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RFC 8147

 
 
 

Next-Generation Pan-European eCall

Part 2 of 2, p. 20 to 43
Prev Section

 


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10.  Examples

   Figure 6 illustrates an eCall.  The call uses the request URI
   urn:service:sos.ecall.automatic service URN and is recognized as an
   eCall, and further as one that was invoked automatically by the IVS
   due to a crash or other serious incident.  In this example, the
   originating network routes the call to an ESInet, which routes the
   call to the appropriate NG-eCall-capable PSAP.  The emergency call is
   received by the ESInet's Emergency Services Routing Proxy (ESRP), as
   the entry point into the ESInet.  The ESRP routes the call to a PSAP,
   where it is received by a call taker.  In deployments where there is
   no ESInet, the originating network routes the call directly to the
   appropriate NG-eCall-capable PSAP, an illustration of which would be
   identical to the one below except without an ESInet or ESRP.

               +-----------+  +----------------------------------------+
               |           |  |                  +-------+             |
               |           |  |                  | PSAP2 |             |
               |           |  |                  +-------+             |
               |           |  |                                        |
               |           |  |   +------+   +----------------------+  |
     Vehicle-->|           |--|-->| ESRP |-->| PSAP1 --> Call Taker |  |
               |           |  |   +------+   +----------------------+  |
               |           |  |                                        |
               |           |  |                  +-------+             |
               |           |  |                  | PSAP3 |             |
               |Originating|  |                  +-------+             |
               |  Mobile   |  |                                        |
               |  Network  |  |                ESInet                  |
               +-----------+  +----------------------------------------+

                Figure 6: Example of NG-eCall Message Flow

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   Figure 7 illustrates an eCall call flow with a mid-call PSAP request
   for an updated MSD.  The call flow shows the IVS initiating an
   emergency call, including the MSD in the INVITE.  The PSAP includes
   in the 200 OK response a metadata/control object acknowledging
   receipt of the MSD.  During the call, the PSAP sends a request for an
   MSD in an INFO request.  The IVS sends the requested MSD in a new
   INFO request.

            IVS                                         PSAP
             |(1) INVITE (eCall MSD)                      |
             |------------------------------------------->|
             |                                            |
             |(2) 200 OK (eCall metadata [ack MSD])       |
             |<-------------------------------------------|
             |                                            |
             |(3) start media stream(s)                   |
             |............................................|
             |                                            |
             |(4) INFO (eCall metadata [request MSD])     |
             |<-------------------------------------------|
             |                                            |
             |(5) 200 OK                                  |
             |------------------------------------------->|
             |                                            |
             |(6) INFO (eCall MSD)                        |
             |------------------------------------------->|
             |                                            |
             |(7) 200 OK                                  |
             |<-------------------------------------------|
             |                                            |
             |(8) BYE                                     |
             |<-------------------------------------------|
             |                                            |
             |(9) end media streams                       |
             |............................................|
             |                                            |
             |(10) 200 OK                                 |
             |------------------------------------------->|

                 Figure 7: NG-eCall Call Flow Illustration

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   Figure 8 illustrates a SIP eCall INVITE request containing an MSD.
   For simplicity, the example does not show all SIP headers, nor the
   Session Description Protocol (SDP) contents, nor does it show any
   additional data blocks added by the IVS or the originating mobile
   network.  Because the MSD is encoded in ASN.1 PER, which is a binary
   encoding, its contents cannot be included in a text document.

      INVITE urn:service:sos.ecall.automatic SIP/2.0
      To: urn:service:sos.ecall.automatic
      From: <sip:+13145551111@example.com>;tag=9fxced76sl
      Call-ID: 3848276298220188511@atlanta.example.com
      Geolocation: <cid:target123@example.com>
      Geolocation-Routing: no
      Call-Info: <cid:1234567890@atlanta.example.com>;
                 purpose=EmergencyCallData.eCall.MSD
      Accept: application/sdp, application/pidf+xml,
              application/EmergencyCallData.Control+xml
      CSeq: 31862 INVITE
      Recv-Info: EmergencyCallData.eCall.MSD
      Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
             SUBSCRIBE, NOTIFY, UPDATE
      Content-Type: multipart/mixed; boundary=boundary1
      Content-Length: ...

      --boundary1
      Content-Type: application/sdp

           ...Session Description Protocol (SDP) goes here...

      --boundary1
      Content-Type: application/pidf+xml
      Content-ID: <target123@example.com>
      Content-Disposition: by-reference;handling=optional

            ...PIDF-LO goes here...

      --boundary1
      Content-Type: application/EmergencyCallData.eCall.MSD
      Content-ID: <1234567890@atlanta.example.com>
      Content-Disposition: by-reference;handling=optional

           ...MSD in ASN.1 PER encoding goes here...

