beeper

Short definition from Wiktionary

Noun

1. 1
   Something that makes a beeping sound: A simple computer speaker.
2. 2
   Something that makes a beeping sound: A pager (wireless telecommunication device).
3. 3
   Something that makes a beeping sound: A robot.
4. 4
   A broadcast interview taking place over the telephone (originally having to include a beeping sound to indicate that it was not a live broadcast).