End of Watch Call

The End of Watch Call or Last Radio Call is a ceremony in which, after a police officer's death (usually in the line of duty but sometimes from illness), the officers from his or her unit or department gather around a police radio, over which the police dispatcher issues one call to the officer, followed by a silence, then a second call, followed by silence, then finally announces that the officer has failed to respond because he or she has died in the line of duty. An example:
Sometimes the dispatcher will mention the officer's honors and may add other words in memoriam.
In some cases the call is made twice, once immediately after the officer's death, then more formally closer to the date of or actually at the officer's funeral. 
History.
The practice of the end of watch call began in the mid–2000s in police departments on the East Coast of the United States. By 2010 the practice had spread to the West Coast, and to firefighters, forest rangers, and game wardens in the United States and Canada.