4 Bible Verses about Trumpets For Signalling

I was in spirit on the Lord's day, and I heard behind me a great voice like that of a trumpet,

After these things I saw, and behold, a door was opened in heaven; and the first voice which I heard, like the voice of a trumpet speaking with me, said: Come up hither, and I will show you things that must be hereafter.

When, therefore, you do a charitable deed, do not cause a trumpet to be sounded before you, as the hypocrites do, in the synagogues and in the streets, that they may be glorified by men. Verily, I say to you, They have their reward.

and to the sound of a trumpet, and to the utterance of words, the hearing of which utterance caused the people to entreat that the word might not be spoken to them again;