Hi, 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. The document explans the problems with SIP record route recommendations from prior documents and proposes a solution that should result in consistent behaviour. While I am not intimately familiar with SIP and SIP proxying, I think that this is a good thing. The Security Considerations section is appropriate for this document. I did come across two nits in my review. The first is that the Abstract contains "sip" and "sips" but those are all uppercase throughout the rest of the document. The rest of that paragraph could use some scrutiny as well to make some parts of it more clear. Also, the third paragraph in section 5 talks about a "spiral". That concept is not defined in this document so I couldn't tell if it is a good thing, or a bad thing. Regards, Chris