       --boundary1--

                       Figure 8: SIP NG-eCall INVITE

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   Continuing the example, Figure 9 illustrates a SIP 200 OK response to
   the INVITE request of Figure 8, containing a metadata/control block
   acknowledging successful receipt of the eCall MSD.  (For simplicity,
   the example does not show all SIP headers.)

      SIP/2.0 200 OK
      To: urn:service:sos.ecall.automatic;tag=8gydfe65t0
      From: <sip:+13145551111@example.com>;tag=9fxced76sl
      Call-ID: 3848276298220188511@atlanta.example.com
      Call-Info: <cid:2345678901@atlanta.example.com>;
                 purpose=EmergencyCallData.Control
      Accept: application/sdp, application/pidf+xml,
              application/EmergencyCallData.Control+xml,
              application/EmergencyCallData.eCall.MSD
      CSeq: 31862 INVITE
      Recv-Info: EmergencyCallData.eCall.MSD
      Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
             SUBSCRIBE, NOTIFY, UPDATE
      Content-Type: multipart/mixed; boundary=boundaryX
      Content-Length: ...

      --boundaryX
      Content-Type: application/sdp

           ...Session Description Protocol (SDP) goes here...

      --boundaryX
      Content-Type: application/EmergencyCallData.Control+xml
      Content-ID: <2345678901@atlanta.example.com>
      Content-Disposition: by-reference

      <?xml version="1.0" encoding="UTF-8"?>
      <EmergencyCallData.Control
          xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control">

      <ack received="true" ref="1234567890@atlanta.example.com"/>
      </EmergencyCallData.Control>

      --boundaryX--

                    Figure 9: 200 OK Response to INVITE

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   Figure 10 illustrates a SIP INFO request containing a metadata/
   control block requesting an eCall MSD.  (For simplicity, the example
   does not show all SIP headers.)

    INFO sip:+13145551111@example.com SIP/2.0
    To: <sip:+13145551111@example.com>;tag=9fxced76sl
    From: Exemplar PSAP <urn:service:sos.ecall.automatic>;tag=8gydfe65t0
    Call-ID: 3848276298220188511@atlanta.example.com
    Call-Info: <cid:3456789012@atlanta.example.com>;
               purpose=EmergencyCallData.Control
    CSeq: 41862 INFO
    Info-Package: EmergencyCallData.eCall.MSD
    Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
           SUBSCRIBE, NOTIFY, UPDATE
    Content-Type: multipart/mixed; boundary=boundaryZZZ
    Content-Disposition: Info-Package
    Content-Length: ...

    --boundaryZZZ
    Content-Disposition: by-reference
    Content-Type: application/EmergencyCallData.Control+xml
    Content-ID: <3456789012@atlanta.example.com>

    <?xml version="1.0" encoding="UTF-8"?>
    <EmergencyCallData.Control
        xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control">

    <request action="send-data" datatype="eCall.MSD"/>

    </EmergencyCallData.Control>
     --boundaryZZZ--

                      Figure 10: INFO Requesting MSD

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   Figure 11 illustrates a SIP INFO request containing an MSD.  For
   simplicity, the example does not show all SIP headers.  Because the
   MSD is encoded in ASN.1 PER, which is a binary encoding, its contents
   cannot be included in a text document.

      INFO urn:service:sos.ecall.automatic SIP/2.0
      To: urn:service:sos.ecall.automatic;tag=8gydfe65t0
      From: <sip:+13145551111@example.com>;tag=9fxced76sl
      Call-ID: 3848276298220188511@atlanta.example.com
      Call-Info: <cid:4567890123@atlanta.example.com>;
                 purpose=EmergencyCallData.eCall.MSD
      CSeq: 51862 INFO
      Info-Package: EmergencyCallData.eCall.MSD
      Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
             SUBSCRIBE, NOTIFY, UPDATE
      Content-Type: multipart/mixed; boundary=boundaryLine
      Content-Disposition: Info-Package
      Content-Length: ...

      --boundaryLine
      Content-Type: application/EmergencyCallData.eCall.MSD
      Content-ID: <4567890123@atlanta.example.com>
      Content-Disposition: by-reference

           ...MSD in ASN.1 PER encoding goes here...

      --boundaryLine--

                      Figure 11: INFO Containing MSD

11.  Security Considerations

   The security considerations described in [RFC5069] (on marking and
   routing emergency calls) apply here.

   In addition to any network-provided location (which might be
   determined solely by the network or in cooperation with or possibly
   entirely by the originating device), an eCall carries an IVS-supplied
   location within the MSD.  This is likely to be useful to the PSAP,
   especially when no network-provided location is included, or when the
   two locations are independently determined.  Even in situations where
   the network-supplied location is limited to the cell site, this can
   be useful as a sanity check on the device-supplied location contained
   in the MSD.

