"Vibration alerts" refer to signals or notifications received through a vibrating sensation, typically on electronic devices or wearable technology, instead of relying on sound or visual cues. Full definition
It also offers vibration alerts for events such as being inactive for too long. (9to5google.com)
This phone is basically for people who work in noisy environments and often miss calls and can not afford high end phones that come with vibration alert. (gogi.in)
Did you know that you can set custom vibration alerts for each of your contacts? (cultofmac.com)