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Versions: 00 01 02

STIR                                                           M. Barnes
Internet-Draft                                                 iconectiv
Intended status: Informational                          October 22, 2018
Expires: April 25, 2019


   Session Initiation Protocol (SIP) Call Flow Examples with PASSporT
                       Diversion and History-Info
             draft-barnes-stir-passport-div-hi-callflows-02

Abstract

   This document focuses on use cases and call flows which include the
   History-Info header field and a SIP Identity header field with a
   PASSport with a "div" claim in cases of retargeting.  These use cases
   are derived from those provided in the SIP History-Info call flows
   document.  The objective is to describe the optimal way to correlate
   the History-Info header fields with a PASSporT with diversion
   information to increase the level of confidence in the History-Info
   header field by the terminating entity making use of the information.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 25, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   2
   3.  Detailed call flows . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  PBX Voicemail Example . . . . . . . . . . . . . . . . . .   3
     3.2.  Consumer Voicemail Example  . . . . . . . . . . . . . . .  10
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
     5.1.  Acknowledgements  . . . . . . . . . . . . . . . . . . . .  16
   6.  Informative References  . . . . . . . . . . . . . . . . . . .  16
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Overview

   Many services that use SIP require the ability to determine why and
   how the call arrived at a specific application.  The use cases
   provided in [RFC7131] illustrate the use of the History-Info header
   field [RFC7044] for example applications and common scenarios.  The
   document [I-D.ietf-stir-passport-divert] extends the PASSporT,
   defined in [RFC8225] to cryptographically-sign the calling party
   information, to include an indication that a call has been diverted
   from its original destination to a new one.  This document discusses
   the applicability and use of this PASSporT extension for diverted
   calls in the context of scenarios for which use of the History-Info
   header field is essential for processing by the terminating entity.
   Descriptions of the example use cases, call flow diagrams and
   messaging details including both History-Info header field and a SIP
   Identity header field with a PASSport capturing the retargeted
   identity are provided.

2.  Conventions and Terminology

   The term "retarget" is used as defined in [RFC7044].  The term
   "divert" refers to a specific type of retargeting and is used per the
   context in [I-D.ietf-stir-passport-divert].  The terms "location
   service", "redirect" and "address-of-record (AOR)" are used
   consistent with the terminology in [RFC3261].








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3.  Detailed call flows

   The scenarios in this section provide sample use cases for the
   History-Info header along with a PASSporT(s) containing the
   retargeted identity for informational purposes only.  They are not
   intended to be normative.  In many cases, only the relevant messaging
   details are included in the body of the call flow.

   The current objective of these call flows is for discussion purposes
   to determine if the current set of information proposed to be
   captured in the PASSporT in cases of retargeting is sufficient.  It
   is anticipated that the cases where a "div" PASSporT is added would
   be cases where the a History-Info header field has been added and
   tagged "mp", indicating the hi-targeted-to-URI represents a user
   other than the target user associated with the Request-URI in the
   incoming request that was retargeted.

   Given that the History-Info header field captures a full set of
   information as to why a request is retargeted, it might seem
   reasonable to just add the PASSporT to the History-Info header field
   as opposed to adding a new Identity header field in cases of
   retargeting.  However, in that case, that would then require the
   terminating user to search the History-Info entries to determine if
   the request was "diverted" and whether the identity at the point of
   retargeting was authenticated.  An alternative is that rather than
   just adding the retargeted destination, the complete History-Info
   header field could be added to the PASSporT.  This could increase the
   confidence at the terminating user that all the information is valid.
   At a minimum the "index" should be included as it's possible to have
   entries containing the same target.  For example, a proxy forwards a
   request in the case of loose routing and then the request is
   retargeted at the next hop.  Also, there are cases whereby the first
   entry with a specific tag is most relevant.  Thus, being able to at
   least correlate the contents of that entry with a PASSporT with
   diverted information could be quite useful.

   Editor's note: currently, there are only two examples - consumer and
   PBX voicemail.  It's probably quite useful to document more of the
   flows once there is agreement on the best approach for correlating
   the information.

3.1.  PBX Voicemail Example

   A typical use case for voicemail is one whereby the original called
   party is not reachable and the call arrives at a voicemail system.
   In some cases multiple alternate destinations may be tried without
   success.  The voicemail system typically requires the original called
   party information to determine the appropriate mailbox so an



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   appropriate greeting can be provided and the appropriate party
   notified of the message.

