How to Set Your iPhone on Vibrate for Calls & Texts Know Who is Calling Even if iPhone is Silent with Custom Vibration Alerts Quiet or Vibrate Cell Phone Sign Save 10% Instantly This tiny component inside your phone is responsible for every silent alert you feel. Its called a vibration motor, and when it spins or oscillates at high speed, it creates controlled vibrations My iPhone Doesn't Vibrate! Here's The Real Fix.