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   The document [RFC7378] discusses trust issues regarding location
   provided by or determined in cooperation with end devices.

   Security considerations specific to the mechanism by which the PSAP
   sends acknowledgments and requests to the vehicle are discussed in
   the "Security Considerations" block of Section 14.4.  Note that an
   attacker that has access to and is capable of generating a response
   to the initial INVITE request could generate a 600 (Busy Everywhere),
   486 (Busy Here), or 603 (Decline) response that includes a metadata/
   control object containing a reference to the MSD in the initial
   INVITE and a "received=true" field, which could result in the IVS
   perceiving the PSAP to be overloaded and hence not attempting to
   reinitiate the call.  The risk can be mitigated as discussed in the
   "Security Considerations" block of Section 14.4.

   Data received from external sources inherently carries implementation
   risks.  For example, depending on the platform, buffer overflows can
   introduce remote code execution vulnerabilities, null characters can
   corrupt strings, numeric values used for internal calculations can
   result in underflow/overflow errors, malformed XML objects can expose
   parsing bugs, etc.  Implementations need to be cognizant of the
   potential risks, observe best practices (which might include
   sufficiently capable static code analysis, fuzz testing, component
   isolation, avoiding use of unsafe coding techniques, third-party
   attack tests, signed software, over-the-air updates, etc.), and have
   multiple levels of protection.  Implementors need to be aware that,
   potentially, the data objects described here and elsewhere (including
   the MSD and metadata/control objects) might be malformed, contain
   unexpected characters, have excessively long attribute values and
   elements, etc.

   The security considerations discussed in [RFC7852] apply here (see
   especially the discussion of Transport Layer Security (TLS), TLS
   versions, cipher suites, and PKI).

   When vehicle data or control/metadata is contained in a signed or
   encrypted body part, the enclosing multipart (e.g., multipart/signed
   or multipart/encrypted) has the same Content-ID as the enclosed data
   part.  This allows an entity to identify and access the data blocks
   it is interested in without having to dive deeply into the message
   structure or decrypt parts it is not interested in.  (The "purpose"
   parameter in a Call-Info header field identifies the data and
   contains a CID URL pointing to the data block in the body, which has
   a matching Content-ID body part header field.)

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12.  Privacy Considerations

   The privacy considerations discussed in [RFC7852] apply here.  The
   MSD carries some identifying and personal information (mostly about
   the vehicle and less about the owner), as well as location
   information, so it needs to be protected against unauthorized
   disclosure.  Local regulations may impose additional privacy
   protection requirements.

   Privacy considerations specific to the data structure containing
   vehicle information are discussed in the "Security Considerations"
   block of Section 14.3.

   Privacy considerations specific to the mechanism by which the PSAP
   sends acknowledgments and requests to the vehicle are discussed in
   the "Security Considerations" block of Section 14.4.

13.  XML Schema

   This section defines an XML schema for the control block.  The text
   description of the control block in Section 9.1 is normative and
   supersedes any conflicting aspect of this schema.

    <?xml version="1.0"?>
    <xs:schema
      targetNamespace="urn:ietf:params:xml:ns:EmergencyCallData:control"
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:pi="urn:ietf:params:xml:ns:EmergencyCallData:control"
      xmlns:xml="http://www.w3.org/XML/1998/namespace"
      elementFormDefault="qualified"
      attributeFormDefault="unqualified">

        <xs:import namespace="http://www.w3.org/XML/1998/namespace"/>

        <xs:element name="EmergencyCallData.Control"
                    type="pi:controlType"/>

        <xs:complexType name="controlType">
           <xs:complexContent>
              <xs:restriction base="xs:anyType">
                 <xs:choice>
                    <xs:element name="capabilities"
                                type="pi:capabilitiesType"/>
                    <xs:element name="request" type="pi:requestType"/>
                    <xs:element name="ack" type="pi:ackType"/>

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                    <xs:any namespace="##any" processContents="lax"
                            minOccurs="0"
                            maxOccurs="unbounded"/>
                 </xs:choice>
                 <xs:anyAttribute/>
              </xs:restriction>
           </xs:complexContent>
        </xs:complexType>

        <xs:complexType name="ackType">
            <xs:complexContent>
                <xs:restriction base="xs:anyType">
                    <xs:sequence minOccurs="1" maxOccurs="unbounded">
                        <xs:element name="actionResult" minOccurs="0"
                                    maxOccurs="unbounded">
                            <xs:complexType>
                                <xs:attribute name="action"
                                              type="xs:token"
                                              use="required"/>
                                <xs:attribute name="success"
                                              type="xs:boolean"
                                              use="required"/>
                                <xs:attribute name="reason"
                                              type="xs:token">
                                    <xs:annotation>
                                        <xs:documentation>
                                            conditionally mandatory
                                            when @success="false"
                                            to indicate reason code
                                            for a failure
                                        </xs:documentation>
                                    </xs:annotation>
                                </xs:attribute>
                                <xs:attribute name="details"
                                              type="xs:string"/>
                                <xs:anyAttribute
                                    processContents="skip"/>
                            </xs:complexType>
                        </xs:element>
                        <xs:any namespace="##any" processContents="lax"
                                minOccurs="0"
                                maxOccurs="unbounded"/>
                    </xs:sequence>
                    <xs:attribute name="ref"
                                  type="xs:anyURI"
                                  use="required"/>

