Vibrating alert
A vibrating alert is a feature of communications devices to notify the user of an incoming connection. It is particularly common on mobile phones and pagers and usually supplements the ring tone.
Vibrating alerts are primarily used when a user cannot hear the ring tone (a noisy environment or through hearing loss) or wants a more discreet notification. However, when the device is placed on a hard surface, it can often be as loud or louder than a ringtone. Most 21st-century mobile phones are fitted with a vibrating alert.
The vibrating alert is produced by a small electric motor connected to an off-center weight.
Another method for receiving alerts is using a device for receiving a warning signal through heating elements instead of vibrating alert.[1]