I want to make Audio Call  to X  and get result : success/fail ( + reason )

I want to make Video call to X and get result : success/fail ( + reason)

(later Sharing test )

I don't find any event to connect. Conversation / Groups / Self events doesn't fit well....

I need somehow to get the Call object from the conversation ,and connect to StateChanged event ,

but I cant get it.

Any ideas? 

How the Lync Client receive message  success/fail when trying to make A/V calls , like no camera / no audio device / etc'

For example , audio test  :

var participants = new List<string>();

                participants.Add(sip);

                _automation.BeginStartConversation(
                    AutomationModalities.Audio,
                    participants,
                    null,
                    StartConversationCallback,
                    _automation);

Thanks