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RFC 8148

Proposed STD
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Next-Generation Vehicle-Initiated Emergency Calls

Part 1 of 2, p. 1 to 21
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Internet Engineering Task Force (IETF)                        R. Gellens
Request for Comments: 8148                    Core Technology Consulting
Category: Standards Track                                       B. Rosen
ISSN: 2070-1721                                            NeuStar, Inc.
                                                           H. Tschofenig
                                                              Individual
                                                                May 2017


           Next-Generation Vehicle-Initiated Emergency Calls

Abstract

   This document describes how to use IP-based emergency services
   mechanisms to support the next generation of emergency calls placed
   by vehicles (automatically in the event of a crash or serious
   incident, or manually invoked by a vehicle occupant) and conveying
   vehicle, sensor, and location data related to the crash or incident.
   Such calls are often referred to as "Automatic Crash Notification"
   (ACN), or "Advanced Automatic Crash Notification" (AACN), even in the
   case of manual trigger.  The "Advanced" qualifier refers to the
   ability to carry a richer set of data.

   This document also registers a MIME media type and Emergency Call
   Data Type for the vehicle, sensor, and location data (often referred
   to as "crash data" even though there is not necessarily a crash) and
   an INFO package to enable carrying this and related data in SIP INFO
   requests.  An external specification for the data format, contents,
   and structure is referenced in this document.

   This document reuses the technical aspects of next-generation Pan-
   European eCall (a mandated and standardized system for emergency
   calls by in-vehicle systems (IVSs) within Europe and other regions).
   However, this document specifies use of a different set of vehicle
   (crash) data, specifically, the Vehicle Emergency Data Set (VEDS)
   rather than the eCall Minimum Set of Data (MSD).  This document is an
   extension of the IETF eCall document, with the primary differences
   being that this document makes the MSD data set optional and VEDS
   mandatory, and it adds attribute values to the metadata/control
   object to permit greater functionality.  This document registers a
   new INFO package (identical to that registered for eCall but with the
   addition of the VEDS MIME type).  This document also describes legacy
   (circuit-switched) ACN systems and their migration to next-generation
   emergency calling, to provide background information and context.

[Page 2] 
Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8148.

Copyright Notice

   Copyright (c) 2017 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
   (http://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
   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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  Document Scope  . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  Overview of Legacy Deployment Models  . . . . . . . . . . . .   8
   5.  Migration to Next Generation  . . . . . . . . . . . . . . . .  10
   6.  Vehicle Data  . . . . . . . . . . . . . . . . . . . . . . . .  13
   7.  Data Transport  . . . . . . . . . . . . . . . . . . . . . . .  14
   8.  Call Setup  . . . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  New Metadata/Control Values . . . . . . . . . . . . . . . . .  17
     9.1.  New Values for the "action" Attribute . . . . . . . . . .  18
     9.2.  Example <request> Element . . . . . . . . . . . . . . . .  19
     9.3.  The <ack> Element . . . . . . . . . . . . . . . . . . . .  19
     9.4.  The <capabilities> Element  . . . . . . . . . . . . . . .  20
   10. Test Calls  . . . . . . . . . . . . . . . . . . . . . . . . .  21
   11. Example Call Initiation . . . . . . . . . . . . . . . . . . .  22
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  27
   13. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  28
   14. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  28
     14.1.  MIME Media Type Registration for
            application/EmergencyCall.VEDS+xml . . . . . . . . . . .  28
     14.2.  Registration of the "VEDS" Entry in the Emergency Call
            Data Types Registry  . . . . . . . . . . . . . . . . . .  30
     14.3.  New Action Values  . . . . . . . . . . . . . . . . . . .  30
     14.4.  Emergency Call Static Messages Registry  . . . . . . . .  31
     14.5.  Emergency Call Vehicle Lamp IDs Registry . . . . . . . .  32
     14.6.  Emergency Call Vehicle Camera IDs Registry . . . . . . .  33
     14.7.  The EmergencyCallData.VEDS INFO Package  . . . . . . . .  35
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  38
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  38
     15.2.  Informative references . . . . . . . . . . . . . . . . .  39
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40

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1.  Introduction

   Emergency calls made by in-vehicle systems (e.g., automatically in
   the event of a crash or serious incident or manually by a vehicle
   occupant) assist in significantly reducing road deaths and injuries
   by allowing emergency services to respond quickly and appropriately
   to the specifics of the incident, often with better location
   accuracy.

   Drivers often have a poor location awareness, especially outside of
   major cities, at night, and when away from home (especially abroad).
   In the most crucial cases, the victim(s) might not be able to call
   because they have been injured or trapped.

