< draft-ietf-ecrit-data-only-ea-10.txt		draft-ietf-ecrit-data-only-ea-11.txt >
	ECRIT B. Rosen		ECRIT B. Rosen
	Internet-Draft NeuStar, Inc.		Internet-Draft NeuStar, Inc.
	Intended status: Standards Track H. Schulzrinne		Intended status: Standards Track H. Schulzrinne
	Expires: February 12, 2016 Columbia U.		Expires: September 2, 2016 Columbia U.
	H. Tschofenig		H. Tschofenig
	August 11, 2015		ARM Limited
			R. Gellens
			March 1, 2016
	Data-Only Emergency Calls		Data-Only Emergency Calls
	draft-ietf-ecrit-data-only-ea-10.txt		draft-ietf-ecrit-data-only-ea-11.txt
	Abstract		Abstract
	RFC 6443 'Framework for Emergency Calling Using Internet Multimedia'		RFC 6443 'Framework for Emergency Calling Using Internet Multimedia'
	describes how devices use the Internet to place emergency calls and		describes how devices use the Internet to place emergency calls and
	how Public Safety Answering Points (PSAPs) can handle Internet		how Public Safety Answering Points (PSAPs) handle Internet multimedia
	multimedia emergency calls natively. The exchange of multimedia		emergency calls natively. The exchange of multimedia traffic for
	traffic typically involves a SIP session establishment starting with		emergency services involves a SIP session establishment starting with
	a SIP INVITE that negotiates various parameters for that session.		a SIP INVITE that negotiates various parameters for that session.
	In some cases, however, the transmission of application data is		In some cases, however, the transmission of application data is all
	everything that is needed. Examples of such environments include a		that is needed. Examples of such environments include alerts issued
	temperature sensors issuing alerts, or vehicles sending crash data.		by a temperature sensor, burglar alarm, or chemical spill sensor.
	Often these alerts are conveyed as one-shot data transmissions.		Often these alerts are conveyed as one-shot data transmissions.
	These type of interactions are called 'data-only emergency calls'.		These type of interactions are called 'data-only emergency calls'.
	This document describes a container for the data based on the Common		This document describes a container for the data based on the Common
	Alerting Protocol (CAP) and its transmission using the SIP MESSAGE		Alerting Protocol (CAP) and its transmission using the SIP MESSAGE
	transaction.		transaction.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	skipping to change at page 1, line 46 ¶		skipping to change at page 1, line 48 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on February 12, 2016.		This Internet-Draft will expire on September 2, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2016 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 40 ¶		skipping to change at page 2, line 40 ¶
	5.1. 425 (Bad Alert Message) Response Code . . . . . . . . . . 9		5.1. 425 (Bad Alert Message) Response Code . . . . . . . . . . 9
	5.2. The AlertMsg-Error Header Field . . . . . . . . . . . . . 9		5.2. The AlertMsg-Error Header Field . . . . . . . . . . . . . 9
	6. Updates to the CAP Message . . . . . . . . . . . . . . . . . 11		6. Updates to the CAP Message . . . . . . . . . . . . . . . . . 11
	7. Call Backs . . . . . . . . . . . . . . . . . . . . . . . . . 11		7. Call Backs . . . . . . . . . . . . . . . . . . . . . . . . . 11
	8. Handling Large Amounts of Data . . . . . . . . . . . . . . . 11		8. Handling Large Amounts of Data . . . . . . . . . . . . . . . 11
	9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 11		9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 15		10. Security Considerations . . . . . . . . . . . . . . . . . . . 15
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
	11.1. Registration of the 'application/emergencyCall.cap+xml'		11.1. Registration of the 'application/emergencyCall.cap+xml'
	MIME type . . . . . . . . . . . . . . . . . . . . . . . 17		MIME type . . . . . . . . . . . . . . . . . . . . . . . 17
	11.2. IANA Registration of Additional Data Block . . . . . . . 18		11.2. IANA Registration of 'cap' Additional Data Block . . . . 18
	11.3. IANA Registration for 425 Response Code . . . . . . . . 18		11.3. IANA Registration for 425 Response Code . . . . . . . . 18
	11.4. IANA Registration of New AlertMsg-Error Header Field . . 19		11.4. IANA Registration of New AlertMsg-Error Header Field . . 19
	11.5. IANA Registration for the SIP AlertMsg-Error Codes . . . 19		11.5. IANA Registration for the SIP AlertMsg-Error Codes . . . 19
	12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20		12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
	13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20		13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
	13.1. Normative References . . . . . . . . . . . . . . . . . . 20		13.1. Normative References . . . . . . . . . . . . . . . . . . 20
	13.2. Informative References . . . . . . . . . . . . . . . . . 21		13.2. Informative References . . . . . . . . . . . . . . . . . 21
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
	1. Introduction		1. Introduction
	RFC 6443 [RFC6443] describes how devices use the Internet to place		RFC 6443 [RFC6443] describes how devices use the Internet to place
	emergency calls and how Public Safety Answering Points (PSAPs) can		emergency calls and how Public Safety Answering Points (PSAPs) handle
	handle Internet multimedia emergency calls natively. The exchange of		Internet multimedia emergency calls natively. The exchange of
	multimedia traffic typically involves a SIP session establishment		multimedia traffic for emergency services involves a SIP session
	starting with a SIP INVITE that negotiates various parameters for		establishment starting with a SIP INVITE that negotiates various
	that session.		parameters for that session.
