ECRIT R. Gellens
Internet-Draft Consultant
Intended status: Standards Track H. Tschofenig
Expires: January 2, 2017 Individual
July 1, 2016

Next-Generation Pan-European eCall
draft-ietf-ecrit-ecall-08.txt

Abstract

This document describes how to use IP-based emergency services mechanisms to support the next generation of the Pan European in-vehicle emergency call service defined under the eSafety initiative of the European Commission (generally referred to as "eCall"). eCall is a standardized and mandated system for a special form of emergency calls placed by vehicles, providing real-time communications and an integrated set of related data.

This document also registers a MIME Content Type and an Emergency Call Additional Data Block for the eCall vehicle data and metadata/control data.

Status of This Memo

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

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

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This Internet-Draft will expire on January 2, 2017.

Copyright Notice

Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1. 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].

This document re-uses terminology defined in Section 3 of [RFC5012].

Additionally, we use the following abbreviations:

Term Expansion
3GPP 3rd Generation Partnership Project
CEN European Committee for Standardization
EENA European Emergency Number Association
ESInet Emergency Services IP network
IMS IP Multimedia Subsystem
IVS In-Vehicle System
MNO Mobile Network Operator
MSD Minimum Set of Data
PSAP Public Safety Answering Point

2. Document Scope

This document is limited to the signaling, data exchange, and protocol needs of next-generation eCall (NG-eCall, also referred to as packet-switched eCall (PS-eCall) and all-IP eCall) within the SIP framework for emergency calls, as described in [RFC6443] and [RFC6881]. eCall itself is specified by 3GPP and CEN and these specifications include far greater scope than is covered here.

The eCall service operates over cellular wireless communication, but this document does not address cellular-specific details, nor client domain selection (e.g., circuit-switched versus packet-switched). All such aspects are the purview of their respective standards bodies. The scope of this document is limited to eCall operating within a SIP-based environment (e.g., 3GPP IMS Emergency Calling).

The technical contents of this document can be suitable for use in other vehicle-initiated emergency call systems, but this is out of scope for this document.

Vehicles designed for multiple regions might need to support eCall and other Advanced Automatic Crash Notification (AACN) systems, such as described in [I-D.ietf-ecrit-car-crash]. That system is compatible with eCall, differing primarily in the specific data set that is sent.

3. Introduction

Emergency calls made from vehicles (e.g., in the event of a crash) assist in significantly reducing road deaths and injuries by allowing emergency services to be aware of the incident, the state of the vehicle, the location of the vehicle, and to have a voice channel with the vehicle occupants. This enables a quick and appropriate response.

The European Commission initiative of eCall was conceived in the late 1990s, and has evolved to a European Parliament decision requiring the implementation of a compliant in-vehicle system (IVS) in new vehicles and the deployment of eCall in the European Member States in the very near future. Other regions are developing eCall-compatible systems.

The pan-European eCall system provides a standardized and mandated mechanism for emergency calls by vehicles. eCall establishes procedures for such calls to be placed by in-vehicle systems, recognized and processed by the mobile network, and routed to a specialized PSAP where the vehicle data is available to assist the call taker in assessing and responding to the situation. eCall provides a standard set of vehicle, sensor (e.g., crash related), and location data.

An eCall can be either user-initiated or automatically triggered. Automatically triggered eCalls indicate a car crash or some other serious incident. Manually triggered eCalls might be reports of witnessed crashes or serious hazards. PSAPs might apply specific operational handling to manual and automatic eCalls.

Legacy eCall is standardized (by 3GPP [SDO-3GPP] and CEN [CEN]) as a 3GPP circuit-switched call over GSM (2G) or UMTS (3G). Flags in the call setup mark the call as an eCall, and further indicate if the call was automatically or manually triggered. The call is routed to an eCall-capable PSAP, a voice channel is established between the vehicle and the PSAP, and an eCall in-band modem is used to carry a defined set of vehicle, sensor (e.g., crash related), and location data (the Minimum Set of Data or MSD) within the voice channel. The same in-band mechanism is used for the PSAP to acknowledge successful receipt of the MSD, and to request the vehicle to send a new MSD (e.g., to check if the state of or location of the vehicle or its occupants has changed). NG-eCall moves from circuit switched to all-IP, and carries the vehicle data and other eCall-specific data as additional data carried with the call. This document describes how IETF mechanisms for IP-based emergency calls, including [RFC6443] and [I-D.ietf-ecrit-additional-data] are used to provide the signaling and data exchange of the next generation of pan-European eCall.

