ECRIT B. Rosen
Internet-Draft NeuStar, Inc.
Intended status: Experimental H. Schulzrinne
Expires: May 13, 2013 Columbia U.
H. Tschofenig
Nokia Siemens Networks
November 9, 2012
Data-Only Emergency Calls
draft-ietf-ecrit-data-only-ea-04.txt
Abstract
RFC 6443 'Framework for Emergency Calling Using Internet Multimedia'
describes how devices use the Internet to place emergency calls and
how Public Safety Answering Points (PSAPs) can handle Internet
multimedia emergency calls natively. The exchange of multimedia
traffic typically involves a SIP session establishment starting with
a SIP INVITE that negotiates various parameters for that session.
In some cases, however, the transmission of application data is
everything that is needed. Examples of such environments include a
temperature sensors issuing alerts, or vehicles sending crash data.
Often these alerts are conveyed as one-shot data transmissions and in
some rare cases they may require a session to be established. These
type of interactions are called 'data-only emergency calls'.
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/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 13, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architectural Overview . . . . . . . . . . . . . . . . . . . . 5
4. Protocol Specification . . . . . . . . . . . . . . . . . . . . 8
4.1. CAP Transport . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Profiling of the CAP Document Content . . . . . . . . . . 8
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. 425 (Bad Alert Message) Response Code . . . . . . . . . . 10
5.2. The AlertMsg-Error Header Field . . . . . . . . . . . . . 10
6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8.1. Registration of the 'application/cap+xml' MIME type . . . 17
8.2. IANA Registration for 425 Response Code . . . . . . . . . 18
8.3. IANA Registration of New AlertMsg-Error Header Field . . . 18
8.4. IANA Registration for the SIP AlertMsg-Error Codes . . . . 19
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
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1. Introduction
RFC 6443 [RFC6443] describes how devices use the Internet to place
emergency calls and how Public Safety Answering Points (PSAPs) can
handle Internet multimedia emergency calls natively. The exchange of
multimedia traffic typically involves a SIP session establishment
starting with a SIP INVITE that negotiates various parameters for
that session.
In some cases, however, there is only application data to be conveyed
from the end devices to a PSAP or some other intermediary. Examples
of such environments includes sensors issuing alerts, or vehicles
sending crash data. These messages may be one-shot data
transmissions (i.e., SIP message handling that requires no
establishment of a session) and interactions where a sequence of
messages are transmitted in which case a session setup is useful to
ensure that all messages are indeed routed to the same PSAP. These
type of interactions are called 'data-only emergency calls'.
Data-only emergency calls are nevertheless similar to regular
emergency calls in the sense that they require the emergency
indications, emergency call routing functionality and may even have
the same location requirements. However, the communication
interaction will not lead to the exchange of Real-Time Protocol
packets, such as voice, video data or real-time text.
The Common Alerting Protocol (CAP) [cap] is a document format for
exchanging emergency alerts and public warnings. CAP is mainly used
for conveying alerts and warnings between authorities and from
authorities to citizen/individuals.
This document uses the CAP payload to convey the semantic of a data-
only emergency call. Note that further data may be added using the
already available 'additional data' structure
[I-D.ietf-ecrit-additional-data]. Whenever data can be encoded in
the additional data structure it shall be used.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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3. Architectural Overview
This section illustrates two envisioned usage modes; targeted and
location-based emergency alert routing.
1. Emergency alerts containing only data are targeted to a recipient
responsible for evaluating the next steps, which could include:
1. Sending an alert containing only data toward a Public Safety
Answering Point (PSAP);
2. Establishing a third-party initiated emergency call that
could include audio, video, and data.
2. Emergency alerts targeted to a Service URN used for IP-based
emergency calls where the recipient is not known to the
originator. In this scenario, the alert may contain only data
(e.g., a CAP and a PIDF-LO payload in a SIP MESSAGE).
