private ISession StartConversation(SessionType sessionType, bool enableVideo)
        {
            BugTracer.Get(BugId.N01).Trace(string.Format(@"StartConversation: {0}, {1}", sessionType, enableVideo));

            IPresentity presentity = this.ContactsWindow.GetSelectedContact();

            BugTracer.Get(BugId.N01).Trace(string.Format(@"StartConversation: {0}", presentity.Uri));

            ISession session = this.Endpoint.FindSession(sessionType, presentity.Uri);

            BugTracer.Get(BugId.N01).Trace(string.Format(@"StartConversation: session {0}found", (session == null) ? "not " : ""));

            if (session != null)
            {
                if (enableVideo)
                {
                    (session as IAvSession).EnableVideo();
                }

                this.Endpoint.RestoreSession(session);
            }
            else
            {
                session = this.Endpoint.CreateSession(sessionType);

                if (enableVideo)
                {
                    (session as IAvSession).EnableVideo();
                }

                BugTracer.Get(BugId.N01).EndTrace(@"StartConversation -- endtrace");

                session.AddPartipant(presentity.Uri);
            }

            return(session);
        }