The European Telecommunications Standards Institute (ETSI) [SDO-ETSI] has published a Technical Report titled "Mobile Standards Group (MSG); eCall for VoIP" [MSG_TR] that presents findings and recommendations regarding support for eCall in an all-IP environment. The recommendations include the use of 3GPP IMS emergency calling with additional elements identifying the call as an eCall and as carrying eCall data and with mechanisms for carrying the data and eCall-specific signaling. 3GPP IMS emergency services support multimedia, providing the ability to carry voice, text, and video. This capability is referred to within 3GPP as Multimedia Emergency Services (MMES).

A transition period will exist during which time the various entities involved in initiating and handling an eCall might support next-generation eCall, legacy eCall, or both. The issues of migration and co-existence during the transition period is outside the scope of this document.

4. eCall Requirements

eCall requirements are specified by CEN in [EN_16072] and by 3GPP in [TS22.101] clauses 10.7 and A.27. Requirements specific to vehicle data are contained in EN 15722 [msd].

5. Vehicle Data

Pan-European eCall provides a standardized and mandated set of vehicle related data, known as the Minimum Set of Data (MSD). The European Committee for Standardization (CEN) has specified this data in EN 15722 [msd], along with both ASN.1 and XML encodings for the MSD [msd]. Both circuit-switched eCall and this document use the ASN.1 PER encoding, which is specified in Annex A of EN 15722 [msd] (the XML encoding specified in Annex C is not used in this document).

The "Additional Data related to an Emergency Call" document [I-D.ietf-ecrit-additional-data] establishes a general mechanism for attaching blocks of data to a SIP emergency call. This document makes use of that mechanism to carry the eCall MSD in a SIP emergency call.

This document registers the 'application/emergencyCallData.eCall.MSD+per' MIME Content-Type to enable the MSD to be carried in SIP. As an ASN.1 PER encoded object, the data is binary and transported using binary content transfer encoding within SIP messages. This document also adds the 'eCall.MSD' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]) to enable the MSD to be recognized as such in a SIP-based eCall emergency call.

Note that if additional data sets are defined and registered (e.g., in the future or in other regions) and transmitted using the same mechanisms, the size and frequency of transmission during a dialog need to be evaluated to be sure it is appropriate to use the signaling channel.

6. Call Setup

In circuit-switched eCall, the IVS places a special form of a 112 emergency call which carries an eCall flag (indicating that the call is an eCall and also if the call was manually or automatically triggered); the mobile network operator (MNO) recognizes the eCall flag and routes the call to an eCall-capable PSAP; vehicle data is transmitted to the PSAP via the eCall in-band modem (in the voice channel).

   ///----\\\      112 voice call with eCall flag      +------+
  ||| IVS  |||---------------------------------------->+ PSAP |
   \\\----///   vehicle data via eCall in-band modem   +------+

Figure 1: circuit-switched eCall

An In-Vehicle System (IVS) initiating an NG-eCall transmits the MSD in accordance with [I-D.ietf-ecrit-additional-data] by encoding it as specified (per Annex A of EN 15722 [msd]) and attaching it to an INVITE as a MIME body part. The body part is identified by its MIME content-type ('application/emergencyCallData.eCall.MSD+per') in the Content-Type header field of the body part. The body part is assigned a unique identifier which is listed in a Content-ID header field in the body part. The INVITE is marked as containing the MSD by adding (or appending to) a Call-Info header field at the top level of the INVITE. This Call-Info header field contains a CID URL referencing the body part's unique identifier, and a 'purpose' parameter identifying the data as the eCall MSD per the registry entry; the 'purpose' parameter's value is 'emergencyCallData.' plus the root of the MIME type (not including the 'emergencyCallData.' prefix and any suffix such as '+per', so in this case, 'purpose=emergencyCallData.eCall.MSD'.

For NG-eCall, the IVS establishes an emergency call using a Request-URI indicating a manual or automatic eCall; the MNO (or ESInet) recognizes the eCall URN and routes the call to an NG-eCall capable PSAP; the PSAP interpets the vehicle data sent with the call and makes it available to the call taker.

  ///----\\\     IMS emergency call with eCall URN    +------+
     IVS    ----------------------------------------->+ PSAP |
  \\\----///    vehicle data included in call setup   +------+

Figure 2: NG-eCall

This document registers new service URN children within the "sos" subservice. These URNs provide the mechanism by which an eCall is identified, and differentiate between manually and automatically triggered eCalls (which might be subject to different treatment, depending on policy). The two service URNs are: urn:service:sos.ecall.automatic and urn:service:sos.ecall.manual

6.1. Call Routing

The routing applied to eCalls might differ from those of other emergency calls, as eCalls are intended to be handled by PSAPs that support eCall. In regions without ESInets, typically the emergency services authorities and the originating network determine how such calls are routed. In a region that uses ESInets, the originating network passes all types of emergency calls to an ESInet (calls which have a request URI containing the "SOS" service URN). The ESInet is then responsible for routing such calls to the appropriate PSAP.