   For more than two decades, some vehicles have been equipped with
   telematics systems that, among other features, place an emergency
   call automatically in the event of a crash or manually in response to
   an emergency call button.  Such systems generally have on-board
   location determination systems that make use of satellite-based
   positioning technology, inertial sensors, gyroscopes, etc., which can
   provide an accurate position for the vehicle.  Such built-in systems
   can take advantage of the benefits of being integrated into a
   vehicle, such as more power capacity, ability to have larger or
   specialized antenna, ability to be engineered to avoid or minimize
   degradation by vehicle glass coatings, interference from other
   vehicle systems, etc.  Thus, the Public Safety Answering Point (PSAP)
   can be provided with a good estimate of where the vehicle is during
   an emergency.  Vehicle manufacturers are increasingly adopting such
   systems, both for the safety benefits and for the additional features
   and services they enable (e.g., remote engine diagnostics, remote
   door unlock, stolen vehicle tracking and disabling, etc.).

   A common term for such systems is Automatic Crash Notification (ACN)
   or Advanced Automatic Crash Notification (AACN).  Sometimes the word
   "Collision" is used instead of "Crash."  In this document, "ACN" is
   used as a general term.  ACN systems transmit some amount of data
   specific to the incident, referred to generally as "crash data" (the
   term is commonly used even though there might not have been a crash).
   While different systems transmit different amounts of crash data,
   standardized formats, structures, and mechanisms are needed to
   provide interoperability among systems and PSAPs.

   As of the date of this document, currently deployed in-vehicle
   telematics systems are circuit-switched and lack a standards-based
   ability to convey crash data directly to the PSAP (generally relying
   on either a human advisor or an automated text-to-speech system to
   provide the PSAP call taker with some crash data orally, or in some
   cases via a proprietary mechanism).  In most cases, the PSAP call

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   taker needs to first realize that the call is related to a vehicle
   incident, and then listen to the data and transcribe it.  Circuit-
   switched ACN systems are referred to here as "CS-ACN".

   The transition to next-generation emergency calling provides an
   opportunity to vastly improve the scope, breadth, reliability, and
   usefulness of crash data by transmitting a standardized set during
   call setup; the data can be processed by the PSAP in an integrated,
   automated way and made available to the call taker at call
   presentation.  It also provides the ability for the call taker to
   request that a vehicle take certain actions, such as flashing lights
   or unlocking doors.  In addition, vehicle manufacturers are provided
   an opportunity to take advantage of the same standardized mechanisms
   for data transmission and request processing for internal use if they
   wish (such as telemetry between the vehicle and a service center for
   both emergency and non-emergency uses, including location-based
   services, multimedia entertainment systems, remote door unlocking,
   remote diagnostics, and roadside assistance applications).

   Next-generation ACN provides an opportunity for such calls to be
   recognized and processed as such during call setup, and routed to an
   equipped PSAP where the vehicle data is available to assist the call
   taker in assessing and responding to the situation.  Next-generation
   (IP-based) ACN systems are referred to here as NG-ACN.

   An ACN call can be initiated by a vehicle occupant or automatically
   initiated by vehicle systems in the event of a serious incident.
   (The "A" in "ACN" does stand for "Automatic", but the term is broadly
   used to refer to the class of calls that are placed by an in-vehicle
   system (IVS) or by Telematics Service Providers (TSPs) and that carry
   incident-related data as well as voice.)  Automatically triggered
   calls indicate a car crash or some other serious incident (e.g., a
   fire).  Manually triggered calls include reports of observed crashes
   or serious hazards (such as impaired drivers or roadway debris),
   requests for medical assistance, etc.

   The Association of Public-Safety Communications Officials (APCO) and
   the National Emergency Number Association (NENA) have jointly
   developed a standardized set of incident-related vehicle data for ACN
   use, called the Vehicle Emergency Data Set (VEDS) [VEDS].  Such data
   is often referred to as crash data although it is applicable in
   incidents other than crashes.

   This document describes how the IETF mechanisms for IP-based
   emergency calls are used to provide the realization of next-
   generation ACN.  Although this specification is designed with the
   requirements for North America ACN in mind (and both APCO and NENA
   are based in the U.S.), it is specified generically such that the

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   technology can be reused or extended to suit requirements in other
   regions.

   This document reuses the technical aspects of next-generation Pan-
   European eCall (a mandated and standardized system for emergency
   calls by in-vehicle systems within Europe), as described in
   [RFC8147].  However, this document specifies use of a different set
   of vehicle (crash) data, specifically, VEDS rather than the eCall
   Minimum Set of Data (MSD).  This document is an extension of
   [RFC8147], with the differences being that this document makes the
   MSD data set optional and VEDS mandatory, and it adds new attribute
   values to the metadata/control object defined in that document.  This
   document also registers a new INFO package (identical to that defined
   in [RFC8147] with the addition of the VEDS MIME type).

   This document registers the application/EmergencyCallData.VEDS+xml
   MIME media type, the VEDS Emergency Call Data Type, and the
   EmergencyCallData.VEDS INFO package to enable carrying this and
   related data in SIP INFO requests.

   Section 6 introduces VEDS.  Section 7 describes how VEDS data and
   metadata/control blocks are transported within NG-ACN calls.
   Section 8 describes how such calls are placed.

