Hi, I have a WCF service and without changing any code on the client side, is there a way that I can know the detail information of the caller, such as the MachineName, and ApplicationName? Basically, I cannot change the client code to pass those pieces of information over. I tried to use System.Web.HttpContext on the server side to track this information, but HttpContext.Current is NULL. I guess that is not the proper usage of it. Any suggestion? Thanks Sarah