   In this example, Alice calls Bob, whose SIP client is forwarded to
   Carol.  Carol does not answer the call, thus it is forwarded to a VM
   (voicemail) server (VMS).  In order to determine the appropriate
   mailbox to use for this call, the VMS needs the original target for
   the request.  The original target is determined by finding the first
   hi-entry tagged with "rc" or "mp" and using the hi-entry referenced
   by the index of "rc" or "mp" header field parameter as the target for
   determining the appropriate mailbox.  This first hi-entry is used to
   populate the "target" URI parameter as defined in [RFC4458].

   If the SIP Identity header field with "div" claims has been added by
   the entities retargeting, it can be ascertained that the call should
   be forwarded to Bob's voicemail prior to forwarding the call to
   voicemail.  The value of the "tn" in the "div" field of the claim
   should match the hi-targeted-to URI in the hi-entry with the hi-index
   matching the "hi" value in the "div" claim.

   The reason associated with the first hi-entry tagged with "rc" or
   "mp" (i.e., 302) could be used to provide a customized voicemail
   greeting and is used to populate the "cause" URI parameter as defined
   in [RFC4458].  Note that some VMSs may also (or instead) use the
   information available in the History-Info headers for custom handling
   of the VM based on how and why the call arrived at the VMS.

   Furthermore it is the proxy forwarding the call to VMS that
   determines the target of the voicemail, it is the proxy that sets the
   target of voicemail which is also the entity that utilizes [RFC7044]
   to find the target which is usually based on local policy installed
   by the user or an administrator.

   Alice      example.com       Bob          Carol        VM
   12155551211              12155551212    12155551213

   | INVITE F1    |              |             |          |
   |------------->|              |             |          |
   |              | INVITE  F2   |             |          |
   |              |------------->|             |          |
   |              |              |             |          |
   |  100 Trying  |              |             |          |
   |<-------------| 302 Moved Temporarily F3   |          |
   |              |<-------------|             |          |
   |              |              |             |          |
   |              |      ACK     |             |          |
   |              |------------->|             |          |
   |              |              |             |          |



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   |              | INVITE F4    |             |          |
   |              |--------------------------->|          |
   |              |              |             |          |
   |              |         180 Ringing  F5    |          |
   |              |<---------------------------|          |
   |              |              |             |          |
   | 180 Ringing  |              |             |          |
   |<-------------|              |             |          |
   |              |              |             |          |
   |              |       (timeout)            |          |
   |              |              |             |          |
   |              | INVITE  F6   |             |          |
   |              |-------------------------------------->|
   |              |              |             |          |
   |              |               200 OK  F7              |
   |              |<--------------------------------------|
   |   200 OK     |              |             |          |
   |<-------------|              |             |          |
   |              |              |             |          |
   |                         ACK                          |
   |----------------------------------------------------->|



   F1 INVITE Alice -> Example.com

   INVITE sip:bob@example.com SIP/2.0
   Via: SIP/2.0/TCP  192.0.2.3:5060;branch=z9hG4bK42t2
   Max-Forward: 70
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   Contact: Alice <sip:12155551211@example.com;user=phone>
   Content-Length: <appropriate value>

   [SDP Not Shown]


   F2 INVITE Example.com -> Bob

   INVITE sip:12155551212@example.com;user=phone SIP/2.0
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK12s4
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   Max-Forward: 69
   From: Alice <sip:alice@example.com>;tag=kkaz-



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   To: Bob <sip:bob@example.com>;tag=1928301774>
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   History-Info: <sip:12155551212@example.com;user=phone>;\
                 index=1.1;rc=1
   Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
      joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
      kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
      I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
      q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
      ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
      /biloxi.cert>;alg=ES256
   Contact: Alice <sip:12155551211@example.com;user=phone>
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]

   F3 302 Moved Temporarily Bob -> Example.com

   SIP/2.0 302 Moved Temporarily
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK12s4;\
                                    received=192.0.2.101
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>;tag=2g22d-lnf
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   History-Info: <sip:12155551212@example.com;user=phone>;\
                 index=1.1;rc=1
   Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
      joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
      kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
      I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
      q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
      ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
      /biloxi.cert>;alg=ES256
   Contact: <sip:carol@example.com>;mp=1
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]





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   F4 INVITE Example.com -> Carol