   These mechanisms are used to place emergency calls that are
   identifiable as ACN calls and that carry standardized crash data in
   an interoperable way.

   Calls by in-vehicle systems are placed using cellular networks, which
   might ignore location information sent by an originating device in an
   emergency call INVITE, instead substituting their own location
   information (although often determined in cooperation with the
   originating device).  Standardized crash data structures typically
   include location as determined by the IVS.  A benefit of this is that
   it allows the PSAP to see both the location as determined by the
   cellular network and the location as determined by the IVS.

   This specification inherits the ability to utilize test call
   functionality from Section 15 of [RFC6881].

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

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   This document reuses terminology defined in Section 3 of [RFC5012].
   Additionally, we use the following abbreviations:

      3GPP:    3rd Generation Partnership Project

      AACN:    Advanced Automatic Crash Notification

      ACN:     Automatic Crash Notification

      APCO:    Association of Public-Safety Communications Officials

      EENA:    European Emergency Number Association

      ESInet:  Emergency Services IP network

      GNSS:    Global Navigation Satellite System (which includes
               various systems such as the Global Positioning System or
               GPS)

      IVS:     In-Vehicle System

      MNO:     Mobile Network Operator

      MSD:     Minimum Set of Data

      NENA:    National Emergency Number Association

      NG:      Next Generation

      POTS:    Plain Old Telephone Service (normal, circuit-switched
               voice calls)

      PSAP:    Public Safety Answering Point

      TSP:     Telematics Service Provider

      VEDS:    Vehicle Emergency Data Set

   Because the endpoints of a next-generation ACN call are a PSAP and
   either an IVS or a TSP, to avoid repetitively writing "IVS or TSP",
   the term "IVS" is used to represent either an IVS or a TSP when
   discussing signaling behavior (e.g., sending VEDS data, sending a SIP
   INVITE request, receiving a SIP INFO request, etc.).

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3.  Document Scope

   This document is focused on how an ACN emergency call is set up and
   incident-related data (including vehicle, sensor, and location data)
   is transmitted to the PSAP using IETF specifications.  For the direct
   model, this is the end-to-end description (between the vehicle and
   the PSAP).  For the TSP model, this describes the call leg between
   the TSP and the PSAP, leaving the call leg between the vehicle and
   the TSP up to the entities involved (i.e., IVS and TSP vendors) who
   are free to use the same mechanism for both legs, or not.

   Note that Europe has a mandated and standardized system for emergency
   calls by in-vehicle systems.  This Pan-European system is known as
   "eCall" and is the subject of a separate document, [RFC8147], which
   this document builds on.  Vehicles designed to operate in multiple
   regions might need to support eCall as well as NG-ACN as described
   here.  A vehicle IVS might determine whether to use eCall or ACN by
   first determining the region or country in which it is located (e.g.,
   from a GNSS location estimate and/or identity of or information from
   an MNO).  If other regions adopt other data formats, a multi-region
   vehicle might need to support those as well.  This document adopts
   the call setup and other technical aspects of [RFC8147], which uses
   [RFC7852]; this makes it straightforward to use a different data set
   while keeping other technical aspects unchanged.  Hence, both next-
   generation eCall (NG-eCall) and the NG-ACN mechanism described here
   are compatible, differing primarily in the specific data block that
   is sent (the eCall MSD in the case of NG-eCall and VEDS in this
   document) and some additions to the metadata/control data block.  If
   other regions adopt their own vehicle data sets, this can be
   similarly accommodated without changing other technical aspects.
   Note that any additional data formats require a new INFO package to
   permit transport within SIP INFO requests.

4.  Overview of Legacy Deployment Models

   Legacy (circuit-switched) systems for placing emergency calls by
   in-vehicle systems generally have some ability to convey at least
   location and in some cases telematics data to the PSAP.  Most such
   systems use one of three architectural models, which are described
   here as: "TSP", "direct", and "paired".  These three models are
   illustrated below.

   In the TSP model, both emergency and routine TSP service calls are
   placed to a TSP; a proprietary technique (e.g., a proprietary in-band
   modem) is used for data transfer between the TSP and the vehicle.

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   In an emergency, typically a TSP agent verifies the emergency,
   bridges in the PSAP, and communicates location, crash data (such as
   impact severity and trauma prediction), and other data (such as the
   vehicle description) to the PSAP call taker orally (in some cases, a
   proprietary out-of-band interface is used).  Since the TSP knows the
   location of the vehicle (from on-board GNSS and sensors), location-
   based routing is usually used to route to the appropriate PSAP.  In
   some cases, the TSP is able to transmit location automatically, using
   similar techniques as for wireless calls.  A three-way voice call is
   generally established between the vehicle, the TSP, and the PSAP,
   allowing communication between the PSAP call taker, the TSP agent,
   and the vehicle occupants (who might be unconscious).

