private void btnAddPhoneLine_Click(object sender, RoutedEventArgs e)
        {
            AccountModel model = new AccountModel();
            AccountWindow accountWin = new AccountWindow(this, model);
            bool? ok = accountWin.ShowDialog();

            if (ok != null && ok == true)
            {
                var line = Model.AddPhoneLine(model.SIPAccount, model.TransportType, model.NatConfig, model.SRTPMode);

                if (Model.SelectedLine == null)
                    Model.SelectedLine = line;
            }
        }