	In some cases, however, there is only application data to be conveyed		In some cases, however, there is only application data to be conveyed
	from the end devices to a PSAP or some other intermediary. Examples		from the end devices to a PSAP or an intermediary. Examples of such
	of such environments includes sensors issuing alerts, or vehicles		environments includes sensors issuing alerts, or vehicles sending
	sending crash data. These messages may be one-shot alerts to		crash data. These messages may be one-shot alerts to emergency
	emergency authorities and do not require establishment of a session.		authorities and do not require establishment of a session. These
	These type of interactions are called 'data-only emergency calls'.		type of interactions are called 'data-only emergency calls'. In this
	In this document, we use the term "call" so that similarities between		document, we use the term "call" so that similarities between data-
	full sessions with interactive media can be exploited.		only (non-interactive) alerts and sessions with interactive media are
			more obvious.
	Data-only emergency calls are similar to regular emergency calls in		Data-only emergency calls are similar to regular emergency calls in
	the sense that they require the emergency indications, emergency call		the sense that they require the emergency indications, emergency call
	routing functionality and may even have the same location		routing functionality and may even have the same location
	requirements. However, the communication interaction will not lead		requirements. However, the communication interaction will not lead
	to the exchange of interactive media, that is, Real-Time Protocol		to the exchange of interactive media, that is, Real-Time Protocol
	packets, such as voice, video data or real-time text.		packets, such as voice, video data or real-time text.
	The Common Alerting Protocol (CAP) [cap] is a document format for		The Common Alerting Protocol (CAP) [cap] is a document format for
	exchanging emergency alerts and public warnings. CAP is mainly used		exchanging emergency alerts and public warnings. CAP is mainly used
	for conveying alerts and warnings between authorities and from		for conveying alerts and warnings between authorities and from
	authorities to citizen/individuals. This document is concerned with		authorities to citizen/individuals. This document is concerned with
	citizen to authority "alerts", where the alert is sent without any		citizen to authority "alerts", where the alert is a call without any
	interactive media.		interactive media.
	This document describes a method of including a CAP message in a SIP		This document describes a method of including a CAP message in a SIP
	transaction, either by value (CAP message is in the body of the		transaction, either by value (the CAP message is in the body of the
	message, using a CID) or by reference (A URI is included in the		message, using a CID) or by reference (a URI is included in the
	message, which when dereferenced returns the CAP message) by defining		message, which when dereferenced returns the CAP message) by defining
	it as a block of "additional data" as defined in		it as a block of "additional data" as defined in
	[I-D.ietf-ecrit-additional-data]. The additional data mechanism is		[I-D.ietf-ecrit-additional-data]. The additional data mechanism is
	also used to send alert specific data beyond that available in the		also used to send alert specific data beyond that available in the
	CAP message. This document also describes how a SIP MESSAGE		CAP message. This document also describes how a SIP MESSAGE
	[RFC3428] transaction can be used to send a data-only call.		[RFC3428] transaction can be used to send a data-only call.
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	3. Architectural Overview		3. Architectural Overview
	This section illustrates two envisioned usage modes; targeted and		This section illustrates two envisioned usage modes: targeted and
	location-based emergency alert routing.		location-based emergency alert routing.
	1. Emergency alerts containing only data are targeted to a		1. Emergency alerts containing only data are targeted to an
	intermediary recipient responsible for evaluating the next steps.		intermediary recipient responsible for evaluating the next steps.
	These steps could include:		These steps could include:
	1. Sending a call containing only data toward a Public Safety		1. Sending a non-interactive call containing only data toward a
	Answering Point (PSAP);		Public Safety Answering Point (PSAP);
	2. Establishing a third-party initiated emergency call towards a		2. Establishing a third-party initiated emergency call towards a
	PSAP that could include audio, video, and data.		PSAP that could include audio, video, and data.
	2. Emergency alerts may be targeted to a Service URN used for IP-		2. Emergency alerts may be targeted to a Service URN used for IP-
	based emergency calls where the recipient is not known to the		based emergency calls where the recipient is not known to the
	originator. In this scenario, the alert may contain only data		originator. In this scenario, the alert may contain only data
	(e.g., a CAP, Geolocation header and one or more Call-Info		(e.g., a CAP, Geolocation header field and one or more Call-Info
	headers containing Additional Data		header fields containing Additional Data
	[I-D.ietf-ecrit-additional-data] in a SIP MESSAGE).		[I-D.ietf-ecrit-additional-data] in a SIP MESSAGE).
	Figure 1 shows a deployment variant where a sensor, is pre-configured		Figure 1 shows a deployment variant where a sensor is pre-configured
	(using techniques outside the scope of this document) to issue an		(using techniques outside the scope of this document) to issue an
	alert to an aggregator that processes these messages and performs		alert to an aggregator that processes these messages and performs
	whatever steps are necessary to appropriately react on the alert.		whatever steps are necessary to appropriately react to the alert.
	For example, a security firm may use different sensor inputs to		For example, a security firm may use different sensor inputs to
	dispatch their security staff to a building they protect or to		dispatch their security staff to a building they protect or to
	initiate a third-party emergency call.		initiate a third-party emergency call.
	+------------+ +------------+		+------------+ +------------+
	| Sensor | | Aggregator |		| Sensor | | Aggregator |
	| | | |		| | | |
	+---+--------+ +------+-----+		+---+--------+ +------+-----+
	| |		| |
	Sensors |		Sensors |
	skipping to change at page 5, line 29 ¶		skipping to change at page 5, line 29 ¶
	| emergency		| emergency
	| alert		| alert
	| 200 (OK) |		| 200 (OK) |
	|<-----------------------------|		|<-----------------------------|
	| |		| |
	| |		| |
	Figure 1: Targeted Emergency Alert Routing		Figure 1: Targeted Emergency Alert Routing
	In Figure 2 a scenario is shown whereby the alert is routed using		In Figure 2 a scenario is shown whereby the alert is routed using
	location information and the Service URN. An emergency services		location information and a Service URN. An emergency services
	routing proxy (ESRP) may use LoST to determine the next hop proxy to		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		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		recipient of the alert may be a call taker. In the generic case,
	is very likely no prior relationship between the originator and the		there is very likely no prior relationship between the originator and
	receiver, e.g. PSAP. A PSAP, for example, is likely to receive and		the receiver, e.g., a PSAP. A PSAP, for example, is likely to
	accept alerts from entities it cannot authorize. This scenario		receive and accept alerts from entities it cannot authorize. This
	corresponds more to the classical emergency services use case and the		scenario corresponds to the classic emergency services use case and
	description in [RFC6881] is applicable. In this use case, the only		the description in [RFC6881] is applicable. In this use case, the
	difference between an emergency call, and an emergency data-only call		only difference between an emergency call and an emergency data-only
	is that the former uses INVITE, creates a session and negotiates one		call is that the former uses INVITE, creates a session, and
	or more media streams, while the latter uses MESSAGE, does not create		negotiates one or more media streams, while the latter uses MESSAGE,
	a session and does not have media.		does not create a session, and does not have media.
