Some of the buttons on iphone 4 are related to one another in their function. Headphone jack is used to connect head or ear phones for personally listening. The volume buttons are used to loud up or slient down the voice. The mute button is used to transfer the smart phone to vibration mode. The head phone jack may be not working to connect the head phones. The volume button may be unable to change the volume level. The iPhone 4 may not be muting due to button problem or faulty vibrator. For these faults consult us on 04 42 11494 for needed repair or replacement at our service centre in DUBAI.