Figure 1 shows a deployment variant where a sensor, is pre-configured
(using techniques outside the scope of this document) to issue an
alert to an aggregator that processes these messages and performs
whatever steps are necessary to appropriately react on the alert.
For example, a security firm may use different sensor inputs to
dispatch their security staff to a building they protect or to
initiate a third-party emergency call.
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+------------+ +------------+
| Sensor | | Aggregator |
| | | |
+---+--------+ +------+-----+
| |
Sensors |
trigger |
emergency |
alert |
| MESSAGE with CAP |
|----------------------------->|
| |
| Aggregator
| processes
| emergency
| alert
| 200 (OK) |
|<-----------------------------|
| |
| |
Figure 1: Targeted Emergency Alert Routing
In Figure 2 a scenario is shown whereby the alert is routed using
location information and the Service URN. An emergency services
routing proxy (ESRP) may use LoST to determine the next hop proxy to
route the alert message to. A possible receiver is a PSAP and the
recipient of the alert may be call taker. In the generic case, there
is very likely no prior relationship between the originator and the
receiver, e.g. PSAP. A PSAP, for example, is likely to receive and
accept alerts from entities it cannot authorize. This scenario
corresponds more to the classical emergency services use case and the
description in [I-D.ietf-ecrit-phonebcp] is applicable.
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+-----------+ +----------+
+--------+ | ESRP | | PSAP |
| Sensor | | | | |
+---+----+ +---+-------+ +---+------+
| | |
Sensors | |
trigger | |
emergency | |
alert | |
| | |
| | |
| MESSAGE with CAP | |
| (including Service URN, |
| such as urn:service:sos) |
|------------------->| |
| | |
| ESRP performs |
| emergency alert |
| routing |
| | MESSAGE with CAP |
| | (including identity info) |
| |----------------------------->|
| | |
| | PSAP
| | processes
| | emergency
| | alert
| | 200 (OK) |
| |<-----------------------------|
| | |
| 200 (OK) | |
|<-------------------| |
| | |
| | |
Figure 2: Location-Based Emergency Alert Routing
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4. Protocol Specification
4.1. CAP Transport
To convey CAP payloads the SIP MESSAGE [RFC3428] is used for
exchanges where no session establishment is needed, i.e.., one-shot
message exchange, and the SIP INVITE [RFC3261] where the
establishment of session is useful (e.g., when multiple independent
messages have to be logically tied together).
The MIME type is set to 'application/cap+xml'.
If the server does not support the functionality required to fulfill
the request then a 501 Not Implemented MUST be returned by RFC 3261
[RFC3261]. This is the appropriate response when a UAS does not
recognize the request method and is not capable of supporting it for
any user.
The 415 Unsupported Media Type error MUST be returned by RFC 3261
[RFC3261] if the server is refusing to service the request because
the message body of the request is in a format not supported by the
server for the requested method. The server MUST return a list of
acceptable formats using the Accept, Accept-Encoding, or Accept-
Language header field, depending on the specific problem with the
content.
4.2. Profiling of the CAP Document Content
The usage of CAP MUST conform to the specification provided with
[cap]. For the usage with SIP the following additional requirements
are imposed:
sender: A few sub-categories for putting a value in the <sender>
element have to be considered:
Originator is a SIP entity, Author indication irrelevant: When
the alert was created by a SIP-based originator and it is not
useful to be explicit about the author of the alert then the
<sender> element MUST be populated with the SIP URI of the user
agent.
Originator is a non-SIP entity, Author indication irrelevant: In
case that the alert was created by a non-SIP based entity and
the identity of this original sender wants to be preserved then
this identity MUST be placed into the <sender> element. In
this category the it is not useful to be explicit about the
author of the alert. The specific type of identity being used
will depends on the technology being used by the original
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originator.