7. Test Calls

eCall requires the ability to place test calls. These are calls that are recognized and treated to some extent as eCalls but are not given emergency call treatment and are not handled by call takers. The specific handling of test eCalls is not itself standardized; typically, the test call facility allows the IVS or user to verify that an eCall can be successfully established with voice communication. The IVS might also be able to verify that the MSD was successfully received.

A service URN starting with "test." indicates a test call. For eCall, "urn:service:test.sos.ecall" indicates such a test feature. This functionality is defined in [RFC6881].

This document registers "urn:service:test.sos.ecall" for eCall test calls.

The CS-eCall test call facility is a non-emergency number so does not get treated as an emergency call. For NG-eCall, MNOs, emergency authorities, and PSAPs can determine how to treat a vehicle call requesting the "test" service URN so that the desired functionality is tested, but this is outside the scope of this document. (One possibility is that MNOs route such calls as non-emergency calls to a PSAP that supports NG-eCall; the PSAP accepts test calls, sends an MSD acknowledgment, and plays an audio clip (for example, saying that the call reached an eCall PSAP) in addition to supporting media loopback per [RFC6881]).

8. eCall-Specific Control/Metadata

eCall requires the ability for the PSAP to acknowledge successful receipt of an MSD sent by the IVS, and for the PSAP to request that the IVS send an MSD (e.g., the call taker can initiate a request for a new MSD to see if there have been changes in the vehicle's state, e.g., location, direction, number of fastened seatbelts).

The mechanism established in [I-D.ietf-ecrit-additional-data], used in Section 5 of this document to carry the MSD from the IVS to the PSAP, is also used to carry a block of metadata/control data from the PSAP to the IVS. This eCall control block (sometimes referred to as eCall metadata) is an XML structure containing eCall-specific elements. When the PSAP needs to send an eCall control block that is in response to data sent by the IVS in a SIP request (e.g., the MSD in the initial INVITE), the control block can be sent in the SIP response to that request (e.g., the response to the INVITE request). When the PSAP needs to send an eCall control block in other circumstances (e.g., mid-call), the control block can be transmitted from the PSAP to the IVS in a SIP INFO request within the established dialog. The IVS sends the requested data (the MSD) in a new INFO request. This mechanism flexibly allows the PSAP to send eCall-specific data to the IVS and the IVS to respond.

This mechanism requires

  • An XML definition of the eCall control object
  • An extension mechanism by which new elements, attributes, and values can be added to the control object definition
  • A MIME type registration for the control object (so it can be carried in SIP messages and responses)
  • An entry in the Emergency Call Additional Data Blocks sub-registry (established by [I-D.ietf-ecrit-additional-data]) so that the control block can be recognized as emergency call specific data within SIP messages
  • An Info-Package registration per [RFC6086] permitting data blocks registered in the Emergency Call Additional Data Blocks sub-registry (established by [I-D.ietf-ecrit-additional-data]) within Info messages

When the IVS includes an unsolicited MSD in a SIP request (e.g., the initial INVITE), the PSAP sends a metadata/control block indicating successful/unsuccessful receipt of the MSD in the SIP response to the request. This also informs the IVS that an NG-eCall is in operation. If the IVS receives a SIP response without the metadata/control block, it indicates that the SIP dialog is not an NG-eCall. When the IVS sends a solicited MSD (e.g., in a SIP INFO request sent following receipt of a SIP INFO request containing a metadata/control block requesting an MSD), the PSAP does not send a metadata/control block indicating successful or unsuccessful receipt of the MSD. (Normal SIP retransmission handles non-receipt of requested data; if the IVS sends a requested MSD in an INFO request and does not receive a SIP status message for the INFO request, it resends it; if the PSAP requests an MSD and does not receive a SIP status message for the INFO request, it resends it.)

This provides flexibility to handle various circumstances. For example, if a PSAP is unable to accept an eCall (e.g., due to overload or too many calls from the same location), it can reject the INVITE. Since a metadata/control object is also included in the SIP response that rejects the call, the IVS knows if the PSAP received the MSD, and can inform the occupants that the PSAP successfully received the vehicle location and information but can't talk to the occupants at that time. Especially for SIP response codes that indicate an inability to conduct a call (as opposed to a technical inability to process the request), the IVS can also determine that the call was successful on a technical level (e.g., not necessary to retry as a CS-eCall). The SIP response code 600 (Busy Everywhere) can be used to indicate this. Other SIP response codes that can be interpreted in this way include 480 (Temporarily Unavailable), 486 (Busy Here), and 603 (Decline).

