The phone is not a tiny desktop. We thought porting a desktop Silverlight application to WP7 meant selecting a feature subset and reformatting screens to a smaller footprint. That’s doesn’t work. Some of the data are the same; some business operations are the same. But what the user does on a phone is different. Tasks may take seconds; they cannot take minutes or hours. Input must be minimized. We had to re-design to meet realistic phone user goals and behaviors. This session reports our lessons learned and offers guidelines for an effective phone application design.