When you have set / activate the call waiting, you need to be told about the incoming calls while you are busy on the call. You may set the vibrate to inform you about the incoming call while you are on call. This is a very simple function.
You may set / activate the function by following the instructions:
1: Tap the ‘Phone Dialer’, available on the Home screen of your Android KitKat 4.4.3 smartphone to open up the phone dialer screen.2: Tap the ‘Settings’ button, available on the right bottom corner of the ‘Phone Dialer’ screen. It will open up a settings popup menu.
3: In the ‘Settings’ popup menu, tap the ‘Call settings’. 4: On the ‘Call settings’ screen, see ‘Vibrate on call waiting’ under the IN-CALL VIBRATIONS. It is unchecked, i.e. disabled. 5: Tap to check the ‘Vibrate on call waiting, under the IN-CALL VIBRATIONS and enable it.