   INVITE sip:12155551213@example.com;user=phone SIP/2.0
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK4522
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   Max-Forward: 69
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   History-Info: <sip:12155551212@example.com;user=phone?\
                      Reason=SIP%3Bcause%3D302>;\
                      index=1.1;rc=1
   History-Info: <sip:carol@example.com;cause=480>;index=1.2;mp=1
   History-Info: <sip:12155551213@example.com;user=phone;cause=480>;\
                      index=1.2.1;rc=1.2
   Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
      joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
      kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
      I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
      q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
      ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
      /biloxi.cert>;alg=ES256
   Identity:..sv5CTo05KqpSmtHt3dcEiO/1CWTSZtnG3iV+1nmurLXV/HmtyNS7L
    eU7d7OV8HweTTDobV3itTmgPwCFjaEmMyEI3d7SyN21yNDo2ER/Ovgtw0Lu5csIp
    pPqOg1uXndzHbG7mR6Rl9BnUhHufVRbp51Mn3w0gfUs=; \
    info=<https://atlanta.example.com/atlanta.cert>;alg=ES256;
    ppt=div
   Contact: Alice <sip:12155551211@example.com;user=phone>
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]

   F5 180 Ringing Carol -> Example.com

   SIP/2.0 180 Ringing
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK4522;\
                                    received=192.0.2.101
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>;tag=setss3x
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1



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   History-Info: <sip:12155551212@example.com;user=phone?\
                      Reason=SIP%3Bcause%3D302>;\
                      index=1.1;rc=1
   History-Info: <sip:carol@example.com;cause=480>;index=1.2;mp=1
   History-Info: <sip:12155551213@example.com;user=phone;\
                      cause=480>;index=1.2.1;rc=1.2
   Contact: Carol <sip:12155551213@example.com;user=phone>
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]

   F6 INVITE Example.com -> VM

   INVITE sip:vm@192.0.2.6;target=sip:bob%40example.com;cause=480\
                                            SIP/2.0
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK4523
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   Max-Forward: 69
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   History-Info: <sip:sip:12155551212@example.com;user=phone?\
                       Reason=SIP%3Bcause%3D302>;\
                       index=1.1;rc=1
   History-Info: <sip:carol@example.com;cause=480?\
                 Reason=SIP%3Bcause%3D408>;\
                 index=1.2;mp=1
   History-Info: <sip:12155551213@example.com;user=phone;cause=480?\
                      Reason=SIP%3Bcause%3D408408>;\
                      index=1.2.1;rc=1.2
   History-Info: <sip:vm@example.com;\
                       target=sip:bob%40example.com;cause=480>;\
                       index=1.3;mp=1
   History-Info: <sip:vm@192.0.2.6;\
                       target=sip:bob%40example.com;cause=480>;\
                       index=1.3.1;rc=1.3
   Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
    joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
    kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
    I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
    q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
    ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
    /biloxi.cert>;alg=ES256
   Identity: ..sv5CTo05KqpSmtHt3dcEiO/1CWTSZtnG3iV+1nmurLXV/HmtyNS7L



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    eU7d7OV8HweTTDobV3itTmgPwCFjaEmMyEI3d7SyN21yNDo2ER/Ovgtw0Lu5csIp
    pPqOg1uXndzHbG7mR6Rl9BnUhHufVRbp51Mn3w0gfUs=; \
    info=<https://atlanta.example.com/atlanta.cert>;alg=ES256;ppt=div
   Identity:  ... L2V4YW1wbGUuY2VydCJ9eyJhdHRlc3QiOiJBIiwiZGVzdCI6 \
   eyJ0biI6IisxMjE1NTU1MTIxMyJ9LCJpYXQiOiIxNDcxMzc1NDE4Iiwib3JpZyI \
   6eyJ0biI64oCdKzEyMTU1 NTUxMjEyIn0sIm9yaWdpZCI6IjEyM2U0NTY3LWU4O \
   ;info =<http://cert.example2.net/example.cert>;alg=ES256; ppt=div
   Contact: Alice <sip:12155551213@example.com;user=phone>
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]

