"This document defines new mechanisms for the Session Initiation Protocol (SIP) in support of privacy. Specifically@ guidelines are provided for the creation of messages that do not divulge personal identity information. A new ""privacy service"" logical role for intermediaries is defined to answer some privacy requirements that user agents cannot satisfy themselves. Finally@ means are presented by which a user can request particular functions from a privacy service."
RFC 3323-2002 history
2002RFC 3323-2002 A Privacy Mechanism for the Session Initiation Protocol (SIP)