http://blogs.msdn.com/b/nima_kamoosi/archive/2013/01/05/walkthrough-of-using-callcontext-with-system-services.aspxCallers of a Custom X++ Service can specify CallContext as part of the operation signature on the generated service reference proxy. See http://technet.microsoft.com/en-us/library/hh582244.aspx . However the operation signatures for AX System servicesen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)