Windows Phone 7 developers realize that having a robust, secure system is just as important for WP7 apps as it is with desktop apps. By using the Forefront Unified Access Gateway as the middle man, Windows Phone 7 users can securely access content on a SharePoint farm.
The Unified Access Gateway (UAG) is a secure access gateway and packet inspector from Microsoft which is designed with the prime goal of protecting enterprise servers from inbound requests. The lack of outbound packet filtering, however, still presents a problem for developers.