Indicating Fax over IP Capability in the Session Initiation Protocol (SIP)
draft-hanes-dispatch-fax-capability-08

[Ballot discuss]
This is a minor Discuss point that I hope we can resolve simply.

Contrary to Pete's Discuss, I believe there *is* protocol to be
discussed in this document, but that it is slightly unclear.

In Section 4
  If a calling UA wants to ensure that a call is routed to a fax
  capable UA, then the UA MUST include the "sip.fax" media feature tag
  in the Contact header field of an INVITE request.

This says, I think, that if a called UA has not registered as fax
capable regardless of whether it is or not, the call will not be routed
to it if the calling UA inludes sip.fax in the INVITE. Thus, the call
will fail and must be retried without sip.fax.

An alternative would be to say:
  If a calling UA wants to ensure that a call is routed to a fax
  capable UA when one exists, then the UA MUST include the "sip.fax"
  media feature tag in the Contact header field of an INVITE request.

This allows the call to be preferentially routed to a UA that has
registred its fax capabilities, but also allows the call to be routed
to some UA if no fax capabilities have been registered.

Whichever was the intention of the authors, I believe it needs to be
more clearly stated.

[Ballot comment]
In Section 1
  To ensure that fax calls are routed to fax capable SIP user agents,
Is that s/are/can be/ ?
The answer probably depends on the resolution of my Discuss.

---

Section 3

"However, fax is somewhat unique..."

Hmmm. "Unique" is binary.

[Ballot comment]
This is a fine document, doing a fine thing, and I think it should go forward... but as an Informational document.  In other words, I support Pete's DISCUSS (but note that it shouldn't hold anything up: an RFC Editor note can take care of this easily).

[Ballot discuss]
This is for the shepherd and the IESG; the authors need not worry about this comment.

This document is simply a media feature tag registration. The only "protocol" here is a few statements in section 4 that say things that amount to "if you want to use sip.fax parameter, you MUST use the sip.fax parameter", which is kind of silly. And I can't imagine that implementation experience would cause this "protocol" to change. So, I see no reason that this document should be other than Informational with the "protocol" MUSTs removed. (I believe the PROTO writeup is incorrect: The registry does not require a standards track document; it only requires "IETF Consensus", which could be an Informational document.)

I will not stand in the way of this document if the rest of the IESG thinks that standards track is appropriate. But I did want to have the discussion.

[Ballot comment]
A procedural remark:
The write-up says "Individual/AD sponsored was the consensus of the DISPATCH WG for this document and the AD(s) agreed to progress the document.  There was no controversy around this decision.  ".

However, for completeness, it would be nice to reference the particular email where this consensus was documented.

IANA has reviewed draft-hanes-dispatch-fax-capability-06 and has the following comments:

IANA understands that, upon approval of this document, there is a single action which IANA must complete.

In the iso.org.dod.internet.features.sip-tree (1.3.6.1.8.4) subregisty of the Media Feature Tags - iso.org.dod.internet.features (1.3.6.1.8) registry located at:

http://www.iana.org/assignments/media-feature-tags/media-feature-tags.xml

a new entry in the subregistry will be added as follows:

Decimal: [ tbd ]
Name: sip.fax
Description: This feature tag indicates whether a communications device supports the ITU-T T.38 [T38] fax protocol ("t38") or the passthrough method of fax transmission using the ITU-T G.711 [G711] audio codec ("passthrough").
Reference: [ RFC-to-be ]

IANA understands that this is the only action required upon approval of this document.

Note: The actions requested in this document will not be completed
until the document has been approved for publication as an RFC.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
Reply-To: ietf@ietf.org
Subject: Last Call:  (Indicating Fax over IP Capability in the Session Initiation Protocol (SIP)) to Proposed Standard


The IESG has received a request from an individual submitter to consider
the following document:
- 'Indicating Fax over IP Capability in the Session Initiation Protocol
  (SIP)'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2012-12-27. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document defines and registers with IANA the new 'fax' media
  feature tag for use with SIP.  Currently, fax calls are
  indistinguishable from voice at call initiation.  Consequently, fax
  calls can be routed to SIP user agents that are not fax capable.  A
  'fax' media feature tag implemented in conjunction with caller
  preferences allows for more accurate fax call routing.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-hanes-dispatch-fax-capability/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-hanes-dispatch-fax-capability/ballot/


No IPR declarations have been submitted directly on this I-D.