Author indication relevant: In case the author is different from
the actual originator of the message and this distinction wants
to be preserved then the <sender> element MUST NOT contain the
SIP URI.
incidents: The <incidents> element MUST be present whenever there is
a possibility that alert information needs to be updated. The
initial message will then contain an incident identifier carried
in the <incidents> element. This incident identifier MUST be
chosen in such a way that it is unique for a given <sender,
expires, incidents> combination. Note that the <expires> element
is optional and may not be present.
scope: The value of the <scope> element MUST be set to "Private" as
the alert is not meant for public consumption. The <addresses>
element is, however, not used by this specification since the
message routing is performed by SIP and the respective address
information is already available in other SIP headers. Populating
information twice into different parts of the message may lead to
inconsistency.
parameter: The <parameter> element MAY contain additional
information specific to the sensor.
area: It is RECOMMENDED to omit this element when constructing a
message. In case that the CAP message already contained an <area>
element then the specified location information MUST be copied
into the PIDF-LO structure of the 'geolocation' header.
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5. Error Handling
This section defines a new error response code and a header field for
additional information.
5.1. 425 (Bad Alert Message) Response Code
This SIP extension creates a new location-specific response code,
defined as follows,
425 (Bad Alert Message)
The 425 response code is a rejection of the request due to its
included alert content, indicating that it was malformed or not
satisfactory for the recipient's purpose.
A SIP intermediary can also reject an alert it receives from a UA
when it understands that the provided alert is malformed.
Section 5.2 describes an AlertMsg-Error header field with more
details about what was wrong with the alert message in the request.
This header field MUST be included in the 425 response.
It is only appropriate to generate a 425 response when the responding
entity has no other information in the request that are usable by the
responder.
A 425 response code MUST NOT be sent in response to a request that
lacks an alert message entirely, as the user agent in that case may
not support this extension at all.
A 425 response is a final response within a transaction, and MUST NOT
terminate an existing dialog.
5.2. The AlertMsg-Error Header Field
The AlertMsg-Error header provides additional information about what
was wrong with the original request. In some cases the provided
information will be used for debugging purposes.
The AlertMsg-Error header field has the following ABNF [RFC5234]:
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message-header /= AlertMsg-Error
; (message-header from 3261)
AlertMsg-Error = "AlertMsg-Error" HCOLON
ErrorValue
ErrorValue = error-code
*(SEMI error-params)
error-code = 1*3DIGIT
error-params = error-code-text
/ generic-param ; from RFC3261
error-code-text = "code" EQUAL quoted-string ; from RFC3261
HCOLON, SEMI, and EQUAL are defined in RFC3261 [RFC3261]. DIGIT is
defined in RFC5234 [RFC5234].
The AlertMsg-Error header field MUST contain only one ErrorValue to
indicate what was wrong with the alert payload the recipient
determined was bad.
The ErrorValue contains a 3-digit error code indicating what was
wrong with the alert in the request. This error code has a
corresponding quoted error text string that is human understandable.
The text string are OPTIONAL, but RECOMMENDED for human readability,
similar to the string phrase used for SIP response codes. That said,
the strings are complete enough for rendering to the user, if so
desired. The strings in this document are recommendations, and are
not standardized - meaning an operator can change the strings - but
MUST NOT change the meaning of the error code. Similar to how RFC
3261 specifies, there MUST NOT be more than one string per error
code.
The AlertMsg-Error header field MAY be included in any response as an
alert message was in the request part of the same transaction. For
example, a UA includes an alert in an MESSAGE to a PSAP. The PSAP
can accept this MESSAGE, thus creating a dialog, even though his UA
determined the alert message contained in the MESSAGE was bad. The
PSAP merely includes an AlertMsg-Error header value in the 200 OK to
the MESSAGE informing the UA that the MESSAGE was accepted but the
alert provided was bad.
If, on the other hand, the PSAP cannot accept the MESSAGE without a
suitable alert message, a 425 response is sent.
A SIP intermediary that requires the UA's alert message in order to
properly process the MESSAGE may also sends a 425 with a AlertMsg-
Error code.
This document defines an initial list of error code ranges for any
SIP response, including provisional responses (other than 100 Trying)
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and the new 425 response. There MUST be no more than one AlertMsg-
Error code in a SIP response.
