Apple phones keep in mind all the situations that a user has to face and most important is the situation in which the phone bell is needed to be kept off yet a signal of call. In this situation the vibration mode is compulsory. How embarrassing that would be if your iphone 4 does not switch to vibration mode or keeps on vibrating. If so then consult mycelcare in Dubai at 042 411494 to serve you through the best of their knowledge and skills. We have seen that either the vibration button is out of order or the vibrator. We can provide the solution of both. So avail the service of our pick and drop crew to get the fault fixed.