I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. I was asked to review this document because I'd reviewed draft-drage-sipping-service-identification some time ago. Only, this document doesn't derive from that one, but, rather, from draft-rosenberg-sipping-service-identification, and it has none of the issues I had with the other document. I find this one useful and enlightening, and a good contribution to the informational stream about SIP. No issues, from a secdir point of view or otherwise. -- Barry Leiba