I am running into issue and would appreciate expert’s help here. I am trying to get screen resolution so that I can use appropriate layouts/images based on phone types.
As stated in the MSDN article you linked to: MSDN
Windows Phone 7 only supported a single resolution, 800 x 480. Since your project is targeting WP7, that would be the expected behavior. If you are developing a Windows Phone 8 project, then you should see that App.Current.Host.Content.ScaleFactor should return different results.
You will probably need to create a WP8 project to customize for the various resolutions in WP8. If you still want to support WP7 devices, then you will need to create a separate WP7 project.