      ///----\\\  proprietary  +-----+  911 trunk or POTS   +------+
     ||| IVS |||-------------->| TSP |--------------------->| PSAP |
      \\\----///  crash data   +-----+  location via trunk  +------+

                        Figure 1: Legacy TSP Model

   In the paired model, the IVS uses a local link (typically Bluetooth
   [Bluetooth]) with a previously paired handset to establish an
   emergency call with the PSAP (by dialing a standard emergency number;
   9-1-1 in North America) and then communicates location data to the
   PSAP via text-to-speech; crash data might or might not be conveyed
   also using text-to-speech.  Some such systems use an automated voice
   prompt menu for the PSAP call taker (e.g., "this is an automatic
   emergency call from a vehicle; press 1 to open a voice path to the
   vehicle; press 2 to hear the location read out") to allow the call
   taker to request location data via text-to-speech.

      ///----\\\   +----+   911/etc. voice call via handset  +------+
     ||| IVS |||-->| HS |----------------------------------->| PSAP |
      \\\----///   +----+   location via text-to-speech      +------+

   (Note: "HS" is handset.)

                       Figure 2: Legacy Paired Model

   In the direct model, the IVS directly places an emergency call with
   the PSAP by dialing a standard emergency number (9-1-1 in North
   America).  Such systems might communicate location data to the PSAP
   via text-to-speech; crash data might or might not be conveyed using
   text-to-speech.  Some such systems use an automated voice prompt menu
   (e.g., "this is an automatic emergency call from a vehicle; press 1
   to open a voice path to the vehicle; press 2 to hear the location
   read out") to allow the call taker to request location data via
   text-to-speech.

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      ///----\\\      911/etc. voice call via IVS         +------+
     ||| IVS  |||---------------------------------------->| PSAP |
      \\\----///     location via text-to-speech          +------+

                       Figure 3: Legacy Direct Model

5.  Migration to Next Generation

   The migration of emergency calls placed by in-vehicle systems to
   next-generation (all-IP) technology per this document provides a
   standardized mechanism to identify such calls and to convey crash
   data with the call setup, as well as enabling additional
   communications modalities and enhanced functionality.  This allows
   ACN calls and crash data to be automatically processed by the PSAP
   and made available to the call taker in an integrated, automated way.
   Because the crash data is carried in the initial SIP INVITE (per
   [RFC7852]) the PSAP can present it to the call taker simultaneously
   with the appearance of the call.  The PSAP can also process the data
   to take other actions (e.g., if multiple calls from the same location
   arrive when the PSAP is busy and a subset of them are NG-ACN calls, a
   PSAP might choose to store the information and reject the calls,
   since the IVS will receive confirmation that the information has been
   successfully received; a PSAP could also choose to include a message
   stating that it is aware of the incident and responders are on the
   way, and a PSAP could call the vehicle back when a call taker is
   available).

   The migration of origination devices and networks, PSAPs, emergency
   services networks, and other telephony environments to next
   generation technology provides enhanced interoperability and
   functionality, especially for emergency calls carrying additional
   data such as vehicle crash data.  (In the U.S., a network
   specifically for emergency responders is being developed.  This
   network, FirstNet, will be next generation from the start, enhancing
   the ability for data exchange between PSAPs and responders.)

   NG-ACN calls can be recognized as such during call set-up; they can
   be routed to a PSAP that is prepared both technically and
   operationally to handle such calls, and the vehicle-determined
   location and crash data can be processed automatically by the PSAP
   and made available to the call taker simultaneously with the call
   appearance.  Enhanced functionality includes the ability for the PSAP
   call taker to request the vehicle to take an action, such as sending
   an updated set of data, conveying a message to the occupants,
   flashing lights, unlocking doors, etc.

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   Vehicle manufacturers using the TSP model can choose to take
   advantage of the same mechanism to carry telematics data and requests
   and responses between the vehicle and the TSP for both emergency and
   non-emergency calls as are used for the interface with the PSAP.

   An IVS establishes a next-generation emergency call (see [RFC6443]
   and [RFC6881]) with an initial INVITE containing a Request-URI
   indicating an ACN emergency call and Call-Info header fields
   indicating that both vehicle crash and capabilities data are
   included; the IVS typically does not perform routing or location
   queries (relying on the MNO for this).

   [RFC8147] registers new service URN children within the "sos"
   subservice.  These URNs request NG-ACN resources and differentiate
   between manually and automatically triggered NG-ACN calls (which
   might be subject to different treatment depending on policy).  The
   two service URNs registered in [RFC8147] are
   "urn:service:sos.ecall.automatic" and "urn:service:sos.ecall.manual".
   The same service URNs are used for ACN as for eCall since in any
   region only one of these is supported, making a distinction
   unnecessary.  (Further, PSAP equipment might support multiple data
   formats, allowing a PSAP to handle a vehicle that erroneously sent
   the wrong data object.)

