We can set a variable that can be accessed on all pages of a Windows Phone App
Step1:
App.xaml.cs
public partial class App : Application
{
public string sName { get; set; }
}
Step2:
Now access application variable "sName" in entire application like this
(App.Current as App).sName = "Test value";//set value
string myvalue=(App.Current as App).sName;//get value