	+-----------+ +----------+		+-----------+ +----------+
	+--------+ | ESRP | | PSAP |		+--------+ | ESRP | | PSAP |
	| Sensor | | | | |		| Sensor | | | | |
	+---+----+ +---+-------+ +---+------+		+---+----+ +---+-------+ +---+------+
	| | |		| | |
	Sensors | |		Sensors | |
	trigger | |		trigger | |
	emergency | |		emergency | |
	alert | |		alert | |
	skipping to change at page 6, line 46 ¶		skipping to change at page 6, line 46 ¶
	|<-------------------| |		|<-------------------| |
	| | |		| | |
	| | |		| | |
	Figure 2: Location-Based Emergency Alert Routing		Figure 2: Location-Based Emergency Alert Routing
	4. Protocol Specification		4. Protocol Specification
	4.1. CAP Transport		4.1. CAP Transport
	A CAP message may be sent on the initial message of any SIP		A CAP message may be sent in the initial message of any SIP
	transaction. However, this document only describes specific behavior		transaction. However, this document only addresses sending a CAP
	when used with a SIP INVITE that would accompany a normal emergency		message in a SIP INVITE that initiates an emergency call, or in a SIP
	call and a SIP MESSAGE transaction for a one-shot, data-only		MESSAGE transaction for a one-shot, data-only emergency call.
	emergency call. Behavior with other transactions is not defined.		Behavior with other transactions is not defined.
	The CAP message included in a SIP message as an additional-data block		The CAP message is included in a SIP message as an additional-data
	[I-D.ietf-ecrit-additional-data]. Accordingly, it is introduced to		block [I-D.ietf-ecrit-additional-data]. Accordingly, it is
	the SIP message with a Call-Info header with a purpose of		introduced to the SIP message with a Call-Info header field with a
	"emergencyCall.cap". The header may contain a URI that is used by		purpose of "emergencyCall.cap". The header field may contain a URI
	the recipient (or in some cases, an intermediary) to obtain the CAP		that is used by the recipient (or in some cases, an intermediary) to
	message. Alternative, the Call-Info header may contain a Content		obtain the CAP message. Alternative, the Call-Info header field may
	Indirect url [RFC2392] and the CAP message included in the body of		contain a Content Indirect url [RFC2392] and the CAP message included
	the message. In either case, the CAP message is located in a MIME		in the body of the message. In either case, the CAP message is
	block. The MIME type is set to 'application/emergencyCall.cap+xml'.		located in a MIME block of the type 'application/
			emergencyCall.cap+xml'.
	If the server does not support the functionality required to fulfill		If the SIP server does not support the functionality required to
	the request then a 501 Not Implemented MUST be returned as specified		fulfill the request then a 501 Not Implemented MUST be returned as
	in RFC 3261 [RFC3261]. This is the appropriate response when a UAS		specified in RFC 3261 [RFC3261]. This is the appropriate response
	does not recognize the request method and is not capable of		when a UAS does not recognize the request method and is not capable
	supporting it for any user.		of supporting it for any user.
	The 415 Unsupported Media Type error MUST be returned as specified in		The 415 Unsupported Media Type error MUST be returned as specified in
	RFC 3261 [RFC3261] if the server is refusing to service the request		RFC 3261 [RFC3261] if the SIP server is refusing to service the
	because the message body of the request is in a format not supported		request because the message body of the request is in a format not
	by the server for the requested method. The server MUST return a		supported by the server for the requested method. The server MUST
	list of acceptable formats using the Accept, Accept-Encoding, or		return a list of acceptable formats using the Accept, Accept-
	Accept-Language header field, depending on the specific problem with		Encoding, or Accept-Language header fields, depending on the specific
	the content.		problem with the content.
	4.2. Profiling of the CAP Document Content		4.2. Profiling of the CAP Document Content
	The usage of CAP MUST conform to the specification provided with		The usage of CAP MUST conform to the specification provided with
	[cap]. For the usage with SIP the following additional requirements		[cap]. For usage with SIP the following additional requirements are
	are imposed:		imposed:
	sender: A few sub-categories for putting a value in the <sender>		sender: The following restrictions and conditions apply to setting
	element have to be considered:		the value of the <sender> element:
	Originator is a SIP entity, Author indication irrelevant: When		Originator is a SIP entity, Author indication irrelevant: When
	the alert was created by a SIP-based originator and it is not		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		useful to be explicit about the author of the alert, then the
	<sender> element MUST be populated with the SIP URI of the user		<sender> element MUST be populated with the SIP URI of the user
	agent.		agent.
	Originator is a non-SIP entity, Author indication irrelevant: In		Originator is a non-SIP entity, Author indication irrelevant:
	case that the alert was created by a non-SIP based entity and		When the alert was created by a non-SIP based entity and the
	the identity of this original sender wants to be preserved then		identity of this original sender is to be preserved, then this
	this identity MUST be placed into the <sender> element. In		identity MUST be placed into the <sender> element. In this
	this category the it is not useful to be explicit about the		situation it is not useful to be explicit about the author of the
	author of the alert. The specific type of identity being used		alert. The specific type of identity being used will depend on
	will depends on the technology being used by the original		the technology used by the original originator.
	originator.
