Beeper (noun)

1. A device that makes a beeping sound as a signal or warning.
2. A small electronic device that can be carried and that makes a beeping sound to alert the user to an incoming telephone call or message.

Origin:

First recorded in 1965-70; from beep + -er.

Examples:

1. She left her beeper on the table.
2. He set his beeper to vibrate so it wouldn't disturb the meeting.
3. The doctor's beeper went off while he was in surgery.
4. I always keep my beeper with me in case of an emergency.
5. The delivery truck has a beeper to alert the driver when the load needs to be shifted.