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                    <xs:attribute name="received"
                                  type="xs:boolean"/>
                    <xs:anyAttribute/>
                </xs:restriction>
            </xs:complexContent>
        </xs:complexType>

        <xs:complexType name="capabilitiesType">
            <xs:complexContent>
                <xs:restriction base="xs:anyType">
                    <xs:sequence minOccurs="1" maxOccurs="unbounded">
                        <xs:element name="request"
                                    type="pi:requestType"
                                    minOccurs="1"
                            maxOccurs="unbounded"/>
                        <xs:any namespace="##any" processContents="lax"
                                 minOccurs="0"
                            maxOccurs="unbounded"/>
                    </xs:sequence>
                    <xs:anyAttribute/>
                </xs:restriction>
            </xs:complexContent>
        </xs:complexType>

        <xs:complexType name="requestType">
           <xs:complexContent>
                <xs:restriction base="xs:anyType">
                    <xs:choice minOccurs="1" maxOccurs="unbounded">
                        <xs:element name="text" minOccurs="0"
                                    maxOccurs="unbounded">
                            <xs:complexType>
                                <xs:simpleContent>
                                    <xs:extension base="xs:string">
                                        <xs:anyAttribute
                                            namespace="##any"
                                            processContents="skip"/>
                                    </xs:extension>
                                </xs:simpleContent>
                            </xs:complexType>
                        </xs:element>
                        <xs:any namespace="##any" processContents="lax"
                                minOccurs="0"
                                maxOccurs="unbounded"/>
                    </xs:choice>
                    <xs:attribute name="action" type="xs:token"
                                  use="required"/>

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                    <xs:attribute name="int-id" type="xs:unsignedInt"/>
                    <xs:attribute name="persistence"
                                  type="xs:duration"/>
                    <xs:attribute name="datatype" type="xs:token"/>
                    <xs:attribute name="supported-values"
                                  type="xs:string"/>
                    <xs:attribute name="element-id" type="xs:token"/>
                    <xs:attribute name="requested-state"
                                  type="xs:token"/>
                    <xs:anyAttribute/>
                </xs:restriction>
            </xs:complexContent>
        </xs:complexType>

    </xs:schema>

                      Figure 12: Control Block Schema

14.  IANA Considerations

14.1.  The EmergencyCallData Media Subtree

   This document establishes the "EmergencyCallData" media (MIME)
   subtype tree, a new media subtree rooted at "application/
   EmergencyCallData".  This subtree is used only for content associated
   with emergency communications.  New subtypes in this subtree follow
   the rules specified in Section 3.1 of [RFC6838], with the additional
   restriction that the standards-related organization MUST be
   responsible for some aspect of emergency communications.

   This subtree initially contains the following subtypes (defined here
   or in [RFC7852]):

      EmergencyCallData.Comment+xml
      EmergencyCallData.Control+xml
      EmergencyCallData.DeviceInfo+xml
      EmergencyCallData.eCall.MSD
      EmergencyCallData.ProviderInfo+xml
      EmergencyCallData.ServiceInfo+xml
      EmergencyCallData.SubscriberInfo+xml

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14.2.  Service URN Registrations

   IANA has registered the URN urn:service:sos.ecall under the "'sos'
   Sub-Services" registry defined in Section 4.2 of [RFC5031].

   This service requests resources associated with an emergency call
   placed by an in-vehicle system, carrying a standardized set of data
   related to the vehicle and incident.  The "Description" registry
   field is "Vehicle-initiated emergency calls".  Two sub-services are
   registered as well:

   urn:service:sos.ecall.automatic

      Used with an eCall invoked automatically, for example, due to a
      crash or other serious incident.  The "Description" registry field
      is "Automatic vehicle-initiated emergency calls".

   urn:service:sos.ecall.manual

      Used with an eCall invoked due to manual interaction by a vehicle
      occupant.  The "Description" registry field is "Manual vehicle-
      initiated emergency calls".

   IANA has also registered the URN urn:service:test.sos.ecall under the
   "'test' Sub-Services" registry defined in Section 17.2 of [RFC6881].
   This service requests resources associated with a test (non-
   emergency) call placed by an in-vehicle system.  See Section 8 for
   more information on the test eCall request URN.