   Note that in North America, routing queries performed by clients
   outside of an ESInet typically treat all sub-services of "sos"
   identically to "sos" with no sub-service.  However, the Request-URI
   header field retains the full sub-service; route and handling
   decisions within an ESInet or PSAP can take the sub-service into
   account.  For example, in a region with multiple cooperating PSAPs,
   an NG-ACN call might be routed to a PSAP that is NG-ACN capable, or
   one that specializes in vehicle-related incidents.

   Migration of the three architectural models to next generation
   (all-IP) is described below.

   In the TSP model, the IVS transmits crash and location data to the
   TSP either by reusing the mechanisms and data objects described in
   this document or by using a proprietary mechanism.  In an emergency,
   the TSP bridges in the PSAP, and the TSP transmits crash and other
   data to the PSAP using the mechanisms and data objects described in
   this document.  There is a three-way call between the vehicle, the
   TSP, and the PSAP, allowing communication between the PSAP call
   taker, the TSP agent, and the vehicle occupants (who might be
   unconscious).  The TSP relays PSAP requests and vehicle responses.

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                   proprietary
     ///----\\\    or standard     +-----+     standard       +------+
    ||| IVS |||------------------->| TSP |------------------->| PSAP |
     \\\----///  crash+other data  +-----+  crash+other data  +------+

                    Figure 4: Next-Generation TSP Model

   The vehicle manufacturer and the TSP can choose to use the same
   mechanisms and data objects on the left call leg in Figure 4 as on
   the right.  (Note that the TSP model can be more difficult when the
   vehicle is in a different country than the TSP (e.g., a US resident
   driving in Canada) because of the additional complexity in choosing
   the correct PSAP based on vehicle location performed by a TSP in a
   different country.)

   In the direct model, the IVS communicates crash data to the PSAP
   directly using the mechanisms and data objects described in this
   document.

     ///----\\\           NG emergency call              +------+
    ||| IVS |||----------------------------------------->| PSAP |
     \\\----///          crash + other data              +------+

                  Figure 5: Next-Generation Direct Model

   In the paired model, the IVS uses a local link to a previously paired
   handset to establish an emergency call with the PSAP; it is unclear
   what facilities are or will be available for transmitting crash data
   through the link to the handset for inclusion in an NG emergency call
   and receiving additional data items from the response.  Hence,
   manufacturers that use the paired model for legacy calls might choose
   to adopt either the direct or TSP model for next-generation calls.

      ///----\\\   (undefined)    +----+      standard        +------+
     ||| IVS |||----------------->| HS |--------------------->| PSAP |
      \\\----///   (undefined)    +----+  crash + other data  +------+

                  Figure 6: Next-Generation Paired Model

   Regardless of model, if the call is routed to a PSAP that is not
   NG-ACN capable, the PSAP ignores (or does not receive) the vehicle
   data.  This is detectable by the IVS or TSP when the status response
   to the INVITE (e.g., 200 OK) lacks a metadata/control structure
   acknowledging receipt of the data [RFC8147].  The IVS or TSP then
   proceeds as it would for a CS-ACN call (e.g., oral conveyance of
   data).

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6.  Vehicle Data

   APCO and NENA have jointly developed a standardized set of incident-
   related vehicle data for ACN use, called the Vehicle Emergency Data
   Set (VEDS) [VEDS].  Such data is often referred to as crash data
   although it is applicable in incidents other than crashes.

   VEDS provides a standard data set for the transmission, exchange, and
   interpretation of vehicle-related data.  A standard data format
   allows the data to be generated by an IVS or TSP and interpreted by
   PSAPs, emergency responders, and medical facilities.  It includes
   incident-related information such as airbag deployment, location and
   compass orientation of the vehicle, spatial orientation of the
   vehicle (e.g., upright, on a side, roof, or bumper), sensor data that
   can indicate the potential severity of the crash and the likelihood
   of severe injuries to the vehicle occupants, etc.  This data better
   informs the PSAP and emergency responders as to the type of response
   that might be needed.  Some of this information has been included in
   U.S. government guidelines for field triage of injured patients
   [triage-2008] [triage-2011].  These guidelines are designed to help
   responders identify the potential existence of severe internal
   injuries and to make critical decisions about how and where a patient
   needs to be transported.

   VEDS is an XML structure (see [VEDS]) transported in SIP using the
   application/EmergencyCallData.VEDS+xml MIME media type.

   If new data blocks are needed (e.g., in other regions or for enhanced
   data), the steps required during standardization are briefly
   summarized below:

   o  A set of data is standardized by a Standards Development
      Organization (SDO) or appropriate organization.

   o  A MIME media type for the crash data set is registered with IANA

      *  If the data is specifically for use in emergency calling, the
         MIME media type is normally under the application type with a
         subtype starting with EmergencyCallData.

      *  If the data format is XML, then by convention the name has a
         suffix of "+xml".

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   o  The item is registered in the "Emergency Call Data Types"
      registry, as defined in Section 11.1.9 of [RFC7852].

