SUCCINCT on CALLKIT
Introducing CallKit in iOS, and how to implement it in VOIP apps is causing buzz. ZORO.IM for business has promulgated and implemented the exemplary CallKit.
Before, the user experience with 3rd party VoIP app in iOS was cumbersome. If the phone is locked and user is receiving an incoming a call, it will be received as notification. Since the notifications are temporary it can be easily missed.