void MainWindow_OnClosing(object sender, CancelEventArgs e)
        {
            if (SoftPhone != null)
            {
                SoftPhone.CloseCall();
                SoftPhone.CloseAlarmCalls();
            }

            foreach (var camera in ModelList)
            {
                camera.Disconnect();
                camera.Close();
            }

            foreach (var viewer in _videoViewerList.Where(viewer => viewer.Model != null))
            {
                viewer.Model.Disconnect();
                viewer.Model.Close();
            }
        }
 void CallHangUpButton_Click(object sender, RoutedEventArgs e)
 {
     SoftPhone.CloseCall();
 }