephone
• C. Standby
• D. Send backup

Answer: (B)

In dispatch language, a 10-21 instruction means to call by telephone. When you hear that, the proper action is to contact the dispatcher or the appropriate office by phone to relay your status, report details of the scene, or receive further instructions. This keeps important information flowing directly and avoids clogging the radio channel with every update. It’s not about ignoring the instruction, waiting on radio standby, or automatically sending backup—those actions don’t fulfill the directive to communicate by telephone. If you can’t reach by phone right away, follow your agency’s contact procedures and attempt the call again, documenting your efforts.