	Author indication relevant: In case the author is different from		Author indication relevant: When the author is different from the
	the actual originator of the message and this distinction		actual originator of the message and this distinction should be
	should be preserved then the <sender> element MUST NOT contain		preserved, then the <sender> element MUST NOT contain the SIP URI
	the SIP URI of the user agent.		of the user agent.
	incidents: The <incidents> element MUST be present. This incident		incidents: The <incidents> element MUST be present. This incident
	identifier MUST be chosen in such a way that it is unique for a		identifier MUST be chosen in such a way that it is unique for a
	given <sender, expires, incidents> combination. Note that the		given <sender, expires, incidents> combination. Note that the
	<expires> element is optional and may not be present.		<expires> element is optional and may not be present.
	scope: The value of the <scope> element MAY be set to "Private" if		scope: The value of the <scope> element MAY be set to "Private" if
	the alert is not meant for public consumption. The <addresses>		the alert is not meant for public consumption. The <addresses>
	element is, however, not used by this specification since the		element is, however, not used by this specification since the
	message routing is performed by SIP and the respective address		message routing is performed by SIP and the respective address
	information is already available in other SIP headers. Populating		information is already available in other SIP header fields.
	information twice into different parts of the message may lead to		Populating information twice into different parts of the message
	inconsistency.		may lead to inconsistency.
	parameter: The <parameter> element MAY contain additional		parameter: The <parameter> element MAY contain additional
	information specific to the sendor.		information specific to the sendor.
	area: It is RECOMMENDED to omit this element when constructing a		area: It is RECOMMENDED to omit this element when constructing a
	message. In case that the CAP message already contained an <area>		message. If the CAP message already contains an <area> element,
	element then the specified location information SHOULD be copied		then the specified location information SHOULD be copied into the
	into the PIDF-LO structure of the 'geolocation' header.		PIDF-LO structure of the 'geolocation' header field.
	4.3. Sending a Data-Only Emergency Call		4.3. Sending a Data-Only Emergency Call
	A data-only emergency call is sent using a SIP MESSAGE transaction		A data-only emergency call is sent using a SIP MESSAGE transaction
	with a CAP URI or body as described above in a manner similar to how		with a CAP URI or body as described above in a manner similar to how
	an emergency call with interactive media is sent, as described in		an emergency call with interactive media is sent, as described in
	[RFC6881]. The MESSAGE transaction does not create a session or send		[RFC6881]. The MESSAGE transaction does not create a session nor
	media, but otherwise, the header content of the transaction, routing,		send media, but otherwise, the header content of the transaction,
	and processing of data-only calls are the same as those of other		routing, and processing of data-only calls are the same as those of
	emergency calls.		other emergency calls.
	5. Error Handling		5. Error Handling
	This section defines a new error response code and a header field for		This section defines a new error response code and a header field for
	additional information.		additional information.
	5.1. 425 (Bad Alert Message) Response Code		5.1. 425 (Bad Alert Message) Response Code
	This SIP extension creates a new location-specific response code,		This SIP extension creates a new location-specific response code,
	defined as follows,		defined as follows:
	425 (Bad Alert Message)		425 (Bad Alert Message)
	The 425 response code is a rejection of the request due to its		The 425 response code is a rejection of the request due to its
	included alert content, indicating that it was malformed or not		included alert content, indicating that it was malformed or not
	satisfactory for the recipient's purpose.		satisfactory for the recipient's purpose.
	A SIP intermediary can also reject an alert it receives from a UA		A SIP intermediary can also reject an alert it receives from a UA
	when it understands that the provided alert is malformed.		when it understands that the provided alert is malformed.
	Section 5.2 describes an AlertMsg-Error header field with more		Section 5.2 describes an AlertMsg-Error header field with more
	details about what was wrong with the alert message in the request.		details about what was wrong with the alert message in the request.
	This header field MUST be included in the 425 response.		This header field MUST be included in the 425 response.
	It is only appropriate to generate a 425 response when the responding		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		entity has no other information in the request that is usable by the
	responder.		responder.
	A 425 response code MUST NOT be sent in response to a request that		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		lacks an alert message, as the user agent in that case may not
	not support this extension at all.		support this extension.
	A 425 response is a final response within a transaction, and MUST NOT		A 425 response is a final response within a transaction, and MUST NOT
	terminate an existing dialog.		terminate an existing dialog.
	5.2. The AlertMsg-Error Header Field		5.2. The AlertMsg-Error Header Field
	The AlertMsg-Error header provides additional information about what		The AlertMsg-Error header field provides additional information about
	was wrong with the original request. In some cases the provided		what was wrong with the original request. In some cases the provided
	information will be used for debugging purposes.		information will be used for debugging purposes.
	The AlertMsg-Error header field has the following ABNF [RFC5234]:		The AlertMsg-Error header field has the following ABNF [RFC5234]:
	message-header /= AlertMsg-Error		message-header /= AlertMsg-Error
	; (message-header from 3261)		; (message-header from 3261)
	AlertMsg-Error = "AlertMsg-Error" HCOLON		AlertMsg-Error = "AlertMsg-Error" HCOLON
	ErrorValue		ErrorValue
	ErrorValue = error-code		ErrorValue = error-code
	*(SEMI error-params)		*(SEMI error-params)
	error-code = 1*3DIGIT		error-code = 1*3DIGIT
	error-params = error-code-text		error-params = error-code-text
	/ generic-param ; from RFC3261		/ generic-param ; from RFC3261
	error-code-text = "code" EQUAL quoted-string ; from RFC3261		error-code-text = "code" EQUAL quoted-string ; from RFC3261
	HCOLON, SEMI, and EQUAL are defined in RFC3261 [RFC3261]. DIGIT is		HCOLON, SEMI, and EQUAL are defined in RFC3261 [RFC3261]. DIGIT is
	defined in RFC5234 [RFC5234].		defined in RFC5234 [RFC5234].