AlertMsg-Error: 100 ; code="Cannot Process the Alert Payload"
AlertMsg-Error: 101 ; code="Alert Payload was not present or could
not be found"
AlertMsg-Error: 102 ; code="Not enough information to determine the
purpose of the alert"
AlertMsg-Error: 103 ; code="Alert Payload was corrupted"
Additionally, if an LR cannot or chooses not to process the alert
message from a SIP request, a 500 (Server Internal Error) SHOULD be
used with or without a configurable Retry-After header field.
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6. Example
Figure 3 shows a CAP document indicating a BURGLARY alert issued by a
sensor called 'sensor1@domain.com'. The location of the sensor can
be obtained from the attached location information provided via the
'geolocation' header contained in the SIP MESSAGE structure.
Additionally, the sensor provided some data long with the alert
message using proprietary information elements only to be processed
by the receiver, a SIP entity acting as an aggregator. This example
reflects the description in Figure 1.
MESSAGE sip:aggregator@domain.com SIP/2.0
Via: SIP/2.0/TCP sensor1.domain.com;branch=z9hG4bK776sgdkse
Max-Forwards: 70
From: sip:sensor1@domain.com;tag=49583
To: sip:aggregator@domain.com
Call-ID: asd88asd77a@1.2.3.4
Geolocation: <cid:abcdef@domain.com>
;routing-allowed=yes
Supported: geolocation
Accept: application/pidf+xml, application/cap+xml
CSeq: 1 MESSAGE
Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ...
--boundary1
Content-Type: cap+xml
Content-ID: <abcdef2@domain.com>
<?xml version="1.0" encoding="UTF-8"?>
<alert xmlns="urn:oasis:names:tc:emergency:cap:1.1">
<identifier>S-1</identifier>
<sender>sip:sensor1@domain.com</sender>
<sent>2008-11-19T14:57:00-07:00</sent>
<status>Actual</status>
<msgType>Alert</msgType>
<scope>Private</scope>
<incidents>abc1234</incidents>
<info>
<category>Security</category>
<event>BURGLARY</event>
<urgency>Expected</urgency>
<certainty>Likely</certainty>
<severity>Moderate</severity>
<senderName>SENSOR 1</senderName>
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<parameter>
<valueName>SENSOR-DATA-NAMESPACE1</valueName>
<value>123</value>
</parameter>
<parameter>
<valueName>SENSOR-DATA-NAMESPACE2</valueName>
<value>TRUE</value>
</parameter>
</info>
</alert>
--boundary1
Content-Type: application/pidf+xml
Content-ID: <abcdef2@domain.com>
<?xml version="1.0" encoding="UTF-8"?>
<presence
xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
xmlns:gbp="urn:ietf:params:xml:ns:pidf:geopriv10:basicPolicy"
xmlns:cl="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
xmlns:gml="http://www.opengis.net/gml"
xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
entity="pres:alice@atlanta.example.com">
<dm:device id="sensor">
<gp:geopriv>
<gp:location-info>
<gml:location>
<gml:Point srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>32.86726 -97.16054</gml:pos>
</gml:Point>
</gml:location>
</gp:location-info>
<gp:usage-rules>
<gbp:retransmission-allowed>false
</gbp:retransmission-allowed>
<gbp:retention-expiry>2010-11-14T20:00:00Z
</gbp:retention-expiry>
</gp:usage-rules>
<gp:method>802.11</gp:method>
</gp:geopriv>
<dm:timestamp>2010-11-04T20:57:29Z</dm:timestamp>
</dm:device>
</presence>
--boundary1--
Figure 3: Example Message conveying an Alert
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7. Security Considerations
This section discusses security considerations when SIP user agents
issue emergency alerts utilizing CAP. Location specific threats are
not unique to this document and are discussed in
[I-D.ietf-ecrit-trustworthy-location] and [RFC6442].
