Shepherd writeup

As required by RFC 4858, this is the current template for the Document 
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Informational, which is noted on the title page header. 

This draft specifies a SIP "P-" header field, P-Charge-Info. The "P-" prefix to a SIP header field name indicates that the header field is preliminary, private, or proprietary and is considered Informational. 

"P-" header fields were originally allowed by the first version of the Change Process for the Session Initiation Protocol (RFC 3427). However, the updated version of the Change Process (RFC 5727, obsoleting RFC 3427) deprecates "P-" header fields, but provides a path for grandfathering those that existed before RFC 5727 was published in 2010. The P-Charge-Info header field has been in use in various SIP networks since around 2007 and was captured originally in draft-york-sipping-p-charge-info in 2008. 

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

 Technical Summary

  Relevant content can frequently be found in the abstract 
  and/or introduction of the document. If not, this may be 
  an indication that there are deficiencies in the abstract 
  or introduction.

The P-Charge-Info header field is a SIP header field that carries the identity/number used by the network for billing purposes. This information is separate from the Caller ID, which is carried in the P-Asserted-Identity or From header fields. Certain network configurations have found it useful to carry the billing identity separately, especially when it differs from the identify of the caller, for instance, when keeping track of billing information for an enterprise rather than the enterprise's various phone numbers. 

 Working Group Summary

  Was the document considered in any WG, and if so, why was
  it not adopted as a work item there? Was there controversy
  about particular points that caused the WG to not adopt the

This draft was originally discussed back in 2008 in the SIPPING working group and received a lot of feedback from participants, but was not adopted. At the time, the SIP change process (originally documented in RFC 3427) was being updated and the working group was shutting down (mailing list closed in 2011). There were no calls for adoption or for consensus on the SIPPING mailing list. This document shepherd's read of the archives is that participants were for the most part neutral about this draft, but willing to provide feedback. In general, SIPPING participants frowned upon new P- header fields, and that was reflected in the updated SIP change process (RFC 5727). 

This draft was also discussed briefly in the DISPATCH working group, but was not dispatched. A former RAI AD suggested that the authors should pursue AD-sponsorship of the draft. 

 Document Quality

  Are there existing implementations of the protocol? Have a 
  significant number of vendors indicated their plan to 
  implement the specification? Are there any reviewers that 
  merit special mention as having done a thorough review, 
  e.g., one that resulted in important changes or a 
  conclusion that the document had no substantive issues? If 
  there was a MIB Doctor, Media Type or other expert review, 
  what was its course (briefly)? In the case of a Media Type 
  review, on what date was the request posted?

This header field has been deployed in multiple networks since 2007. 

The Acknowledgements section of this document thanks the multiple people who have provided feedback over the years on this draft.

As per the SIP change process (RFC 5727), this draft was reviewed by the Designated Expert for SIP Header Fields, Adam Roach, in February 2018. His feedback was incorporated in the -03 version. 


  Who is the Document Shepherd? Who is the Responsible Area

Document Shepherd: Jean Mahoney

Responsible Area Director: Ben Campbell

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

Since this document predates the Document Shepherd, the Document Shepherd went through the mail archives to ensure that feedback was addressed. She considers the draft ready to proceed. 

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed? 


(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.


(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the interested community has
discussed those issues and has indicated that it still wishes to advance
the document, detail those concerns here.

No concerns. 

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Each author has confirmed conformance with BCPs 78 and 79.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any discussion and conclusion regarding the IPR

No disclosure has been filed.

(9) How solid is the consensus of the interested community behind this
document? Does it represent the strong concurrence of a few individuals,
with others being silent, or does the interested community as a whole
understand and agree with it? 

When it was originally discussed in the SIPPING working group, participants were neutral to non-supportive (but did not actively dismiss) of the idea of registering a P- header field since P- header fields were being deprecated at the time. SIPPING working group participants suggested that the authors consider some alternative header fields before specifying this header field. The reasons why these alternatives don't work are covered in Section 5.

The authors have stated that the community that uses the P-Charge-Info header field wants the header field registered so that its specification can be found and the creation of other P-headers can be avoided. 

(10) Has anyone threatened an appeal or otherwise indicated extreme 
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.) 


(11) Identify any ID nits the Document Shepherd has found in this
document. (See and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be

The Document Shepherd brought up any ID nits found to the authors, who incorporated the feedback. idnits finds no issues with version -07 of the draft. 

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

As per the Change Process for the Session Initiation Protocol (SIP) (RFC 5737), this draft received an Expert Review from Adam Roach. 

(13) Have all references within this document been identified as
either normative or informative?


(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure. 


(16) Will publication of this document change the status of any existing
RFCs? Are those RFCs listed on the title page header, listed in the
abstract, and discussed in the introduction? If the RFCs are not listed
in the Abstract and Introduction, explain why, and point to the part of
the document where the relationship of this document to the other RFCs
is discussed. If this information is not in the document, explain why
the interested community considers it unnecessary.


(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The Document Shepherd provided guidance on writing the IANA considerations section to make it clear which SIP sub-registry was being updated. 

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

This document does not create any new IANA registries. 

(19) Describe reviews and automated checks performed by to validate
sections of the document written in a formal language, such as XML code,
BNF rules, MIB definitions, etc.

The ABNF received thorough review from SIPPING working group participants and the Designated Expert for SIP header fields.