My iPhone rings so does my iPad when I gets call which is normal thing. But recently my iPad got started ringing without any display number or any change in display, it was just sound(I was watching on Youtube on iPad but ipad display did not go away, it was just sound). But same time there was no call on iPhone. How can this possible? What could be wrong. Thanks
It sounds to me like a bug in iOS. If you aren't running the current version of iOS (iOS 9.1), update it by going into Settings > General > Software Update, as updating could fix your issue. If you are running iOS 9.1, report the bug to Apple, and wait for iOS 9.2 and hope that it does the trick.