	The AlertMsg-Error header field MUST contain only one ErrorValue to		The AlertMsg-Error header field MUST contain only one ErrorValue to
	indicate what was wrong with the alert payload the recipient		indicate what was wrong with the alert payload the recipient
	determined was bad.		determined was bad.
	The ErrorValue contains a 3-digit error code indicating what was		The ErrorValue contains a 3-digit error code indicating what was
	wrong with the alert in the request. This error code has a		wrong with the alert in the request. This error code has a
	corresponding quoted error text string that is human understandable.		corresponding quoted error text string that is human understandable.
	The text string are OPTIONAL, but RECOMMENDED for human readability,		The text string are OPTIONAL, but RECOMMENDED for human readability,
	similar to the string phrase used for SIP response codes. That said,		similar to the string phrase used for SIP response codes. That said,
	the strings are complete enough for rendering to the user, if so		the strings are complete enough for rendering to the user, if so
	desired. The strings in this document are recommendations, and are		desired. The strings in this document are recommendations, and are
	not standardized - meaning an operator can change the strings - but		not standardized -- meaning an operator can change the strings -- but
	MUST NOT change the meaning of the error code. Similar to how RFC		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		3261 specifies, there MUST NOT be more than one string per error
	code.		code.
	The AlertMsg-Error header field MAY be included in any response as an		The AlertMsg-Error header field MAY be included in any response if an
	alert message was in the request part of the same transaction. For		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		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		can accept this MESSAGE, thus creating a dialog, even though its UA
	determined the alert message contained in the MESSAGE was bad. The		determined that the alert message contained in the MESSAGE was bad.
	PSAP merely includes an AlertMsg-Error header value in the 200 OK to		The PSAP merely includes an AlertMsg-Error header field value in the
	the MESSAGE informing the UA that the MESSAGE was accepted but the		200 OK to the MESSAGE, thus informing the UA that the MESSAGE was
	alert provided was bad.		accepted but the alert provided was bad.
	If, on the other hand, the PSAP cannot accept the transaction without		If, on the other hand, the PSAP cannot accept the transaction without
	a suitable alert message, a 425 response is sent.		a suitable alert message, a 425 response is sent.
	A SIP intermediary that requires the UA's alert message in order to		A SIP intermediary that requires the UA's alert message in order to
	properly process the transaction may also sends a 425 with a		properly process the transaction may also sends a 425 with an
	AlertMsg-Error code.		AlertMsg-Error code.
	This document defines an initial list of error code ranges for any		This document defines an initial list of AlertMsg-Error values for
	SIP response, including provisional responses (other than 100 Trying)		any SIP response, including provisional responses (other than 100
	and the new 425 response. There MUST be no more than one AlertMsg-		Trying) and the new 425 response. There MUST be no more than one
	Error code in a SIP response.		AlertMsg-Error code in a SIP response.
	AlertMsg-Error: 100 ; code="Cannot Process the Alert Payload"		AlertMsg-Error: 100 ; code="Cannot Process the Alert Payload"
	AlertMsg-Error: 101 ; code="Alert Payload was not present or could		AlertMsg-Error: 101 ; code="Alert Payload was not present or could
	not be found"		not be found"
	AlertMsg-Error: 102 ; code="Not enough information to determine the		AlertMsg-Error: 102 ; code="Not enough information to determine the
	purpose of the alert"		purpose of the alert"
	AlertMsg-Error: 103 ; code="Alert Payload was corrupted"		AlertMsg-Error: 103 ; code="Alert Payload was corrupted"
	Additionally, if an entity cannot or chooses not to process the alert		Additionally, if an entity cannot or chooses not to process the alert
	message from a SIP request, a 500 (Server Internal Error) SHOULD be		message from a SIP request, a 500 (Server Internal Error) SHOULD be
	used with or without a configurable Retry-After header field.		used with or without a configurable Retry-After header field.
	6. Updates to the CAP Message		6. Updates to the CAP Message
	If the sender anticipates that the content of the CAP message may		If the sender anticipates that the content of the CAP message may
	need to be updated during the lifecycle of the event referred to in		need to be updated during the lifecycle of the event referred to in
	the message, it may include an update block as defined in		the message, it may include an update block as defined in
	[I-D.rosen-ecrit-addldata-subnot].		[I-D.rosen-ecrit-addldata-subnot].If the sender includes an update
			block and does not have a globally reachable URI, then the UA must
			register it's contact with a Registrar, and include a GRUU in in the
			update block
	7. Call Backs		7. Call Backs
	This document does not describe any method for the recipient to call		This document does not describe any method for the recipient to call
	back the sender of the data-only call. Usually, these alerts are		back the sender of a data-only call. Usually, these alerts are sent
	sent by automata, and do not have any mechanism to receive calls of		by automata, which do not have a mechanism to receive calls of any
	any kind. The identifier in the From header may be useful to obtain		kind. The identifier in the 'From' header field may be useful to
	more information, but any such mechanism is not defined in this		obtain more information, but any such mechanism is not defined in
	document. The CAP message may contain related contact information		this document. The CAP message may contain related contact
	for the sender.		information for the sender.