14.3.  MIME Media Type Registration for application/
       EmergencyCallData.eCall.MSD

   IANA has added application/EmergencyCallData.eCall.MSD as a MIME
   media type, with a reference to this document, in accordance with the
   procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303
   [RFC7303].

      MIME media type name:  application

      MIME subtype name:  EmergencyCallData.eCall.MSD

      Mandatory parameters:  none

      Optional parameters:  none

      Encoding scheme:  binary

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      Encoding considerations:
         Uses ASN.1 PER, which is a binary encoding; when transported in
         SIP, binary content transfer encoding is used.

      Security considerations:
         This media type is designed to carry vehicle and incident-
         related data during an emergency call.  This data contains
         personal information including vehicle VIN, location,
         direction, etc.  Appropriate precautions need to be taken to
         limit unauthorized access, inappropriate disclosure to third
         parties, and eavesdropping of this information.  Sections 9 and
         10 of [RFC7852] contain more discussion.

      Interoperability considerations:   None

      Published specification:   Annex A of EN 15722 [MSD]

      Applications which use this media type:
         Pan-European eCall compliant systems

      Additional information:   None

      Magic Number:   None

      File Extension:   None

      Macintosh file type code:   BINA

      Person and email address for further information:
         Randall Gellens, rg+ietf@randy.pensive.org

      Intended usage:   LIMITED USE

      Author:   The MSD specification was produced by the European
         Committee For Standardization (CEN).  For contact information,
         please see <http://www.cen.eu/cen/Pages/contactus.aspx>.

      Change controller:   The European Committee For Standardization
         (CEN)

14.4.  MIME Media Type Registration for application/
       EmergencyCallData.Control+xml

   IANA has added application/EmergencyCallData.Control+xml as a MIME
   media type, with a reference to this document, in accordance to the
   procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303
   [RFC7303].

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      MIME media type name:  application

      MIME subtype name:  EmergencyCallData.Control+xml

      Mandatory parameters:  none

      Optional parameters:  charset

         Indicates the character encoding of the XML content.

      Encoding considerations:
         Uses XML, which can employ 8-bit characters, depending on the
         character encoding used.  See Section 3.2 of RFC 7303
         [RFC7303].

      Security considerations:
         This media type carries metadata and control information and
         requests, such as from a Public Safety Answering Point (PSAP)
         to an In-Vehicle System (IVS) during an emergency call.

         Metadata (such as an acknowledgment that data sent by the IVS
         to the PSAP was successfully received) has limited privacy and
         security implications.  Control information (such as requests
         from the PSAP that the vehicle perform an action) has some
         privacy and security implications.  The privacy concern arises
         from the ability to request the vehicle to transmit a data set,
         which as described in Section 14.3 can contain personal
         information.  The security concern is the ability to request
         the vehicle to perform an action.  Control information needs to
         originate only from a PSAP or other emergency services
         providers and not be modified en route.  The level of integrity
         of the cellular network over which the emergency call is placed
         is a consideration: when the IVS initiates an eCall over a
         cellular network, in most cases it relies on the MNO to route
         the call to a PSAP.  (Calls placed using other means, such as
         Wi-Fi or over-the-top services, generally incur somewhat higher
         levels of risk than calls placed "natively" using cellular
         networks.)  A callback from a PSAP merits additional
         consideration, since current mechanisms are not ideal for
         verifying that such a call is indeed a callback from a PSAP in
         response to an emergency call placed by the IVS.  See the
         discussion in Section 11 and the PSAP Callback document
         [RFC7090].

         Sections 7 and 8 of [RFC7852] contain more discussion.

      Interoperability considerations:   None

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      Published specification:   This document

      Applications which use this media type:
         Pan-European eCall compliant systems

      Additional information:   None

      Magic Number:   None

      File Extension:   .xml

      Macintosh file type code:   TEXT

      Person and email address for further information:
         Randall Gellens, rg+ietf@randy.pensive.org

      Intended usage:   LIMITED USE

      Author:   The IETF ECRIT working group

      Change controller:   The IETF ECRIT working group

14.5.  Registration of the "eCall.MSD" Entry in the Emergency Call Data
       Types Registry

   IANA has added the "eCall.MSD" entry to the "Emergency Call Data
   Types" registry, with a reference to this document; the "Data About"
   value is "The Call".

14.6.  Registration of the "Control" Entry in the Emergency Call Data
       Types Registry

   IANA has added the "Control" entry to the "Emergency Call Data Types"
   registry, with a reference to this document; the "Data About" value
   is "The Call".

14.7.  Registration for urn:ietf:params:xml:ns:EmergencyCallData:control

   This section registers a new XML namespace, as per the guidelines in
   RFC 3688 [RFC3688].

   URI:  urn:ietf:params:xml:ns:EmergencyCallData:control

   Registrant Contact:  IETF, ECRIT working group, <ecrit@ietf.org>, as
      delegated by the IESG <iesg@ietf.org>.

