First call

At a U.S. military installation it is a pre-reveille "courtesy" signal, sounded around 05:50, originally to assemble the trumpeters to deliver the reveille that would be forthcoming at 06:00.

[1] At a horse race, "First call" is a signal that all mounts should be at the paddock exit in order to proceed to the track to begin the post parade.

[2] The tune is usually sounded by a bugler five to ten minutes before the scheduled start time of the race.

In Japan, a "fanfare" is played or performed just before the actual race starts, rather than five to ten minutes before, in order to proceed to the gates.

[6] And, "First call" is also used as a fanfare at Funabashi Racecourse, a regional horse race track in Japan.