The ECRIT emergency services architecture [I-D.ietf-ecrit-phonebcp]
considers classical individual-to-authority emergency calling and the
identity of the emergency caller does not play a role at the time of
the call establishment itself, i.e., a response to the emergency call
will not depend on the identity of the caller. In case of emergency
alerts generated by devices, like sensors, the processing may be
different in order to reduce the number of falsely generated
emergency alerts. Alerts may get triggered based on certain sensor
input that may have been caused by other factors than the actual
occurrence of an alert relevant event. For example, a sensor may
simply be malfunctioning. For this purpose not all alert messages
are directly sent to a PSAP but are rather pre-processed by a
separate entity, potentially under supervision by a human, to filter
alerts and potentially correlate received alerts with others to
obtain a larger picture of the ongoing situation. These two message
routing examples are shown in Figure 1 and in Figure 2.
In any case, for alerts that are initiated by sensors the identity
may play an important role in deciding whether to accept or ignore an
incoming alert message. With the scenario shown in Figure 1 it is
very likely that only authorized sensor input will be processed. For
this purpose it needs to be ensured that no alert messages from an
unknown origin are accepted. Two types of information elements can
be used for this purpose:
1. SIP itself provides security mechanisms that allow the
verification of the originator's identity. These mechanisms can
be re-used, such as P-Asserted-Identity [RFC3325] or SIP Identity
[RFC4474]. The latter provides a cryptographic assurance while
the former relies on a chain of trust model.
2. CAP provides additional security mechanisms and the ability to
carry additional information about the sender's identity.
Section 3.3.2.1 of [cap] specifies the signing algorithms of CAP
documents.
In addition to the desire to perform identity-based access control
the classical communication security threats need to be considered,
including integrity protection to prevent forgery and replay of alert
messages in transit. To deal with replay of alerts a CAP document
contains the mandatory <identifier>, <sender>, <sent> elements and an
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optional <expire> element. These attributes make the CAP document
unique for a specific sender and provide time restrictions. An
entity that has received a CAP message already within the indicated
timeframe is able to detect a replayed message and, if the content of
that message is unchanged, then no additional security vulnerability
is created. Additionally, it is RECOMMENDED to make use of SIP
security mechanisms, such as SIP Identity [RFC4474], to tie the CAP
message to the SIP message. To provide protection of the entire SIP
message exchange between neighboring SIP entities the usage of TLS is
mandatory.
Note that none of the security mechanism in this document protect
against a compromised sensor sending crafted alerts.
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8. IANA Considerations
8.1. Registration of the 'application/cap+xml' MIME type
To: ietf-types@iana.org
Subject: Registration of MIME media type application/ cap+xml
MIME media type name: application
MIME subtype name: cap+xml
Required parameters: (none)
Optional parameters: charset; Indicates the character encoding of
enclosed XML. Default is UTF-8 [RFC3629].
Encoding considerations: Uses XML, which can employ 8-bit
characters, depending on the character encoding used. See RFC
3023 [RFC3023], Section 3.2.
Security considerations: This content type is designed to carry
payloads of the Common Alerting Protocol (CAP).
Interoperability considerations: This content type provides a way to
convey CAP payloads.
Published specification: RFC XXX [Replace by the RFC number of this
specification].
Applications which use this media type: Applications that convey
alerts and warnings according to the CAP standard.
Additional information: OASIS has published the Common Alerting
Protocol at http://www.oasis-open.org/committees/
documents.php&wg_abbrev=emergency
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Person and email address to contact for further information: Hannes
Tschofenig, Hannes.Tschofenig@nsn.com
Intended usage: Limited use
Author/Change controller: IETF ECRIT working group
Other information: This media type is a specialization of
application/xml RFC 3023 [RFC3023], and many of the considerations
described there also apply to application/cap+xml.
8.2. IANA Registration for 425 Response Code
In the SIP Response Codes registry, the following is added
Reference: RFC-XXXX (i.e., this document)
Response code: 425 (recommended number to assign)
Default reason phrase: Bad Alert Message
Registry:
Response Code Reference
------------------------------------------ ---------
Request Failure 4xx
425 Bad Alert Message [this doc]
This SIP Response code is defined in Section 5.
