.net - How to detect file transfer in Lync conversation -

i trying log lync convrsation using console application uses lync sdk access lync client. code looks similar this:

       public void getnotifiedaboutmessagesent()     {         var client = lyncclient.getclient();          foreach (var conversation in client.conversationmanager.conversations)             foreach (var participant in conversation.participants)                 ((instantmessagemodality)participant.modalities[modalitytypes.instantmessage]).instantmessagereceived += participant_instantmessagereceived;     }      //event handlers     void participant_instantmessagereceived(object sender, messagesenteventargs e)     {         logtext("message received");     } 

participant_instantmessagereceived event raised when message sent or received not raised when file sent (or received). there event similar on file transfer can subscribe or way notification when file sent on lync?