private void btnForward_Click(object sender, RoutedEventArgs e)
        {
            if (Model.SelectedCall == null)
            {
                return;
            }

            if (!Model.SelectedCall.IsIncoming || !Model.SelectedCall.CallState.IsRinging())
            {
                return;
            }

            ForwardWindow forwardWin = new ForwardWindow(this);
            bool?         ok         = forwardWin.ShowDialog();

            if (ok != null && ok == true)
            {
                string target = forwardWin.Target;

                // forward call
                Model.ForwardCall(target);
            }
        }
        private void btnForward_Click(object sender, RoutedEventArgs e)
        {
            if (Model.SelectedCall == null)
                return;

            if (!Model.SelectedCall.IsIncoming || !Model.SelectedCall.CallState.IsRinging())
                return;

            ForwardWindow forwardWin = new ForwardWindow(this);
            bool? ok = forwardWin.ShowDialog();
            if (ok != null && ok == true)
            {
                string target = forwardWin.Target;

                // forward call
                Model.ForwardCall(target);
            }
        }