	8. Handling Large Amounts of Data		8. Handling Large Amounts of Data
	It is not atypical for sensor to have large quantities of data that		It is not atypical for sensors to have large quantities of data that
	they may wish to send. Including large amounts of data in a MESSAGE		they may wish to send. Including large amounts of data in a MESSAGE
	is not advisable, because SIP entities are usually not equipped to		is not advisable, because SIP entities are usually not equipped to
	handle very large messages. In such cases, the sender SHOULD make		handle very large messages. In such cases, the sender SHOULD make
	use of the by-reference mechanisms defined for Additional Data which		use of the by-reference mechanisms defined in
	involve sending a URI in the Call-Info header and using HTTPS to		[I-D.ietf-ecrit-additional-data], which involves making the data
	retrieve the data. The CAP message itself can be sent by-reference		available via HTTPS (either at the originator or at another entity),
	using this mechanism as well as any or all of the Additional Data		placing a URI to the data in the 'Call-Info' header field, and the
	blocks that may contain sensor-specific data.		recipient using HTTPS to retrieve the data. The CAP message itself
			can be sent by-reference using this mechanism, as well as any or all
			of the Additional Data blocks that may contain sensor-specific data.
	9. Example		9. Example
	Figure 3 shows a CAP document indicating a BURGLARY alert issued by a		Figure 3 shows a CAP document indicating a BURGLARY alert issued by a
	sensor called 'sensor1@domain.com'. The location of the sensor can		sensor called 'sensor1@domain.com'. The location of the sensor can
	be obtained from the attached location information provided via the		be obtained from the attached location information provided via the
	'geolocation' header contained in the SIP MESSAGE structure.		'geolocation' header field contained in the SIP MESSAGE structure.
	Additionally, the sensor provided some data long with the alert		Additionally, the sensor provided some data along with the alert
	message using proprietary information elements only to be processed		message, using proprietary information elements intended only to be
	by the receiver, a SIP entity acting as an aggregator. This example		processed by the receiver, a SIP entity acting as an aggregator.
	reflects the description in Figure 1.		This example reflects the description in Figure 1.
	MESSAGE sip:aggregator@domain.com SIP/2.0		MESSAGE sip:aggregator@domain.com SIP/2.0
	Via: SIP/2.0/TCP sensor1.domain.com;branch=z9hG4bK776sgdkse		Via: SIP/2.0/TCP sensor1.domain.com;branch=z9hG4bK776sgdkse
	Max-Forwards: 70		Max-Forwards: 70
	From: sip:sensor1@domain.com;tag=49583		From: sip:sensor1@domain.com;tag=49583
	To: sip:aggregator@domain.com		To: sip:aggregator@domain.com
	Call-ID: asd88asd77a@1.2.3.4		Call-ID: asd88asd77a@1.2.3.4
	Geolocation: <cid:abcdef@domain.com>		Geolocation: <cid:abcdef@domain.com>
	;routing-allowed=yes		;routing-allowed=yes
	Supported: geolocation		Supported: geolocation
	Accept: application/pidf+xml, application/emergencyCall.cap+xml		Accept: application/pidf+xml, application/emergencyCall.cap+xml
	CSeq: 1 MESSAGE		CSeq: 1 MESSAGE
	Call-Info: cid:abcdef2@domain.com;purpose=emergencyCall.cap		Call-Info: cid:abcdef2@domain.com;purpose=emergencyCall.cap
	Content-Type: multipart/mixed; boundary=boundary1		Content-Type: multipart/mixed; boundary=boundary1
	Content-Length: ...		Content-Length: ...
	--boundary1		--boundary1
	Content-Type: application/emergencyCall.cap		Content-Type: application/emergencyCall.cap+xml
	Content-ID: <abcdef2@domain.com>		Content-ID: <abcdef2@domain.com>
	Content-Disposition: by-reference;handling=optional		Content-Disposition: by-reference;handling=optional
	<?xml version="1.0" encoding="UTF-8"?>		<?xml version="1.0" encoding="UTF-8"?>
	<alert xmlns="urn:oasis:names:tc:emergency:cap:1.1">		<alert xmlns="urn:oasis:names:tc:emergency:cap:1.1">
	<identifier>S-1</identifier>		<identifier>S-1</identifier>
	<sender>sip:sensor1@domain.com</sender>		<sender>sip:sensor1@domain.com</sender>
	<sent>2008-11-19T14:57:00-07:00</sent>		<sent>2008-11-19T14:57:00-07:00</sent>
	<status>Actual</status>		<status>Actual</status>
	<msgType>Alert</msgType>		<msgType>Alert</msgType>
	skipping to change at page 15, line 42 ¶		skipping to change at page 15, line 47 ¶
	Figure 4: Example Message conveying an Alert to a PSAP		Figure 4: Example Message conveying an Alert to a PSAP
	10. Security Considerations		10. Security Considerations
	This section discusses security considerations when SIP user agents		This section discusses security considerations when SIP user agents
	issue emergency alerts utilizing MESSAGE and CAP. Location specific		issue emergency alerts utilizing MESSAGE and CAP. Location specific
	threats are not unique to this document and are discussed in		threats are not unique to this document and are discussed in
	[RFC7378] and [RFC6442].		[RFC7378] and [RFC6442].
	The ECRIT emergency services architecture [RFC6443] considers		The ECRIT emergency services architecture [RFC6443] considers classic
	classical individual-to-authority emergency calling and the identity		individual-to-authority emergency calling where the identity of the
	of the emergency caller does not play a role at the time of the call		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		establishment itself, i.e., a response to the emergency call does not
	depend on the identity of the caller. In case of emergency alerts		depend on the identity of the caller. In the case of emergency
	generated by devices, like sensors, the processing may be different		alerts generated by devices such as sensors, the processing may be
	in order to reduce the number of falsely generated emergency alerts.		different in order to reduce the number of falsely generated
	Alerts may get triggered based on certain sensor input that may have		emergency alerts. Alerts may get triggered based on certain sensor
	been caused by other factors than the actual occurrence of an alert		input that may have been caused by factors other than the actual
	relevant event. For example, a sensor may simply be malfunctioning.		occurrence of an alert relevant event. For example, a sensor may
			simply be malfunctioning. For this reason, not all alert messages
	For this purpose not all alert messages are directly sent to a PSAP		are directly sent to a PSAP, but rather may be pre-processed by a
	but rather may be pre-processed by a separate entity, potentially		separate entity, potentially under supervision by a human, to filter
	under supervision by a human, to filter alerts and potentially		alerts and potentially correlate received alerts with others to
	correlate received alerts with others to obtain a larger picture of		obtain a larger picture of the ongoing situation.
	the ongoing situation.