      *  For emergency-call-specific formats, the registered name is the
         root of the MIME media type (not including the
         EmergencyCallData prefix and any suffix such as "+xml") as
         described in Section 4.1 of [RFC7852].

   o  A new INFO package is registered that permits carrying the new
      media type, the metadata/control object (defined in [RFC8147]),
      and for compatibility, the MSD and VEDS objects, in SIP INFO
      requests.

7.  Data Transport

   [RFC7852] establishes a general mechanism for including blocks of
   data within a SIP emergency call.  This document makes use of that
   mechanism.  This document also registers an INFO package (in
   Section 14.7) to enable NG-ACN-related data blocks to be carried in
   SIP INFO requests (per [RFC6086], new SIP INFO method usages require
   the definition of an INFO package).

   VEDS is an XML structure defined by APCO and NENA [VEDS].  It is
   carried in a body part with MIME media type application/
   EmergencyCallData.VEDS+xml.

   An IVS transmits a VEDS data block (see [VEDS]) by including it as a
   body part of a SIP message per [RFC7852].  The body part is
   identified by its MIME media type (application/
   EmergencyCallData.VEDS+xml) in the Content-Type header field of the
   body part.  The body part is assigned a unique identifier that is
   listed in a Content-ID header field in the body part.  The SIP
   message is marked as containing the VEDS data by adding (or appending
   to) a Call-Info header field at the top level of the SIP message.
   This Call-Info header field contains a Content Identifier (CID) URL
   referencing the body part's unique identifier and a "purpose"
   parameter identifying the data as a VEDS data block per the
   "Emergency Call Data Types" registry entry; the "purpose" parameter's
   value is "EmergencyCallData.VEDS".  A VEDS data block is carried in a
   SIP INFO request by using the INFO package defined in Section 14.7.

   A PSAP or IVS transmits a metadata/control object (see [RFC8147]) by
   including it in a SIP message as a MIME body part per [RFC7852].  The
   body part is identified by its MIME media type (application/
   EmergencyCallData.Control+xml) in the Content-Type header field of
   the body part.  The body part is assigned a unique identifier that is
   listed in a Content-ID header field in the body part.  The SIP
   message is marked as containing the metadata/control block by adding

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   (or appending to) a Call-Info header field at the top level of the
   SIP message.  This Call-Info header field contains a CID URL
   referencing the body part's unique identifier and a "purpose"
   parameter identifying the data as a metadata/control block per the
   "Emergency Call Data Types" registry entry; the "purpose" parameter's
   value is "EmergencyCallData.Control".  A metadata/control object is
   carried in a SIP INFO request by using the INFO package defined in
   Section 14.7.

   A body part containing a VEDS or metadata/control object has a
   Content-Disposition header field value containing "By-Reference" and
   is always enclosed in a multipart body part (even if it would
   otherwise be the only body part in the SIP message).

   An IVS initiating an NG-ACN call includes in the initial INVITE a
   VEDS data block and a metadata/control object informing the PSAP of
   its capabilities.  The VEDS and metadata/control body parts (and
   Presence Information Data Format Location Object (PIDF-LO)) have a
   Content-Disposition header field with the value "By-Reference;
   handling=optional".  Specifying handling=optional prevents the INVITE
   from being rejected if it is processed by a legacy element (e.g., a
   gateway between SIP and circuit-switched environments) that does not
   understand the VEDS or metadata/control (or PIDF-LO) objects.  The
   PSAP creates a metadata/control object acknowledging receipt of the
   VEDS data and includes it in the SIP final response to the INVITE.
   The metadata/control object is not included in provisional (e.g.,
   180) responses.

   If the IVS receives an acknowledgment for a VEDS data object with
   received=false, this indicates that the PSAP was unable to properly
   decode or process the VEDS.  The IVS action is not defined (e.g., it
   might only log an error).  Since the PSAP is able to request an
   updated VEDS during the call, if an initial VEDS is unsatisfactory in
   any way, the PSAP can choose to request another one.

   A PSAP can request that the vehicle send an updated VEDS data block
   during a call.  To do so, the PSAP creates a metadata/control object
   requesting VEDS data and includes it as a body part of a SIP INFO
   request sent within the dialog.  The IVS then includes an updated
   VEDS data object as a body part of a SIP INFO request and sends it
   within the dialog.  If the IVS is unable to send the VEDS for any
   reason, it instead sends a metadata/control object containing an
   <ack> element acknowledging the request and containing an
   <actionResult> element with the "success" parameter set to "false"
   and a "reason" parameter (and optionally a "details" parameter)
   indicating why the request cannot be accomplished.  Per [RFC6086],
   metadata/control objects and VEDS data are sent using the INFO
   package defined in Section 14.7.  In addition, to align with the way

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   a VEDS or metadata/control block is transmitted in a SIP message
   other than a SIP INFO request, one or more Call-Info header fields
   are included in the SIP INFO request referencing the VEDS or
   metadata/control block.  See Section 14.7 for more information on the
   use of SIP INFO requests within NG-ACN calls.

