Ontario Security Guard License Practice Test

The code 10-9 is a universally recognized radio ten code used in two-way voice radio communication, especially among police and other emergency service personnel. It is used when the receiver didn't understand the last transmission due to factors like radio static, background noise, or simply missed hearing the message. The code signifies 'Repeat' or 'Say again', meaning the speaker needs the dispatcher to repeat the last message. Hence, 10-9 is the radio code for asking someone to repeat their last transmission.