   F7 200 OK VM -> Example.com

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK4523;\
                                    received=192.0.2.101
   Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
   From: Alice <sip:alice@example.com>;tag=kkaz-
   To: Bob <sip:bob@example.com>;tag=3dweggs
   Supported: histinfo
   Call-Id: 12345600@example.com
   CSeq: 1 INVITE
   History-Info: <sip:bob@example.com>;index=1
   History-Info: <sip:sip:sip:12155551212@example.com;user=phone?\
                      Reason=SIP%3Bcause%3D302>;\
                      index=1.1;rc=1
   History-Info: <sip:carol@example.com;cause=480?Reason=SIP%3Bcause%3D\
                 408>;index=1.2;mp=1
   History-Info: <sip:12155551213@example.com;user=phone;cause=480?\
                      Reason=SIP%3Bcause%3D\
                 408>;index=1.2.1;rc=1.2
   History-Info: <sip:vm@example.com;\
                      target=sip:bob%40example.com;cause=480>;\
                      index=1.3;mp=1
   History-Info: <sip:vm@192.0.2.6;\
                      target=sip:bob%40example.com;cause=480>;\
                      index=1.3.1;rc=1.3
   Contact: <sip:vm@192.0.2.6>
   Content-Type: application/sdp
   Content-Length: <appropriate value>

   [SDP Not Shown]


                  Figure 1: Enterprise Voicemail Example




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   The VMS can look at the last hi-entry and finds the target of the
   mailbox by looking at the URI entry in the "target" URI parameter in
   the hi-entry.

3.2.  Consumer Voicemail Example

   In the case of a consumer, when the call is retargeted, it is usually
   to another administrative domain.  The voicemail system in these
   environment typically requires the last called party information to
   determine the appropriate mailbox so an appropriate greeting can be
   provided and the appropriate party notified of the message.

   In this example, Alice calls Bob but Bob has temporarily forwarded
   his phone to his wife Carol.  Carol does not answer the call, thus it
   is forwarded to a VM (voicemail) server (VMS).  In order to determine
   the appropriate mailbox to use for this call, the VMS needs the
   appropriate target for the request.  The last target is determined by
   finding the hi-entry referenced by the index of last hi-entry tagged
   with "mp" for determining the appropriate mailbox.

   If the SIP Identity header field with "div" claims has been added by
   the entities retargeting, it can be ascertained that the call should
   be forwarded to Carol's voicemail prior to forwarding the call to
   voicemail.  The value of the "tn" in the "div" field of the claim
   should match the hi-targeted-to URI in the hi-entry with the hi-index
   matching the "hi" value in the "div" field.

   This hi-entry is used to populate the "target" URI parameter as
   defined in [RFC4458].  Note that some VMSs may also (or instead) use
   the information available in the History-Info headers for custom
   handling of the VM in terms of how and why the called arrived at the
   VMS.



 Alice      example.com       Bob          Carol        VM
 12155551211               12155551212    12155551213

 | INVITE F1    |              |             |          |
 |------------->|              |             |          |
 |              | INVITE  F2   |             |          |
 |              |------------->|             |          |
 |              |              |             |          |
 |  100 Trying  |              |             |          |
 |<-------------| 302 Moved Temporarily F3   |          |
 |              |<-------------|             |          |
 |              |              |             |          |
 |              |      ACK     |             |          |



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 |              |------------->|             |          |
 |              |              |             |          |
 |              | INVITE F4    |             |          |
 |              |--------------------------->|          |
 |              |              |             |          |
 |              |         180 Ringing  F5    |          |
 |              |<---------------------------|          |
 |              |              |             |          |
 | 180 Ringing  |              |             |          |
 |<-------------|              |             |          |
 |              |              |             |          |
 |              |       (timeout)            |          |
 |              |              |             |          |
 |              | INVITE  F6   |             |          |
 |              |-------------------------------------->|
 |              |              |             |          |
 |              |               200 OK  F7              |
 |              |<--------------------------------------|
 |   200 OK     |              |             |          |
 |<-------------|              |             |          |
 |              |              |             |          |
 |                         ACK                          |
 |----------------------------------------------------->|



 F1 INVITE Alice -> Example.com

 INVITE sip:12155551212@example.com;user=phone SIP/2.0
 Via: SIP/2.0/TCP  192.0.2.3:5060;branch=z9hG4bK42t2
 Max-Forward: 70
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-
 To: Bob <sip:12155551212@example.com;user=phone>
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 Contact: Alice <sip:12155551211@e192.0.2.3;user=phone>
 Content-Length: <appropriate value>

 [SDP Not Shown]


 F2 INVITE Example.com -> Bob

 INVITE sip:12155551212@192.0.2.5;user=phone SIP/2.0
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK12s4
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2