8.1. The eCall Control Block

The eCall control block is an XML data structure allowing for acknowledgments and requests. It is carried in a SIP body part with a specific MIME content type. It can be extended via an IANA registry to add additional elements, attributes, and values. Two top-level elements are defined for use within an eCall control block:

ack
Used in a control block sent by the PSAP to acknowledge receipt of a data set sent by the IVS.
request
Used in a control block sent by the PSAP to request the vehicle to perform an action. The only action defined in this document is a request for the IVS to send an MSD.

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

  • Transmit data object

  • None

The <ack> element indicates the object being acknowledged (e.g., the MSD), and reports success or failure.

The <request> element contains attributes to indicate the request and to supply related information. The 'action' attribute is mandatory and indicates the specific action. An IANA registry is created in Section 14.8.1 to contain the allowed values.

Extensibility: New elements, child elements, attributes of new and existing elements, and values for new and existing attributes can be added in the IANA registry created in Section 14.8.2. The registry permits implementors to see what has been added, with a reference to the defining document. (Implementations are not expected to dynamically check the registry.) Implementations MUST ignore unsupported elements, attributes, and values.

8.1.1. The <ack> element

The <ack> element is transmitted by the PSAP to acknowledge receipt of an eCall data object. An <ack> element sent by a PSAP references the unique ID of the data object that was sent by the IVS, and further indicates if the PSAP considers the receipt successful or not.

The <ack> element has the following attributes:

8.1.1.1. Attributes of the <ack> element

The <ack> element has the following attributes:

Name:
ref
Usage:
Mandatory
Type:
anyURI
Description:
References the Content-ID of the body part that contained the data object being acknowledged.
Example:
<ack received="yes" ref="1234567890@atlanta.example.com"/>
Name:
received
Usage:
Conditional: mandatory in an >ack< element sent by a PSAP
Type:
Boolean
Description:
Indicates if the referenced object was successfully received or not
Example:
<ack received="yes" ref="1234567890@atlanta.example.com"/>

8.1.1.2. Child Elements of the <ack> element

The <ack> element has no child elements

8.1.1.3. Ack Examples

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

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

    </EmergencyCallData.eCall.Control>
                
            

Figure 3: Ack Example from PSAP to IVS

8.1.2. The <request> element

A <request> element allows the PSAP to request that the IVS send an MSD. The following attributes are defined:

8.1.2.1. Attributes of the <request> element

The <request> element has the following attributes:

Name:
action
Usage:
Mandatory
Type:
token
Description:
Identifies the action that the vehicle is requested to perform. An IANA registry is established in Section 14.8.1 to contain the allowed values.
Example:
action="send-data"
Name:
datatype
Usage:
Conditional
Type:
token
Description:
Mandatory with a "send-data" action. Specifies the data block that the IVS is requested to transmit, using the same identifier as in the 'purpose' attribute set in a Call-Info header field to point to the data block. Permitted values are contained in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data].
Example:
datatype="eCall.MSD"

8.1.2.2. Request Example

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

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

    </EmergencyCallData.eCall.Control>
                
            

Figure 4: Request Example

9. The emergencyCallData.eCall INFO package

This document registers the 'emergencyCallData.eCall' INFO package.

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

Support for the 'emergencyCallData.eCall' INFO package indicates the ability to receive body parts registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data].

An INFO request message carrying data related to an emergency call has an Info-Package header field set to 'emergencyCallData.eCall' per [RFC6086]. Per [I-D.ietf-ecrit-additional-data], the INFO request message contains one or more Call-Info header fields containing a CID URL referencing the unique identifier of a body part, and a 'purpose' parameter identifying the data. Because the data is being carried in an INFO request message, the body part also carries a Content-Disposition header field set to "Info-Package".

9.1. INFO Package Requirements

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

9.1.1. 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 UAs can use the Info Package."

INFO requests associated with the emergencyCallData.eCall INFO package carry data associated with emergency calls as registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data]. The application is emergency calls established using SIP. The functionality is to carry data, metadata, and control information (requests) between vehicles and PSAPs. Refer to [TBD: THIS DOCUMENT] for more information.

9.1.2. 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 INFO is based on an analysis of the requirements against the intent and effects of INFO versus other approaches (which included SIP MESSAGE, SIP OPTIONS, SIP re-INVITE, media plane transport, and non-SIP protocols). In particular, the transport of emergency call data blocks occurs within a SIP emergency dialog, using the mechanism established in [I-D.ietf-ecrit-additional-data], and is normally carried in the initial INVITE and its response; the use of INFO only occurs when emergency-call-related data needs to be sent mid-call. While MESSAGE could be used, it is not tied to a SIP dialog as is INFO and thus might not be associated with the dialog. SIP OPTIONS or re-INVITE could also be used, but is seen as less clean than INFO. SUBSCRIBE/NOTIFY 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 the 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 MSRP as transport) would be disproportionately large, and further, a high-level application protocol identifying the specific data block being sent within the media plane (as provided by the Call-Info header field parameters and MIME body part content type within INFO) would need to be defined.