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   XML:

     BEGIN
     <?xml version="1.0"?>
     <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
          "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
     <html xmlns="http://www.w3.org/1999/xhtml">
     <head>
          <meta http-equiv="content-type"
                content="text/html;charset=iso-8859-1"/>
          <title>Namespace for Emergency Call Data Control Block</title>
     </head>
     <body>
          <h1>Namespace for Emergency Call Data Control Block</h1>
     <p>See RFC 8147</p>
     </body>
     </html>
     END

14.8.  Registry Creation

   This document creates a new registry called "Emergency Call Metadata/
   Control Data".  The following sub-registries are created for this
   registry.

14.8.1.  Emergency Call Actions Registry

   This document creates a new sub-registry called "Emergency Call
   Actions".  As defined in [RFC5226], this registry operates under
   "Expert Review" rules.  The expert should determine that the proposed
   action is within the purview of a vehicle, is sufficiently
   distinguishable from other actions, and is clearly and fully
   described.  In most cases, a published and stable document is
   referenced for the description of the action.

   The content of this registry includes:

   Name:  The identifier to be used in the "action" attribute of a
      control <request> element.

   Description:  A description of the action.  In most cases, this will
      be a reference to a published and stable document.  The
      description MUST specify if any attributes or child elements are
      optional or mandatory and describe the action to be taken by the
      vehicle.

   The initial set of values is listed in Table 1.

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           +-----------+--------------------------------------+
           |    Name   |             Description              |
           +-----------+--------------------------------------+
           | send-data | See Section 9.1.3.1 of this document |
           +-----------+--------------------------------------+

          Table 1: Emergency Call Actions Registry Initial Values

14.8.2.  Emergency Call Action Failure Reasons Registry

   This document creates a new sub-registry called "Emergency Call
   Action Failure Reasons", which contains values for the "reason"
   attribute of the <actionResult> element.  As defined in [RFC5226],
   this registry operates under "Expert Review" rules.  The expert
   should determine that the proposed reason is sufficiently
   distinguishable from other reasons and that the proposed description
   is understandable and correctly worded.

   The content of this registry includes:

   ID:  A short string identifying the reason, for use in the "reason"
      attribute of an <actionResult> element.

   Description:  A description of the reason.

   The initial set of values is listed in Table 2.

   +------------------+------------------------------------------------+
   | ID               | Description                                    |
   +------------------+------------------------------------------------+
   | damaged          | Required components are damaged.               |
   |                  |                                                |
   | data-unsupported | The data item referenced in a "send-data"      |
   |                  | request is not supported.                      |
   |                  |                                                |
   | security-failure | The authenticity of the request or the         |
   |                  | authority of the requestor could not be        |
   |                  | verified.                                      |
   |                  |                                                |
   | unable           | The action could not be accomplished (a        |
   |                  | generic error for use when no other code is    |
   |                  | appropriate).                                  |
   |                  |                                                |
   | unsupported      | The "action" value is not supported.           |
   +------------------+------------------------------------------------+

      Table 2: Emergency Call Action Failure Reasons Registry Initial
                                  Values

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14.9.  The EmergencyCallData.eCall.MSD INFO Package

   This document registers the EmergencyCallData.eCall.MSD INFO package
   in the "Info Packages Registry".

   Both endpoints (the IVS and the PSAP equipment) include
   EmergencyCallData.eCall.MSD in a Recv-Info header field per [RFC6086]
   to indicate the ability to receive INFO requests carrying data as
   described here.

   Support for the EmergencyCallData.eCall.MSD INFO package indicates
   the ability to receive eCall related body parts as specified in this
   document.

   An INFO request message carrying body parts related to an emergency
   call as described in this document has an Info-Package header field
   set to "EmergencyCallData.eCall.MSD" per [RFC6086].

   The requirements of Section 10 of [RFC6086] are addressed in the
   following sections.

14.9.1.  Overall Description

   This section describes what type of information is carried in INFO
   requests associated with the INFO package and for what types of
   applications and functionalities User Agents (UAs) can use the INFO
   package.

   INFO requests associated with the EmergencyCallData.eCall.MSD INFO
   package carry data associated with emergency calls as defined in this
   document.  The application is vehicle-initiated emergency calls
   established using SIP.  The functionality is to carry vehicle data
   and metadata/control information between vehicles and PSAPs.

14.9.2.  Applicability

   This section describes why the INFO package mechanism, rather than
   some other mechanism, has been chosen for the specific use case.