   Any metadata/control object sent by a PSAP can request that the
   vehicle perform an action (such as sending a data block, flashing
   lights, providing a camera feed, etc.).  The IVS sends an
   acknowledgment for any request other than a successfully executed
   send-data action.  Multiple requests with the same "action:" value
   MUST be sent in separate metadata/control body parts (to avoid any
   ambiguity in the acknowledgment).  For each metadata/control block
   received containing one or more <request> elements (except for
   successfully executed send-data requests), the IVS sends a metadata/
   control object containing an <ack> element acknowledging the received
   metadata/control block, containing an <actionResult> element per
   <request> element.

   If the IVS is aware that VEDS data it sent previously has changed, it
   MAY send an unsolicited VEDS in any convenient SIP message, including
   a SIP INFO request during the call.  The PSAP sends an acknowledgment
   for an unsolicited VEDS object; if the IVS sent the unsolicited VEDS
   in a SIP INFO request, the acknowledgment is sent in a new SIP INFO
   request; otherwise, it is sent in the reply to the SIP request
   containing the VEDS.

8.  Call Setup

   An IVS initiating an NG-ACN call sends a SIP INVITE request using one
   of the SOS sub-services "SOS.ecall.automatic" or "SOS.ecall.manual"
   in the Request-URI.  This SIP INVITE request includes standard sets
   of both crash and capabilities data as described in Section 7.

   Entities along the path between the vehicle and the PSAP are able to
   identify the call as an ACN call and handle it appropriately.  The
   PSAP is able to identify the crash and capabilities data included in
   the SIP INVITE request by examining the Call-Info header fields for
   "purpose" parameters whose values start with EmergencyCallData.  The
   PSAP is able to access the data it is capable of handling and is
   interested in by checking the "purpose" parameter values.

   This document extends [RFC8147] by reusing the call setup and other
   normative requirements with the exception that in this document,
   support for the eCall MSD is OPTIONAL and support for VEDS is
   REQUIRED.  This document also adds new attribute values to the
   metadata/control object defined in [RFC8147].

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9.  New Metadata/Control Values

   This document adds new attribute values to the metadata/control
   structure defined in [RFC8147].

   In addition to the base usage from the PSAP to the IVS to acknowledge
   receipt of crash data, the <ack> element is also contained in a
   metadata/control block sent by the IVS to the PSAP.  This is used by
   the IVS to acknowledge receipt of a request by the PSAP and indicate
   if the request was carried out when that request would not otherwise
   be acknowledged (if the PSAP requests the vehicle to send data and
   the vehicle does so, the data serves as a success acknowledgment);
   see Section 8 for details.

   The <capabilities> element is used in a metadata/control block sent
   from the IVS to the PSAP (e.g., in the initial INVITE) to inform the
   PSAP of the vehicle capabilities.  Child elements contain all actions
   and data types supported by the vehicle and all available lamps
   (lights) and cameras.

   New request values are added to the <request> element to enable the
   PSAP to request the vehicle to perform additional actions.

   Mandatory Actions (the IVS and the PSAP MUST support):

   o  Transmit data object (VEDS MUST be supported; MSD MAY be
      supported)

   Optional Actions (the IVS and the PSAP MAY support):

   o  Display and/or play static (pre-defined) message
   o  Display and/or speak dynamic text (text supplied in action)
   o  Flash or turn on or off a lamp (light)
   o  Honk horn
   o  Lock or unlock doors
   o  Enable a camera

   The <ack> element indicates the object being acknowledged (i.e., a
   data object or a metadata/control block containing <request>
   elements) and reports success or failure.

   The <capabilities> element has child <request> elements indicating
   the actions (including data types, lamps (lights), and cameras)
   supported by the IVS.

   The <request> element contains attributes to indicate the request and
   to supply any needed information, and it MAY contain a <text> child
   element to contain the text for a dynamic message.  The "action"

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   attribute is mandatory and indicates the specific action.  [RFC8147]
   established an IANA registry to contain the allowed values; this
   document adds new values to that registry in Table 1.

9.1.  New Values for the "action" Attribute

   The following new "action" values are defined:

   msg-static:  displays or plays a pre-defined message (translated as
      appropriate for the language of the vehicle's interface).  A
      registry is created in Section 14.4 for messages and their IDs.
      Vehicles include the highest registered message in their
      <capabilities> element to indicate support for all messages up to
      and including the indicated value.  A registry of message
      identification values is defined in Section 14.4.  There is only
      one static message initially defined (listed in Table 2).  Because
      all compliant vehicles are expected to support all static messages
      translated into all languages supported by the vehicle, it is
      important to limit the number of such messages.  Therefore, this
      registry operates under "Specification Required" rules as defined
      in [RFC5226], which requires a stable, public document and implies
      expert review of the publication.

   msg-dynamic:  displays or speaks (via text-to-speech) a message
      contained in a child <text> element within the request.

   honk:  sounds the horn.

