title: What is InCallService(Android) equivalent in iOS
body: <p>In Android, they have this new API called InCallService where you can get call events and for each call object you can do some action. I'm looking for equivalent in iOS. In iOS, I wanted to do the achieve the same thing specifically for outgoing call also. In iOS there is CXCallObserverDelegate protocol but in this case I can only get UUID of the call that's all I can get. I'm not able to do any additional action for the call. I wanted to execute DTMF tone once the call is active but it is not possible. In CallKit there is cxaction called CXPlayDTMFCallAction but this only applies for VOIP application and what I need is to execute the dtmf for gsm calls. Does anybody have any solution for here?</p>