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

9.1.3. Info Package Name

The info package name is emergencyCallData.eCall.

9.1.4. Info Package Parameters

None.

9.1.5. SIP Option-Tags

None.

9.1.6. INFO Message Body Parts

Only those body parts registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data] are associated with this INFO package.

When more than one body part is included, they are enclosed in a multipart body part (e.g., multipart/mixed). When a body part is digitally signed or encrypted, it is enclosed in an appropriate body part (e.g., multipart/signed or multipart/encrypted).

The Content-Disposition value of a message body part associated with the emergencyCallData.eCall info package is "info-package".

9.1.7. Info Package Usage Restrictions

None.

9.1.8. Rate of INFO Requests

The rate of SIP INFO requests associated with the emergencyCallData.eCall info package is expected to be quite low (most dialogs are likely to contain zero INFO requests, while others can be expected to carry occasional requests).

9.1.9. Info Package Security Considerations

The MIME content type registation for each data block registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data] contains a discussion of the security and/or privacy considerations specific to that data block. The "Security Considerations" and "Privacy Considerations" sections of [TBD: THIS DOCUMENT] discuss security and privacy considerations of the data carried in eCealls.

9.1.10. Implementation Details

See [TBD: THIS DOCUMENT] for protocol details.

9.1.11. Examples

See [TBD: THIS DOCUMENT] for protocol examples.

10. Examples

Figure 5 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 5: Example of NG-eCall Message Flow

The example, shown in Figure 6, illustrates a SIP eCall INVITE that contains an MSD. For simplicity, the example does not show all SIP headers, nor the 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;
              cid:2345678901@atlanta.example.com;
              purpose=emergencyCallData.eCall.control;
   Accept: application/sdp, application/pidf+xml,
           application/emergencyCallData.eCall.control+xml
   CSeq: 31862 INVITE
   Recv-Info: emergencyCallData.eCall
   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/emergencyCallData.eCall.MSD+per
   Content-ID: 1234567890@atlanta.example.com
   Content-Disposition: by-reference;handling=optional
   Content-Transfer-Encoding: binary

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

    --boundary1--

Figure 6: SIP NG-eCall INVITE

Continuing the example, Figure 7 illustrates a SIP 200 OK response to the INVITE of Figure 6, containing an eCall 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: <sip:+13145551111@example.com>;tag=9fxced76sl
   From: Exemplar PSAP <urn:service:sos.ecall.automatic>
   Call-ID: 3848276298220188511@atlanta.example.com
   Call-Info: cid:2345678901@atlanta.example.com;
              purpose=emergencyCallData.eCall.control;
   Accept: application/sdp, application/pidf+xml,
           application/emergencyCallData.eCall.control+xml,
           application/emergencyCallData.eCall.MSD+per
   CSeq: 31862 INVITE
   Recv-Info: emergencyCallData.eCall
   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.eCall.control+xml
   Content-ID: 2345678901@atlanta.example.com
   Content-Disposition: by-reference;handling=optional

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

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

   </EmergencyCallData.eCall.Control>

   --boundaryX--

Figure 7: 200 OK response to INVITE

11. Security Considerations

The security considerations described in [RFC5069] 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.

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 14.3.

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 might be malformed, might contain unexpected characters, excessively long attribute values, elements, etc.

Since this document depends on [I-D.ietf-ecrit-additional-data], the security considerations discussed there apply here (see especially the discussion of TLS, TLS versions, cypher 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).

12. Privacy Considerations

Since this document builds on [I-D.ietf-ecrit-additional-data], the data structures specified there, and the corresponding privacy considerations discussed there, apply here as well. The MSD carries some additional identifying and personal information (mostly about the vehicle and less about the owner), as well as location information, and so 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 14.2.

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 14.3.

13. XML Schema

This section defines an XML schema for the eCall control block. The text description of the eCall control block in Section 8.1 is normative and supersedes any conflicting aspect of this schema.