   The use of the SIP INFO method is based on an analysis of the
   requirements against the intent and effects of the INFO method versus
   other approaches (which included the SIP MESSAGE method, the SIP
   OPTIONS method, the SIP re-INVITE method, media-plane transport, and
   non-SIP protocols).  In particular, the transport of emergency call
   data blocks occurs within a SIP emergency dialog, per Section 6, and
   is normally carried in the initial INVITE request and response; the
   use of the SIP INFO method only occurs when emergency-call-related
   data needs to be sent mid call.  While the SIP MESSAGE method could

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   be used, it is not tied to a SIP dialog as is the SIP INFO method and
   thus might not be associated with the dialog.  Either SIP OPTIONS or
   re-INVITE methods could also be used, but they are seen as less clean
   than the SIP INFO method.  The SIP SUBSCRIBE/NOTIFY method could be
   coerced into service, but the semantics are not a good fit, e.g., the
   subscribe/notify mechanism provides one-way communication consisting
   of (often multiple) notifications from notifier to subscriber
   indicating that certain events in notifier have occurred, whereas
   what's needed here is two-way communication of data related to the
   emergency dialog.  Use of media-plane mechanisms was discounted
   because the number of messages needing to be exchanged in a dialog is
   normally zero or very few, and the size of the data is likewise very
   small.  The overhead caused by user-plane setup (e.g., to use the
   Message Session Relay Protocol (MSRP) as transport) would be
   disproportionately large.

   Based on the analyses, the SIP INFO method was chosen to provide for
   mid-call data transport.

14.9.3.  INFO Package Name

   The INFO package name is EmergencyCallData.eCall.MSD

14.9.4.  INFO Package Parameters

   None

14.9.5.  SIP Option-Tags

   None

14.9.6.  INFO Request Body Parts

   The body for an EmergencyCallData.eCall.MSD INFO package is a
   multipart (normally multipart/mixed) body containing zero or one
   application/EmergencyCallData.eCall.MSD parts (containing an MSD) and
   zero or more application/EmergencyCallData.Control+xml (containing a
   metadata/control object) parts.  At least one MSD or metadata/control
   body part is expected; the behavior upon receiving an INFO request
   with neither is undefined.

   The body parts are sent per [RFC6086], and in addition, to align with
   how these body parts are sent in SIP messages other than INFO
   requests, each associated body part is referenced by a Call-Info
   header field at the top level of the SIP message.  The body part has
   a Content-Disposition header field set to "By-Reference".

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   An MSD or metadata/control block is always enclosed in a multipart
   body part (even if it would otherwise be the only body part in the
   SIP message).  The outermost multipart that contains only body parts
   associated with the INFO package has a Content-Disposition value of
   "Info-Package".

14.9.7.  INFO Package Usage Restrictions

   Usage is limited to vehicle-initiated emergency calls as defined in
   this document.

14.9.8.  Rate of INFO Requests

   The SIP INFO request is used within an established emergency call
   dialog for the PSAP to request the IVS to send an updated MSD and for
   the IVS to send a requested MSD.  Because this is normally done only
   on manual request of the PSAP call taker (who suspects some aspect of
   the vehicle state has changed), the rate of SIP INFO requests
   associated with the EmergencyCallData.eCall.MSD INFO package is
   normally quite low (most dialogs are likely to contain zero INFO
   requests, while others might carry an occasional request).

14.9.9.  INFO Package Security Considerations

   The MIME media type registrations specified for use with this INFO
   package (Sections 14.3 and 14.4) contain a discussion of the security
   and/or privacy considerations specific to that data block.  See
   Sections 11 and 12 for a discussion of the security and privacy
   considerations of the data carried in eCalls.

14.9.10.  Implementation Details

   See Sections 6 and 7 for protocol details.

14.9.11.  Examples

   See Section 10 for protocol examples.

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15.  References

15.1.  Normative References

   [MSD]      European Committee for Standardization, "Intelligent
              transport systems - eSafety - eCall minimum set of data
              (MSD)", Standard: CEN - EN 15722, April 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <http://www.rfc-editor.org/info/rfc3688>.

   [RFC5031]  Schulzrinne, H., "A Uniform Resource Name (URN) for
              Emergency and Other Well-Known Services", RFC 5031,
              DOI 10.17487/RFC5031, January 2008,
              <http://www.rfc-editor.org/info/rfc5031>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC6086]  Holmberg, C., Burger, E., and H. Kaplan, "Session
              Initiation Protocol (SIP) INFO Method and Package
              Framework", RFC 6086, DOI 10.17487/RFC6086, January 2011,
              <http://www.rfc-editor.org/info/rfc6086>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <http://www.rfc-editor.org/info/rfc6838>.

   [RFC6881]  Rosen, B. and J. Polk, "Best Current Practice for
              Communications Services in Support of Emergency Calling",
              BCP 181, RFC 6881, DOI 10.17487/RFC6881, March 2013,
              <http://www.rfc-editor.org/info/rfc6881>.

