Its an Iphone 4 and i have Vibrate on Ring ON, Vibrate on Silent OFF, Ringer and Alerts turned all the way down. Why will it no vibrate when i get a call?
I would try turning "vibrate on silent" to "ON" and see what happens... I guess it could be possible that since you have your volume turned all the way down, the phone assumes you are in "silent" mode? I am really guessing here! LOL!