How to Call WCF Services Synchronously and Asynchronously

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using WFCCallExample.Properties;


namespace WFCCallExample
{
    /// <summary>
    /// Interaction logic for MainWnd.xaml
    /// </summary>
    public partial class MainWnd : Window
    {
        public MainWnd()
        {
            InitializeComponent();
            this.Loaded += new RoutedEventHandler(MainWnd_Loaded);
        }

        void MainWnd_Loaded(object sender, RoutedEventArgs e)
        {
            DataContext = Settings.Default;

            ((TabItem)ApplicationMainTab.Items[0]).Content
                = new WCFCallExample(false);

            ((TabItem)ApplicationMainTab.Items[1]).Content
                = new WCFCallExample(true);
        }
    }
}