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

        <xs:import namespace="http://www.w3.org/XML/1998/namespace"
            schemaLocation="http://www.w3.org/2009/01/xml.xsd"/>

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

        <xs:simpleType name="iana-token">
            <xs:annotation>
                <xs:documentation>Permitted values specified in IANA
                registries</xs:documentation>
            </xs:annotation>
        </xs:simpleType>

        <xs:complexType name="eCallControlType">
            <xs:complexContent>
                <xs:restriction base="xs:anyType">
                    <xs:choice>
                        <xs:element name="request" type="pi:requestType"/>
                        <xs:element name="ack" type="pi:ackType"/>
                        
                        <xs:element type="cx:iana-token"/>

                        <xs:any namespace="##other" 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:any namespace="##other" processContents="lax"
                                minOccurs="0"
                                maxOccurs="unbounded"/>

                        <xs:attribute type="cx:iana-token"/>
                    </xs:sequence>

                    <xs:attribute name="ref"
                                  type="xs:anyURI"
                                  use="required"/>
                    <xs:attribute name="received"
                                  type="xs:boolean"/>
                    <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:any namespace="##other" processContents="lax"
                                minOccurs="0"
                                maxOccurs="unbounded"/>
                        <xs:element type="cx:iana-token"/>
                    </xs:choice>
                    <xs:attribute name="action" type="xs:token" use="required"/>
                    
                    <xs:attribute type="cx:iana-token" minOccurs="0"
                        maxOccurs="unbounded"/>
                    
                    <xs:anyAttribute/>
                </xs:restriction>
            </xs:complexContent>
        </xs:complexType>

    </xs:schema>
        
        

Figure 8: eCall Control Block Schema

14. IANA Considerations

14.1. Service URN Registrations

IANA is requested to register the URN 'urn:service:sos.ecall' under the sub-services 'sos' 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. Two sub-services are registered as well:

urn:service:sos.ecall.manual


Used with an eCall invoked due to manual interaction by a vehicle occupant.
urn:service:sos.ecall.automatic


Used with an eCall invoked automatically, for example, due to a crash or other serious incident.

IANA is also requested to register the URN 'urn:service:test.sos.ecall' under the sub-service 'test' registry defined in Setcion 17.2 of [RFC6881].

14.2. MIME Content-type Registration for 'application/emergencyCallData.eCall.MSD+per'

IANA is requested to add application/emergencyCallData.eCall.MSD+per as a MIME content type, with a reference to this document, in accordance to the procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303 [RFC7303].

  • MIME media type name: application
  • MIME subtype name: emergencyCallData.eCall.MSD+per
  • Mandatory parameters: none
  • Optional parameters: none
  • Encoding scheme: binary
  • Encoding considerations: Uses ASN.1 PER, which is a binary encoding; when transported in SIP, binary content transfer encoding is used.
  • Security considerations: This content 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. In general, it is acceptable for the data to be unprotected while briefly in transit within the Mobile Network Operator (MNO); the MNO is trusted to not permit the data to be accessed by third parties. Sections 7 and Section 8 of [I-D.ietf-ecrit-additional-data] 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)

14.3. MIME Content-type Registration for 'application/emergencyCallData.eCall.control+xml'

IANA is requested to add application/emergencyCallData.eCall.control+xml as a MIME content type, with a reference to this document, in accordance to the procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303 [RFC7303].

  • MIME media type name: application
  • MIME subtype name: emergencyCallData.eCall.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 content 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 14.2, 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 provider, 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 call-back from a PSAP merits additional consideration, since current mechanisms are not ideal for verifying that such a call is indeed a call-back 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]. One potential safeguard, applicable regardless of which end initiated the call and the means of the call, is for the PSAP or emergency service provider to sign the body part using a certificate issued by a known emergency services certificate authority and for which the IVS can verify the root certificate; however, this depends on deployed key infrastructure including a recognized certificate authority, certificate revocation mechanisms, etc.
    • Sections 7 and Section 8 of [I-D.ietf-ecrit-additional-data] contain more discussion.

  • Interoperability considerations: None
  • 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 WG.
  • Change controller: The IETF ECRIT WG.

14.4. Registration of the 'eCall.MSD' entry in the Emergency Call Additional Data Blocks registry

This specification requests IANA to add the 'eCall.MSD' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]), with a reference to this document.

14.5. Registration of the 'eCall.control' entry in the Emergency Call Additional Data Blocks registry

This specification requests IANA to add the 'eCall.control' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]), with a reference to this document.

14.6. Registration of the emergencyCallData.eCall Info Package

IANA is requested to add emergencyCallData.eCall to the Info Packages Registry under "Session Initiation Protocol (SIP) Parameters", with a reference to this document.