   lamp:  flashes a lamp (light) or turns it on or off.  The lamp is
      identified by a lamp ID token contained in an "element-id"
      attribute of the request.  The desired state of the lamp is either
      "on", "off", or "flash" as indicated in a "requested-state"
      attribute.  The duration of the lamp's requested state is
      specified in a "persistence" attribute.  A registry of lamp
      identification values is defined in Section 14.5.  The initial
      values (listed in Table 3) are head, interior, fog-front,
      fog-rear, brake, brake-center, position-front, position-rear,
      turn-left, turn-right, and hazard.

   enable-camera:  adds a one-way media stream (established via SIP
      re-INVITE sent by the vehicle) to enable the PSAP call taker to
      view a feed from a camera.  A registry of camera identification
      values is defined in Section 14.6.  The initial values (listed in
      Table 4) are backup, left-rear, right-rear, forward, rear-wide,
      lane, interior, night-front, night-rear, night-left, and night-
      right.

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   door-lock:  locks or unlocks all door locks.  A "requested-state"
      attribute contains either "locked" or "unlocked" to indicate if
      the doors are to be locked or unlocked.

   Note that there is no "request" action to play dynamic media (such as
   an audio message).  The PSAP can send a SIP re-INVITE to establish a
   one-way media stream for this purpose.

9.2.  Example <request> Element

       <?xml version="1.0" encoding="UTF-8"?>
       <EmergencyCallData.Control
           xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

       <request action="send-data" datatype="VEDS"/>
       <request action="lamp" element-id="hazard"
                requested-state="flash" persistence="PT1H"/>
       <request action="msg-static" int-id="1"/>
       <request action="msg-dynamic">
           <text>Remain calm.  Help is on the way.</text>
       </request>

       </EmergencyCallData.Control>

                        Figure 7: <request> Example

9.3.  The <ack> Element

   The <ack> element is transmitted by the PSAP to acknowledge
   unsolicited data sent by the IVS and transmitted by the IVS to
   acknowledge receipt of a <request> element other than a successfully
   performed "send-data" request (e.g., a request to display a message
   to the vehicle occupants is acknowledged, but a request to transmit
   VEDS data is not, since the transmitted VEDS serves as
   acknowledgment).  An <ack> element sent by an IVS references the
   unique ID of the metadata/control object containing the request(s),
   and for each request being acknowledged, it indicates whether the
   request was successfully performed, and if not, it indicates why not.

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9.3.1.  Examples of the <ack> Element

       <?xml version="1.0" encoding="UTF-8"?>
       <EmergencyCallData.Control
           xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

       <ack ref="1234567890@atlanta.example.com">
           <actionResult action="msg-dynamic" success="true"/>
           <actionResult action="lamp" success="false" reason="unable"
                         details="The requested lamp is inoperable"/>
       </ack>

       </EmergencyCallData.Control>

                 Figure 8: Example <ack> from IVS to PSAP

9.4.  The <capabilities> Element

   The <capabilities> element [RFC8147] is transmitted by the IVS to
   indicate its capabilities to the PSAP.

   The <capabilities> element contains a <request> child element per
   action supported by the vehicle.  The vehicle MUST support sending
   the VEDS data object and so includes at a minimum a <request> child
   element with the "action" attribute set to "send-data" and the
   "supported-values" attribute containing all data blocks supported by
   the IVS, which MUST include "VEDS".  All other actions are OPTIONAL.

   If the "msg-static" action is supported, a <request> child element
   with the "action" attribute set to "msg-static" is included, with the
   "int-id" attribute set to the highest supported static message
   supported by the vehicle.  A registry is created in Section 14.4 to
   map "int-id" values to static text messages.  By sending the highest
   supported static message number in its <capabilities> element, the
   vehicle indicates its support for all static messages in the registry
   up to and including that value.

   If the "lamp" action is supported, a <request> child element with the
   "action" attribute set to "lamp" is included, with the "supported-
   values" attribute set to all supported lamp IDs.  A registry is
   created in Section 14.5 to contain lamp ID values.

   If the "enable-camera" action is supported, a <request> child element
   with the "action" attribute set to "enable-camera" is included, with
   the "supported-values" attribute set to all supported camera IDs.  A
   registry is created in Section 14.6 to contain camera ID values.

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9.4.1.  Example <capabilities> Element

       <?xml version="1.0" encoding="UTF-8"?>
       <EmergencyCallData.Control
           xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

       <capabilities>
           <request action="send-data" supported-values="VEDS"/>
           <request action="lamp"
                    supported-values="head;interior;fog-front;
                    fog-rear;brake;position-front;position-rear;
                    turn-left;turn-right;hazard"/>
           <request action="msg-static" int-id="3"/>
           <request action="msg-dynamic"/>
           <request action="honk"/>
           <request action="enable-camera"
                    supported-values="backup; interior"/>
           <request action="door-lock"/>
       </capabilities>

       </EmergencyCallData.Control>

                     Figure 9: <capabilities> Example



(page 21 continued on part 2)

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