	In any case, for alerts that are initiated by sensors the identity		In any case, for alerts initiated by sensors, the identity may play
	may play an important role in deciding whether to accept or ignore an		an important role in deciding whether to accept or ignore an incoming
	incoming alert message. With the scenario shown in Figure 1 it is		alert message. With the scenario shown in Figure 1 it is very likely
	very likely that only authorized sensor input will be processed. For		that only authorized sensor input will be processed. For this
	this purpose it needs to be ensured that no alert messages from an		reason, it needs to be possible to refuse to accept alert messages
	unknown origin are accepted. Two types of information elements can		from an unknown origin. Two types of information elements can be
	be used for this purpose:		used for this purpose:
	1. SIP itself provides security mechanisms that allow the		1. SIP itself provides security mechanisms that allow the
	verification of the originator's identity. These mechanisms can		verification of the originator's identity. These mechanisms can
	be re-used, such as P-Asserted-Identity [RFC3325] or SIP Identity		be re-used, such as P-Asserted-Identity [RFC3325] or SIP Identity
	[RFC4474]. The latter provides a cryptographic assurance while		[RFC4474]. The latter provides a cryptographic assurance while
	the former relies on a chain of trust model.		the former relies on a chain of trust model.
	2. CAP provides additional security mechanisms and the ability to		2. CAP provides additional security mechanisms and the ability to
	carry additional information about the sender's identity.		carry further information about the sender's identity.
	Section 3.3.2.1 of [cap] specifies the signing algorithms of CAP		Section 3.3.2.1 of [cap] specifies the signing algorithms of CAP
	documents.		documents.
	In addition to the desire to perform identity-based access control		In addition to the desire to perform identity-based access control,
	the classical communication security threats need to be considered,		the classic communication security threats need to be considered,
	including integrity protection to prevent forgery and replay of alert		including integrity protection to prevent forgery or replay of alert
	messages in transit. To deal with replay of alerts a CAP document		messages in transit. To deal with replay of alerts, a CAP document
	contains the mandatory <identifier>, <sender>, <sent> elements and an		contains the mandatory <identifier>, <sender>, <sent> elements and an
	optional <expire> element. These attributes make the CAP document		optional <expire> element. Together, these elements make the CAP
	unique for a specific sender and provide time restrictions. An		document unique for a specific sender and provide time restrictions.
	entity that has received a CAP message already within the indicated		An entity that has already received a CAP message within the
	timeframe is able to detect a replayed message and, if the content of		indicated timeframe is able to detect a replayed message and, if the
	that message is unchanged, then no additional security vulnerability		content of that message is unchanged, then no additional security
	is created. Additionally, it is RECOMMENDED to make use of SIP		vulnerability is created. Additionally, it is RECOMMENDED to make
	security mechanisms, such as SIP Identity [RFC4474], to tie the CAP		use of SIP security mechanisms, such as SIP Identity [RFC4474], to
	message to the SIP message. To provide protection of the entire SIP		tie the CAP message to the SIP message. To provide protection of the
	message exchange between neighboring SIP entities the usage of TLS is		entire SIP message exchange between neighboring SIP entities, the
	mandatory.		usage of TLS is MANDATORY.
	Note that none of the security mechanism in this document protect		Note that none of the security mechanism in this document protect
	against a compromised sensor sending crafted alerts.		against a compromised sensor sending crafted alerts.
	11. IANA Considerations		11. IANA Considerations
	11.1. Registration of the 'application/emergencyCall.cap+xml' MIME type		11.1. Registration of the 'application/emergencyCall.cap+xml' MIME type
	To: ietf-types@iana.org		To: ietf-types@iana.org
	skipping to change at page 17, line 28 ¶		skipping to change at page 17, line 28 ¶
	Required parameters: (none)		Required parameters: (none)
	Optional parameters: charset; Indicates the character encoding of		Optional parameters: charset; Indicates the character encoding of
	enclosed XML. Default is UTF-8 [RFC3629].		enclosed XML. Default is UTF-8 [RFC3629].
	Encoding considerations: Uses XML, which can employ 8-bit		Encoding considerations: Uses XML, which can employ 8-bit
	characters, depending on the character encoding used. See RFC		characters, depending on the character encoding used. See RFC
	3023 [RFC3023], Section 3.2.		3023 [RFC3023], Section 3.2.
	Security considerations: This content type is designed to carry		Security considerations: This content type is designed to carry
	payloads of the Common Alerting Protocol (CAP).		payloads of the Common Alerting Protocol (CAP). RFC XXX [Replace
			by the RFC number of this specification] discusses security
			considerations for this.
	Interoperability considerations: This content type provides a way to		Interoperability considerations: This content type provides a way to
	convey CAP payloads.		convey CAP payloads.
	Published specification: RFC XXX [Replace by the RFC number of this		Published specification: RFC XXX [Replace by the RFC number of this
	specification].		specification].
	Applications which use this media type: Applications that convey		Applications which use this media type: Applications that convey
	alerts and warnings according to the CAP standard.		alerts and warnings according to the CAP standard.
