Why at a military funeral do they have the 3 volley salute?

The 3 volley salute has nothing to do with the 21 gun salute. It started during wartime when both sides would stop fighting long enough to clear their dead. Then, when they were "finished caring for their dead" they would send 3 volleys to signal the other side that they were ready to start fighting again. Can be 3 guns shooting 3 volleys, can be 5 guns shooting 3 volleys, can be 7 guns shooting 3 volleys.