14.7. URN Sub-Namespace Registration

14.7.1. Registration for urn:ietf:params:xml:ns:eCall

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

                    
    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 eCall Data</title>
    </head>
    <body>
        <h1>Namespace for eCall Data</h1>
        <p>See [TBD: This document].</p>
    </body>
    </html>
    END

                    

URI:
urn:ietf:params:xml:ns:eCall
Registrant Contact:
IETF, ECRIT working group, <ecrit@ietf.org>, as delegated by the IESG <iesg@ietf.org>.
XML:

14.7.2. Registration for urn:ietf:params:xml:ns:eCall:control

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

            
   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 eCall Data: 
               Control Block</title>
   </head>
   <body>
        <h1>Namespace for eCall Data</h1>
        <h2>Control Block</h2>
   <p>See [TBD: This document].</p>
   </body>
   </html>
   END
   
            

URI:
urn:ietf:params:xml:ns:eCall:control
Registrant Contact:
IETF, ECRIT working group, <ecrit@ietf.org>, as delegated by the IESG <iesg@ietf.org>.
XML:

14.8. Registry creation

This document creates a new registry called 'eCall Control Data'. The following sub-registries are created for this registry.

14.8.1. eCall Control Action Registry

This document creates a new sub-registry called "eCall Control Action Registry". 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 the action 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 an eCall 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 2.

eCall Control Action Registry Initial Values
Name Description
send-data Section Section 8.1.2.1 of this document

14.8.2. eCall Control Extension Registry

This document creates a new sub-registry called "eCall Control Extension Registry". This registry contains elements, attributes, and values for the eCall metadata/control object. As defined in [RFC5226], this registry operates under "Expert Review" rules. The expert should determine that the proposed elements, attributes, and/or values are within the purview of a vehicle, are sufficiently distinguishable, and clearly and fully described. In most cases, a published and stable document is referenced for the description of each element, attribute, or value. New values MUST indicate for which attributes or elements they are appropriate. New attributes MUST indicate in which elements they can appear and to which values that can be set. New elements MUST indicate if they can appear as child elements within other elements, and if so which elements, and/or if they can appear at the top level of an eCall metadata/control object. New elements MUST also describe which attributes and/or sub-elements they can contain and which are optional and which are mandatory. Note that this mechanism allows new items to be added while maintaining compatibility with existing implementations, since unrecognized items are ignored.

The content of this registry includes:

Type:
'Element', 'Attribute', or 'Value'.
Name:
The name of the new element or attribute. Not used for new values.
Description:
A description of the element, attribute, or value. In most cases this will be a reference to a published and stable document.

15. Contributors

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

16. Acknowledgements

We would like to thank Bob Williams and Ban Al-Bakri for their feedback and suggestion; Rex Buddenberg, Lena Chaponniere, Keith Drage, Stephen Edge, Wes George, Christer Holmberg, Ivo Sedlacek, and James Winterbottom for their review and comments; Robert Sparks and Paul Kyzivat for their help with the SIP mechanisms. 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.

17. Changes from Previous Versions

17.1. Changes from draft-ietf-07 to draft-ietf-08

  • eCall MSD now encoded as ASN.1 PER, using binary content transfer encoding
  • Added text to point out aspects of call handling and metadata/control usage, such as use in rejected calls, call-backs, and solicited MSDs
  • Revised use of INFO to require that when a request for an MSD is sent in INFO, the MSD sent in response is in its own INFO, not the response to the requesting INFO
  • Added material to INFO package registation to comply with Section 10 of [RFC6086]
  • Moved material not required by 3GPP into [I-D.ietf-ecrit-car-crash], e.g., some of the eCall metadata/control elements, attributes, and values
  • Revised test call wording to clarify that specific handling is out of scope
  • Revised wording throughout the document to simplify
  • Moved new Section Section 6.1 to be a subsection of Section 6
  • Moved new Section Section 9 to be a main section instead of a subsection of Section 8
  • Revised SIP INFO usage and package registration per advice from Robert Sparks and Paul Kyzivat

17.2. Changes from draft-ietf-06 to draft-ietf-07

  • Fixed typo in Acknowledgements

17.3. Changes from draft-ietf-05 to draft-ietf-06

  • Added additional security and privacy clarifications regarding signed and encrypted data
  • Additional security and privacy text
  • Deleted informative section on ESINets as unnecessary.

17.4. Changes from draft-ietf-04 to draft-ietf-05

  • Reworked the security and privacy considerations material in the document as a whole and in the MIME registation sections of the MSD and control objects
  • Clarified that the <actionResult> element can appear multiple times within an <ack> element
  • Fixed IMS definition
  • Added clarifying text for the 'msgid' attribute

17.5. Changes from draft-ietf-03 to draft-ietf-04

  • Added Privacy Considerations section
  • Reworded most uses of non-normative "may", "should", "must", and "recommended."
  • Fixed nits in examples

17.6. Changes from draft-ietf-02 to draft-ietf-03

  • Added request to enable cameras
  • Improved examples and XML schema
  • Clarifications and wording improvements

