private void Reject_Click(object sender, RoutedEventArgs e)
 {
     voiceChat.Cancel();
     Dispatcher.Invoke(() =>
     {
         ShowCancelled();
     });
 }
 private void StopVoiceChat_Click(object sender, RoutedEventArgs e)
 {
     if (voiceChatContext != null)
     {
         voiceChatContext.Cancel();
     }
 }