In order for your iPhone to vibrate when it receives calls, texts, and other notifications, Vibrate on Ring and Vibrate on Silent need to be turned on.
How Do I Make Sure Vibrate On Ring & Vibrate On Silent Are On?
- Open the Settings app.
- Tap Sounds & Haptics.
- Turn on the switches next the Vibrate on Ring and Vibrate on Silent. You'll know they are on when the switches are green and positioned to the right.