PROTO questionnaire for: draft-hanes-dispatch-fax-capability-06.txt

To be Published as: Proposed Standard

Prepared by: Mary Barnes (mary.barnes@polycom.com) on 27 November 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?

This document is requested to be published as a Proposed Standards. This the proper type of RFC as it requires IANA registrations for a registry that requires a standards track RFC.  This RFC type is indicated on the title page.

    (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:

This document defines and registers with IANA the new 'fax' media
feature tag for use with SIP.  Currently, fax calls are
indistinguishable from voice at call initiation.  Consequently, fax
calls can be routed to SIP user agents that are not fax capable.  A
'fax' media feature tag implemented in conjunction with caller
preferences allows for more accurate fax call routing.
 
        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
        document?
 
Per the RAI area process for new work, this document has been reviewed in the DISPATCH WG. The DISPATCH WG does not progress any documents as WG documents.  The DISPATCH WG selects one the following actions for contributions to the WG that have been adequately reviewed and discussed:
- None in the case of work items for which there is inadequate interest or feedback indicates that the work should not be progressed (e.g., it's a bad idea or not within scope for RAI area or IETF)
- New work item in currently chartered WG
- New WG or mini-WG in the case where the deliverable is likely a single document - e.g. a new SIP header
- IETF official BoF - typically for work items that are of broad interest and potential impact within the RAI area and across areas.
- Individual/AD sponsored - for items limited in scope and applicability

Individual/AD sponsored was the consensus of the DISPATCH WG for this document and the AD(s) agreed to progress the document.  There was no controversy around this decision. 

        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 document is a dependency for the SIP Forum Fax over IP (FoIP) Task group.  While the use of fax is not widespread, there are key areas where it is still required (e.g., medical field).  There are vendors that are planning to implement this specification. 

        Personnel
        Who is the Document Shepherd? Who is the Responsible Area
        Director?

Mary Barnes (DISPATCH WG co-chair) is the Document Shepherd.  Gonzalo
Camarillo is the Responsible AD.

    (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.

The Document Shepherd has thoroughly reviewed this version of the document.  A previous version had been reviewed, however, issues were discovered that have since been fixed.  Thus, the document is deemed ready for publication.
     
    (4) Does the document Shepherd have any concerns about the depth
        or breadth of the reviews that have been performed?

There are no concerns about the depth or breadth of the reviews.


    (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.
No.

    (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.

There are no specific concerns or issues.

    (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.

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

No,

    (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?

There is WG consensus that AD sponsored is the best approach for progressing this document. No one has expressed concerns about its progression. 

    (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.)

No.

    (11) Identify any ID nits the Document Shepherd has found in this
        document. (See http://www.ietf.org/tools/idnits/ and the
        Internet-Drafts Checklist). Boilerplate checks are not enough;
        this check needs to be thorough.

The two comments and one warning produced by IDnits version 2.12.14 are not issues.

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

No formal reviews other than review in the DISPATCH WG are required for this document.  At least 6 WG participants including Dan Wing,
Paul Kyzivat, Christer Holmberg, Charles Eckel, and Dale Worley
have reviewed previous versions of the document.

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

Yes.

    (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?

No.

    (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.

No.

    (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.

No.

    (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).

This document adds a new media feature tag to the SIP Media Feature Tag
Registration Tree as required by RFC 3840.  The document shepherd has reviewed the IANA considerations section and has confirmed that the registration is correct for this media feature tag.  No new IANA registries are defined in this document.

    (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 defines no 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.

No reviews or automated checks were required as this document does not use any formal language requiring such.