bool registerResult = WebRequest.RegisterPrefix("https://", WebRequestCreator.ClientHttp);

Service1Client clientServer = new Service1Client();
clientServer.Endpoint.Address = new EndpointAddress(new Uri("http://localhost:7070/hello", UriKind.RelativeOrAbsolute));
clientServer.GetServerData += OnGetServerDataCompleted;
clientServer.GetServerDataAsync();
 
private void OnGetServerDataCompleted(object sender, GetServerDataCompletedEventArgs e)
{
 if (!e.Cancelled)
 {
  if (e.Error != null)
  {
   if (e.Error is CommunicationException
     || e.Error is TimeoutException
     || e.Error is EndpointNotFoundException)
   {
    MessageBox.Show("Network error");
    return;
   }
    MessageBox.Show("Other error")
  }
  else {
    MessageBox.Show("No error")
  }
 }
}