Current voip calls on iOS are very unuser friendly. *When an incoming call comes in for say Google Hangouts it shows a banner with a number and no name. *If the call comes in while the screen is locked then you have to unlock the screen first to get to the call. *Usually by this time you are likely to have missed the call. *Third party calls should work like the iPhone dialer, it should take up the whole screen with access to contacts for caller ID. *It should also give you the option to accept or reject the call in addition to being able to answer the call without entering the passcode lock. *Here are two pictures of the difference between the way iOS handles a hangout call vs how android handles it: iOS - https://www.dropbox.com/s/zvynnubwe3a3dgu/iOS Hangout Call.png?dl=0, Android -*https://www.dropbox.com/s/85dewkoo5340wcr/Android Hangouts Call.png?dl=0.