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 Max-Forward: 69
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-
 To: Bob <sip:2155551212@example.com;user=phone>
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 History-Info: <sip:12155551212@192.0.2.5>;index=1.1;rc=1
 Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
    joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
    kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
    I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
    q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
    ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
    /biloxi.cert>;alg=ES256
 Contact: Alice <sip:12155551211@192.0.2.3;user=phone>
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]

 F3 302 Moved Temporarily Bob -> Example.com

 SIP/2.0 302 Moved Temporarily
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK12s4;\
                 received=192.0.2.101
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-
 To: Bob <sip:2155551212@example.com;user=phone>;tag=2241s3s-t
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 History-Info: <sip:12155551212@192.0.2.5;user=phone>;index=1.1;rc=1
 Contact: <sip:12155551213@home.example.com;user=phone>;mp=1
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]


 F4 INVITE Example.com -> Carol

 INVITE sip:12155551213@example.com;user=phone SIP/2.0
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK24s5
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
 Max-Forward: 69
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-



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 To: Carol <sip:12155551213@home.example.com;user=phone>
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 History-Info: <sip:12155551212@192.0.2.5;user=phone?\
               Reason=SIP%3Bcause%3D302\
               %3Btext%3D%22Moved%20Temporarily%22>\
               ;index=1.1;rc=1
 History-Info: <sip:12155551213@home.example.com;user=phone>;\
               index=1.2;mp=1
 History-Info: <sip:12155551213@192.0.2.4;user=phone>;index=1.2.1;rc=1.2
 Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
    joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
    kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
    I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
    q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
    ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
    /biloxi.cert>;alg=ES256
 Identity:..sv5CTo05KqpSmtHt3dcEiO/1CWTSZtnG3iV+1nmurLXV/HmtyNS \
   7Ltrg9dlxkWzoeU7d7OV8HweTTDobV3itTmgPwCFjaEmMyEI3d7SyN21yNDo2\
   EROvgtw0Lu5csIppPqOg1uXndzHbG7mR6Rl9BnUhHufVRbp51Mn3w0gfUs=; \
   info=<https://atlanta.example.com/atlanta.cert>;alg=ES256;ppt=div
 Contact: Alice <sip:12155551211@192.0.2.3;user=phone>
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]

 F5 180 Ringing Carol -> Example.com

 SIP/2.0 180 Ringing
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bK24s5;\
                 received=192.0.2.101
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-
 To: Carol <sip:12155551213@home.example.com;user=phone>
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 History-Info: <sip:12155551212@192.0.2.5;user=phone?\
               Reason=SIP%3Bcause%3D302\
               %3Btext%3D%22Moved%20Temporarily%22>\
               ;index=1.1;rc=1
 History-Info: <sip:12155551213@home.example.com;user=phone>;\
                index=1.2;mp=1
 History-Info: <sip:12155551213@192.0.2.4;user=phone>;index=1.2.1;rc=1.2



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 Contact: <sip:12155551213@192.0.2.4;user=phone>
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]

 F6 INVITE Example.com -> VM

 INVITE sip:vm@192.0.2.6;target=sip:sip:12155551213%40home.example.com\
        SIP/2.0
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bKbbg4
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
 Max-Forward: 69
 From: Alice <sip:12155551211@example.com;user=phone>;tag=kkaz-
 To: Carol <sip:12155551213@home.example.com;user=phone>
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:12155551212@example.com;user=phone>;index=1
 History-Info: <sip:12155551212@192.0.2.5;user=phone?\
               Reason=SIP%3Bcause%3D302\
               %3Btext%3D%22Moved%20Temporarily%22>\
               ;index=1.1;rc=1
 History-Info: <sip:12155551213@home.example.com;user=phone>;\
               index=1.2;mp=1
 History-Info: <sip:12155551213@192.0.2.4;user=phone>;index=1.2.1;rc=1.2
 History-Info: <sip:vm@example.com;\
               target=sip:12155551213%40home.example.com;\
               cause=408>;index=1.2.2;mp=1.2
 History-Info: <sip:vm@192.0.2.5;\
               target=sip:12155551213%40home.example.com;\
               cause=408>;index=1.2.2.1;rc=1.2.2
 Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
    joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
    kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
    I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
    q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
    ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
    /biloxi.cert>;alg=ES256
 Identity:..sv5CTo05KqpSmtHt3dcEiO/1CWTSZtnG3iV+1nmurLXV/HmtyNS \
   7Ltrg9dlxkWzoeU7d7OV8HweTTDobV3itTmgPwCFjaEmMyEI3d7SyN21yNDo2\
   EROvgtw0Lu5csIppPqOg1uXndzHbG7mR6Rl9BnUhHufVRbp51Mn3w0gfUs=; \
   info=<https://atlanta.example.com/atlanta.cert>;alg=ES256;ppt=div
 Contact: Alice <sip:12155551211@192.0.2.3;user=phone>
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]