   [RFC7303]  Thompson, H. and C. Lilley, "XML Media Types", RFC 7303,
              DOI 10.17487/RFC7303, July 2014,
              <http://www.rfc-editor.org/info/rfc7303>.

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   [RFC7852]  Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and
              J. Winterbottom, "Additional Data Related to an Emergency
              Call", RFC 7852, DOI 10.17487/RFC7852, July 2016,
              <http://www.rfc-editor.org/info/rfc7852>.

15.2.  Informative references

   [CEN]      "European Committee for Standardization (CEN)",
              <http://www.cen.eu>.

   [EN_16062] European Committee for Standardization, "Intelligent
              transport systems - eSafety - eCall High Level Application
              Requirements (HLAP) Using GSM/UMTS Circuit Switched
              Networks", Standard: CEN - EN 16062, April 2015.

   [EN_16072] European Committee for Standardization, "Intelligent
              transport systems - eSafety - Pan-European eCall operating
              requirements", Standard: CEN - EN 16072, April 2015.

   [MSG_TR]   ETSI, "Mobile Standards Group (MSG); eCall for VoIP",
              ETSI TR 103 140 V1.1.1, April 2014.

   [RFC5012]  Schulzrinne, H. and R. Marshall, Ed., "Requirements for
              Emergency Context Resolution with Internet Technologies",
              RFC 5012, DOI 10.17487/RFC5012, January 2008,
              <http://www.rfc-editor.org/info/rfc5012>.

   [RFC5069]  Taylor, T., Ed., Tschofenig, H., Schulzrinne, H., and M.
              Shanmugam, "Security Threats and Requirements for
              Emergency Call Marking and Mapping", RFC 5069,
              DOI 10.17487/RFC5069, January 2008,
              <http://www.rfc-editor.org/info/rfc5069>.

   [RFC6443]  Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
              "Framework for Emergency Calling Using Internet
              Multimedia", RFC 6443, DOI 10.17487/RFC6443, December
              2011, <http://www.rfc-editor.org/info/rfc6443>.

   [RFC7090]  Schulzrinne, H., Tschofenig, H., Holmberg, C., and M.
              Patel, "Public Safety Answering Point (PSAP) Callback",
              RFC 7090, DOI 10.17487/RFC7090, April 2014,
              <http://www.rfc-editor.org/info/rfc7090>.

   [RFC7378]  Tschofenig, H., Schulzrinne, H., and B. Aboba, Ed.,
              "Trustworthy Location", RFC 7378, DOI 10.17487/RFC7378,
              December 2014, <http://www.rfc-editor.org/info/rfc7378>.

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   [RFC8148]  Gellens, R., Rosen, B., and H. Tschofenig, "Next-
              Generation Vehicle-Initiated Emergency Calls", RFC 8148,
              DOI 10.17487/RFC8148, May 2017,
              <http://www.rfc-editor.org/info/rfc8148>.

   [SDO-3GPP] "3rd Generation Partnership Project (3GPP)",
              <http://www.3gpp.org/>.

   [SDO-ETSI] "European Telecommunications Standards Institute (ETSI)",
              <http://www.etsi.org>.

   [TS22.101] 3GPP, "Universal Mobile Telecommunications System (UMTS);
              Service aspects; Service principles", 3GPP TS
              22.101, version 8.7.0, Release 8, January 2008.

   [TS23.167] 3GPP, "IP Multimedia Subsystem (IMS) emergency sessions",
              3GPP TS 23.167, version 9.6.0, Release 9, March 2011.

   [TS24.229] 3GPP, "IP multimedia call control protocol based on
              Session Initiation Protocol (SIP) and Session Description
              Protocol (SDP); Stage 3", 3GPP TS 24.229, version 12.6.0,
              Release 12, October 2014.

Acknowledgments

   We would like to thank Bob Williams and Ban Al-Bakri for their
   feedback and suggestions; Rex Buddenberg, Lena Chaponniere, Alissa
   Cooper, Keith Drage, Stephen Edge, Wes George, Mirja Kuehlewind,
   Allison Mankin, Alexey Melnikov, Ivo Sedlacek, and James Winterbottom
   for their review and comments; Robert Sparks and Paul Kyzivat for
   their help with the SIP mechanisms; and Mark Baker and Ned Freed for
   their help with the media subtype registration issue.  We would like
   to thank Michael Montag, Arnoud van Wijk, Gunnar Hellstrom, and
   Ulrich Dietz for their help with the original document upon which
   this document is based.  Christer Holmberg deserves special mention
   for his many detailed reviews.

Contributors

   Brian Rosen was a co-author of the original document upon which this
   document is based.

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Authors' Addresses

   Randall Gellens
   Core Technology Consulting

   Email: rg+ietf@coretechnologyconsulting.com
   URI:   http://www.coretechnologyconsulting.com


   Hannes Tschofenig
   Individual

   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at