A call is a great tool to have with you.
I've called deer in with anything from subtle little "blehh"" sounds, to full bore "BLAAAHHHHH!" sounds.

The "bleh" early or late seems to work best.
I think they kinda use it like a bobwhites' little "boip" chirp.
Like a locator to keep tabs on each other. Reasurrance.

The "BLAAAHHHHH!"(think screaming goat) is, If I shoot a deer out of a group near me.
Many times (if not most times), after the initial scatter, several will circle back to see about their missing "bellowing" comrade.
It sounds hokey, but I swear it has worked too many times.
They most likely would check up anyway, but I feel the call speeds up the process.