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 F7 200 OK VM -> Example.com

 SIP/2.0 200 OK
 Via: SIP/2.0/TCP proxy.example.com:5060;branch=z9hG4bKbbg4
 Via: SIP/2.0/TCP 192.0.2.3:5060;branch=z9hG4bK42t2
 From: Alice <sip:alice@example.com>;tag=kkaz-
 To: Bob <sip:bob@example.com>;tag=3dweggs
 Supported: histinfo
 Call-Id: 12345600@example.com
 CSeq: 1 INVITE
 History-Info: <sip:bob@example.com>;index=1
 History-Info: <sip:12155551212@example.com;user=phone?\
               Reason=SIP%3Bcause%3D302\
               %3Btext%3D%22Moved%20Temporarily%22>;\
               index=1.1;rc=1
 History-Info: <sip:12155551213@home.example.com;user=phone>;\
               index=1.2;mp=1
 History-Info: <sip:12155551213@192.0.2.4;user=phone>;index=1.2.1;rc=1.2
 History-Info: <sip:vm@example.com;\
               target=sip:12155551213%40home.example.com;\
               cause=408>;index=1.2.2;mp=1.2
 History-Info: <sip:vm@192.0.2.5;\
               target=sip:12155551213%40home.example.com;\
               cause=408>;index=1.2.2.1;rc=1.2.2

 Contact: <sip:12155551213@192.0.2.4;user=phone>
 Content-Type: application/sdp
 Content-Length: <appropriate value>

 [SDP Not Shown]



                   Figure 2: Consumer Voicemail Example

   The VMS can look at the last hi-entry and find the target of the
   mailbox by looking for the "target" URI parameter in the hi-entry and
   the reason by the "cause" URI parameter in the same hi-entry.

4.  Security Considerations

   This document adds no new security considerations beyond those
   specified in [RFC7044] for the History-Info header field and
   [RFC8224] for the Identity header field.







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5.  IANA Considerations

   This document has no IANA considerations.

5.1.  Acknowledgements

6.  Informative References

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <https://www.rfc-editor.org/info/rfc3261>.

   [RFC4458]  Jennings, C., Audet, F., and J. Elwell, "Session
              Initiation Protocol (SIP) URIs for Applications such as
              Voicemail and Interactive Voice Response (IVR)", RFC 4458,
              DOI 10.17487/RFC4458, April 2006,
              <https://www.rfc-editor.org/info/rfc4458>.

   [RFC7044]  Barnes, M., Audet, F., Schubert, S., van Elburg, J., and
              C. Holmberg, "An Extension to the Session Initiation
              Protocol (SIP) for Request History Information", RFC 7044,
              DOI 10.17487/RFC7044, February 2014,
              <https://www.rfc-editor.org/info/rfc7044>.

   [RFC7131]  Barnes, M., Audet, F., Schubert, S., van Elburg, H., and
              C. Holmberg, "Session Initiation Protocol (SIP) History-
              Info Header Call Flow Examples", RFC 7131,
              DOI 10.17487/RFC7131, March 2014,
              <https://www.rfc-editor.org/info/rfc7131>.

   [RFC8224]  Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
              "Authenticated Identity Management in the Session
              Initiation Protocol (SIP)", RFC 8224,
              DOI 10.17487/RFC8224, February 2018,
              <https://www.rfc-editor.org/info/rfc8224>.

   [RFC8225]  Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
              Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
              <https://www.rfc-editor.org/info/rfc8225>.

   [I-D.ietf-stir-passport-divert]
              Peterson, J., "PASSporT Extension for Diverted Calls",
              draft-ietf-stir-passport-divert-04 (work in progress),
              October 2018.





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Author's Address

   Mary Barnes
   iconectiv
   TX
   US

   Email: mary.ietf.barnes@gmail.com











































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