I am the requested ARTART reviewer for this document.

My primary knowledge of SIP comes from hoping and waiting for STIR/SHAKEN to be adopted. It really needs SIP experts to do a close review.

I read the document.  It is like a conformance document, full of normative language about which RFC's MUST be implemented, and which parameters in them SHOULD have specific values.  I cannot comment on whether the sum total of all requirements makes sense or not.

The document is well-written. The problem space is well-described. Each individual obligation (MUST MAY SHOULD etc) is in enough detail to make it understandable.