8.3. IANA Registration of New AlertMsg-Error Header Field
The SIP AlertMsg-error header field is created by this document, with
its definition and rules in Section 5, to be added to the IANA sip-
parameters registry with two actions:
1. Update the Header Fields registry with
Registry:
Header Name compact Reference
----------------- ------- ---------
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AlertMsg-Error [this doc]
2. In the portion titled "Header Field Parameters and Parameter
Values", add
Predefined
Header Field Parameter Name Values Reference
----------------- ------------------- ---------- ---------
AlertMsg-Error code yes [this doc]
8.4. IANA Registration for the SIP AlertMsg-Error Codes
This document creates a new registry for SIP, called "AlertMsg-Error
Codes". AlertMsg-Error codes provide reason for the error discovered
by recipients, categorized by action to be taken by error recipient.
The initial values for this registry are shown below.
Registry Name: AlertMsg-Error Codes
Reference: [this doc]
Registration Procedures: Specification Required
Code Default Reason Phrase Reference
---- --------------------------------------------------- ---------
100 "Cannot Process the Alert Payload" [this doc]
101 "Alert Payload was not present or could not be found" [this doc]
102 "Not enough information to determine
the purpose of the alert" [this doc]
103 "Alert Payload was corrupted" [this doc]
Details of these error codes are in Section 5.
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9. Acknowledgments
The authors would like to thank the participants of the Early Warning
adhoc meeting at IETF#69 for their feedback. Additionally, we would
like to thank the members of the NENA Long Term Direction Working
Group for their feedback.
Additionally, we would like to thank Martin Thomson, James
Winterbottom, Shida Schubert, Bernard Aboba, and Marc Linsner for
their review comments.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[cap] Jones, E. and A. Botterell, "Common Alerting Protocol v.
1.1", October 2005.
[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
Types", RFC 3023, January 2001.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[I-D.ietf-ecrit-phonebcp]
Rosen, B. and J. Polk, "Best Current Practice for
Communications Services in support of Emergency Calling",
draft-ietf-ecrit-phonebcp-20 (work in progress),
September 2011.
[RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance
for the Session Initiation Protocol", RFC 6442,
December 2011.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
and D. Gurle, "Session Initiation Protocol (SIP) Extension
for Instant Messaging", RFC 3428, December 2002.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[I-D.ietf-ecrit-additional-data]
Rosen, B., Tschofenig, H., and R. Marshall, "Additional
Data related to an Emergency Call",
draft-ietf-ecrit-additional-data-05 (work in progress),
October 2012.
10.2. Informative References
[I-D.ietf-ecrit-trustworthy-location]
Tschofenig, H., Schulzrinne, H., and B. Aboba,
Rosen, et al. Expires May 13, 2013 [Page 21]
Internet-Draft Data-Only Emergency Calls November 2012
"Trustworthy Location",
draft-ietf-ecrit-trustworthy-location-04 (work in
progress), October 2012.
[RFC4474] Peterson, J. and C. Jennings, "Enhancements for
Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474, August 2006.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
November 2002.
[RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
"Framework for Emergency Calling Using Internet
Multimedia", RFC 6443, December 2011.
Rosen, et al. Expires May 13, 2013 [Page 22]
Internet-Draft Data-Only Emergency Calls November 2012
Authors' Addresses
Brian Rosen
NeuStar, Inc.
470 Conrad Dr
Mars, PA 16046
US
Phone:
Email: br@brianrosen.net
Henning Schulzrinne
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
US
Phone: +1 212 939 7004
Email: hgs+ecrit@cs.columbia.edu
URI: http://www.cs.columbia.edu
Hannes Tschofenig
Nokia Siemens Networks
Linnoitustie 6
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
Rosen, et al. Expires May 13, 2013 [Page 23]
