Have you ever tried to handle authentication for a mobile app, regardless of the platform? Every provider has its own protocol, which forces you to write and maintain a lot of different implementations. Writing protocol code on devices might not always be easy, and the fact that web protocols are moving targets which change every few months doesn't help. Nobody knows this better than Caleb Baker, Senior Program Manager on the ACS team. Caleb has been working on making it real easy to outsource to ACS your mobile authentication woes: his solution is the base of the new ACS+WP7 hands-on lab in the Identity Developer Training Kit. In this quick interview Caleb examines in details the authentication flow of his solution, from the Silverlight control which wraps most of the ACS integration to the way in which the phone app uses OAuth2 to secure calls to one OData service. Caleb also worked on improving the way in which errors are handled in federated scenarios, and drove interesting features in ACS which can really help with that: thanks to his explanation here, you'll be able to use those features in just minutes. Folks, don't miss this interview! If you want to know more about the new ACS, check out the announcements below and the other videos in this IdElement special Stuart Kwan announces the RTW of ACS2.0Justin Smith on the 2. release of ACSAaron Smalser on the ACS portal and the HDR featuresFind out more about ACS: Newest samples and videos about ACSACS CodePlex Site (for code samples) Identity Training KitWindows Azure Platform Security Forum