private void RegisterCallEventNotification()
{
_callEventCb = (CallEvent callEvent, IntPtr eventData, IntPtr userData) =>
{
_callEvent?.Invoke(null, new CallEventEventArgs(callEvent, CmUtility.GetCallEventData(callEvent, eventData)));
};
int ret = Interop.CallManager.SetCallEventCb(_handle, _callEventCb, IntPtr.Zero);
if (ret != (int)CmError.None)
{
Log.Error(CmUtility.LogTag, "Failed to set call event notification callback, Error: " + (CmError)ret);
CmUtility.ThrowCmException(ret, _handle);
}
}