The navigation system in Windows Phone XAML apps is based on the Silverlight for the browser navigation model. The navigation class model looks a little different in the phone SDK however. Rather than Silverlight
Page controls, Windows Phone apps use the subclasses
PhoneApplicationFrame and the
PhoneApplicationPage (see Figure 3.4).
Page must not be used directly in your app. They are prohibited because of underlying differences in the way the run-time environment interacts ...