17.7. Changes from draft-ietf-01 to draft-ietf-02

  • Added clarifying text reinforcing that the data exchange is for small blocks of data infrequently transmitted
  • Clarified that dynamic media is conveyed using SIP re-INVITE to establish a one-way media stream
  • Clarified that the scope is the needs of eCall within the SIP emergency call environment
  • Added informative statement that the document may be suitable for reuse by other ACN systems
  • Clarified that normative language for the control block applies to both IVS and PSAP
  • Removed 'ref', 'supported-mime', and <media> elements
  • Minor wording improvements and clarifications

17.8. Changes from draft-ietf-00 to draft-ietf-01

  • Added further discussion of test calls
  • Added further clarification to the document scope
  • Mentioned that multi-region vehicles may need to support other crash notification specifications in addition to eCall
  • Added details of the eCall metadata and control functionality
  • Added IANA registration for the MIME content type for the eCall control object
  • Added IANA registries for protocol elements and tokens used in the eCall control object
  • Minor wording improvements and clarifications

17.9. Changes from draft-gellens-03 to draft-ietf-00

  • Renamed from draft-gellens- to draft-ietf-.
  • Added mention of and reference to ETSI TR "Mobile Standards Group (MSG); eCall for VoIP"
  • Added text to Introduction regarding migration/co-existence being out of scope
  • Added mention in Security Considerations that even if the network-supplied location is just the cell site, this can be useful as a sanity check on the IVS-supplied location
  • Minor wording improvements and clarifications

17.10. Changes from draft-gellens-02 to -03

  • Clarifications and editorial improvements.

17.11. Changes from draft-gellens-01 to -02

  • Minor wording improvements
  • Removed ".automatic" and ".manual" from "urn:service:test.sos.ecall" registration and discussion text.

17.12. Changes from draft-gellens-00 to -01

  • Now using 'EmergencyCallData' for purpose parameter values and MIME subtypes, in accordance with changes to [I-D.ietf-ecrit-additional-data]
  • Added reference to RFC 6443
  • Fixed bug that caused Figure captions to not appear

18. References

18.1. Normative References

[EN_16072] CEN, , "Intelligent transport systems - eSafety - Pan-European eCall operating requirements, EN 16072", April 2015.
[I-D.ietf-ecrit-additional-data] Gellens, R., Rosen, B., Tschofenig, H., Marshall, R. and J. Winterbottom, "Additional Data Related to an Emergency Call", Internet-Draft draft-ietf-ecrit-additional-data-38, April 2016.
[msd] CEN, , "Intelligent transport systems -- eSafety -- eCall minimum set of data (MSD), 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.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for Emergency and Other Well-Known Services", RFC 5031, DOI 10.17487/RFC5031, January 2008.
[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.
[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.
[RFC6838] Freed, N., Klensin, J. and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013.
[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.
[RFC7303] Thompson, H. and C. Lilley, "XML Media Types", RFC 7303, DOI 10.17487/RFC7303, July 2014.
[TS22.101] 3GPP, , "3GPP TS 22.101: Technical Specification Group Services and System Aspects; Service aspects; Service principles"

18.2. Informative references

, ", ", "
[CEN]European Committee for Standardization"
[I-D.ietf-ecrit-car-crash] Gellens, R., Rosen, B. and H. Tschofenig, Next-Generation Vehicle-Initiated Emergency Calls", Internet-Draft draft-ietf-ecrit-car-crash-07, February 2016.
[MSG_TR] ETSI, , ETSI Mobile Standards Group (MSG); eCall for VoIP", ETSI Technical Report TR 103 140 V1.1.1 (2014-04), April 2014.
[RFC5012] Schulzrinne, H. and R. Marshall, "Requirements for Emergency Context Resolution with Internet Technologies", RFC 5012, DOI 10.17487/RFC5012, January 2008.
[RFC5069] Taylor, T., 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.
[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.
[RFC7090] Schulzrinne, H., Tschofenig, H., Holmberg, C. and M. Patel, "Public Safety Answering Point (PSAP) Callback", RFC 7090, DOI 10.17487/RFC7090, April 2014.
[RFC7378] Tschofenig, H., Schulzrinne, H. and B. Aboba, "Trustworthy Location", RFC 7378, DOI 10.17487/RFC7378, December 2014.
[SDO-3GPP]3d Generation Partnership Project"
[SDO-ETSI]European Telecommunications Standards Institute (ETSI)"

Authors' Addresses

Randall Gellens Consultant 6755 Mira Mesa Blvd 123-151 San Diego, 92121 US EMail: rg+ietf@randy.pensive.org
Hannes Tschofenig Individual EMail: Hannes.Tschofenig@gmx.net URI: http://www.tschofenig.priv.at