Summary: I have been asked to review this draft on behalf of the OPS directorate. I think this document is READY with Nits.

I have a few comments for the authors to consider.

Abstract, it says "...when RFC 3455 was updated and obsoleted by RFC 7315". To my understanding, an RFC couldn't be *updated* and *obsoleted* by another RFC at the same time, so suggest s/updated and obsoleted by RFC 7315/obsoleted by RFC 7315. These words appear in three places of this draft. I noticed that these words were already there within RFC 7976, however I believe it can be improved in the Bis draft.

Section 2.2, the last sentence, suggest s/Add statement that P-Visited-Network-ID/Add a statement that the P-Visited-Network-ID, s/non 100/non-100.

Section 3, to make alignment, suggest s/non-100 response message except ACK/non-100 responses, except in ACK. Also s/ACK methods triggered by/ACK requests triggered by and s/in all SIP methods/in all SIP requests.