Related Clues:

• Noisemaker noise
• Restaurateur Shor
• A message may be left after it
• Horn output
• Car sound
• Answering-machine feature
• Trumpets and tubas
• Jam chorus
• Electronic reminder
• Horn note
• Beepers
• Sound from a jam
• Toots the horn
• Play on pipes, palindromically
• Drivers may hit them on purpose