	Additional information: OASIS has published the Common Alerting		Additional information: OASIS has published the Common Alerting
	Protocol at http://www.oasis-open.org/committees/		Protocol at http://www.oasis-open.org/committees/
	documents.php&wg_abbrev=emergency		documents.php&wg_abbrev=emergency
	Person and email address to contact for further information: Hannes		Person and email address to contact for further information: Hannes
	Tschofenig, Hannes.Tschofenig@nsn.com		Tschofenig, hannes.tschofenig@gmx.net
	Intended usage: Limited use		Intended usage: Limited use
	Author/Change controller: IETF ECRIT working group		Author/Change controller: IETF ECRIT working group
	Other information: This media type is a specialization of		Other information: This media type is a specialization of
	application/xml RFC 3023 [RFC3023], and many of the considerations		application/xml RFC 3023 [RFC3023], and many of the considerations
	described there also apply to application/cap+xml.		described there also apply to application/cap+xml.
	11.2. IANA Registration of Additional Data Block		11.2. IANA Registration of 'cap' Additional Data Block
	This document registers a new block type in the sub-registry called		This document registers a new block type in the sub-registry called
	'Additional Data Blocks' defined in [I-D.ietf-ecrit-additional-data].		'Additional Data Blocks' defined in [I-D.ietf-ecrit-additional-data].
	The token is "cap" and the reference is this document.		The token is "cap" and the reference is this document.
	11.3. IANA Registration for 425 Response Code		11.3. IANA Registration for 425 Response Code
	In the SIP Response Codes registry, the following is added		In the SIP Response Codes registry, the following is added
	Reference: RFC-XXXX (i.e., this document)		Reference: RFC-XXXX (i.e., this document)
	skipping to change at page 19, line 8 ¶		skipping to change at page 19, line 8 ¶
	Response Code Reference		Response Code Reference
	------------------------------------------ ---------		------------------------------------------ ---------
	Request Failure 4xx		Request Failure 4xx
	425 Bad Alert Message [this doc]		425 Bad Alert Message [this doc]
	This SIP Response code is defined in Section 5.		This SIP Response code is defined in Section 5.
	11.4. IANA Registration of New AlertMsg-Error Header Field		11.4. IANA Registration of New AlertMsg-Error Header Field
	The SIP AlertMsg-error header field is created by this document, with		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-		its definition and rules in Section 5, to be added to the IANA
	parameters registry with two actions:		Session Initiation Protocol (SIP) Parameters registry with two
			actions:
	1. Update the Header Fields registry with		1. Update the Header Fields registry with
	Registry:		Registry:
	Header Name compact Reference		Header Name compact Reference
	----------------- ------- ---------		----------------- ------- ---------
	AlertMsg-Error [this doc]		AlertMsg-Error [this doc]
	2. In the portion titled "Header Field Parameters and Parameter		2. In the portion titled "Header Field Parameters and Parameter
	Values", add		Values", add
	Predefined		Predefined
	Header Field Parameter Name Values Reference		Header Field Parameter Name Values Reference
	----------------- ------------------- ---------- ---------		----------------- ------------------- ---------- ---------
	AlertMsg-Error code yes [this doc]		AlertMsg-Error code yes [this doc]
	11.5. IANA Registration for the SIP AlertMsg-Error Codes		11.5. IANA Registration for the SIP AlertMsg-Error Codes
	This document creates a new registry for SIP, called "AlertMsg-Error		This document creates a new registry for SIP, called "AlertMsg-Error
	Codes". AlertMsg-Error codes provide reason for the error discovered		Codes". AlertMsg-Error codes provide reasons for an error discovered
	by recipients, categorized by action to be taken by error recipient.		by a recipient, categorized by the action to be taken by the error
	The initial values for this registry are shown below.		recipient. The initial values for this registry are shown below.
	Registry Name: AlertMsg-Error Codes		Registry Name: AlertMsg-Error Codes
	Reference: [this doc]		Reference: [this doc]
	Registration Procedures: Specification Required		Registration Procedures: Specification Required
	Code Default Reason Phrase Reference		Code Default Reason Phrase Reference
	---- --------------------------------------------------- ---------		---- --------------------------------------------------- ---------
	100 "Cannot Process the Alert Payload" [this doc]		100 "Cannot Process the Alert Payload" [this doc]
	skipping to change at page 21, line 7 ¶		skipping to change at page 21, line 7 ¶
	<http://www.rfc-editor.org/info/rfc2392>.		<http://www.rfc-editor.org/info/rfc2392>.
	[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,		[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
	A., Peterson, J., Sparks, R., Handley, M., and E.		A., Peterson, J., Sparks, R., Handley, M., and E.
	Schooler, "SIP: Session Initiation Protocol", RFC 3261,		Schooler, "SIP: Session Initiation Protocol", RFC 3261,
	DOI 10.17487/RFC3261, June 2002,		DOI 10.17487/RFC3261, June 2002,
	<http://www.rfc-editor.org/info/rfc3261>.		<http://www.rfc-editor.org/info/rfc3261>.
	[RFC3428] Campbell, B., Ed., Rosenberg, J., Schulzrinne, H.,		[RFC3428] Campbell, B., Ed., Rosenberg, J., Schulzrinne, H.,
	Huitema, C., and D. Gurle, "Session Initiation Protocol		Huitema, C., and D. Gurle, "Session Initiation Protocol
	(SIP) Extension for Instant Messaging", RFC 3428, DOI		(SIP) Extension for Instant Messaging", RFC 3428,
	10.17487/RFC3428, December 2002,		DOI 10.17487/RFC3428, December 2002,
	<http://www.rfc-editor.org/info/rfc3428>.		<http://www.rfc-editor.org/info/rfc3428>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/		Specifications: ABNF", STD 68, RFC 5234,
	RFC5234, January 2008,		DOI 10.17487/RFC5234, January 2008,
	<http://www.rfc-editor.org/info/rfc5234>.		<http://www.rfc-editor.org/info/rfc5234>.
	[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media		[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
	Types", RFC 3023, DOI 10.17487/RFC3023, January 2001,		Types", RFC 3023, DOI 10.17487/RFC3023, January 2001,
	<http://www.rfc-editor.org/info/rfc3023>.		<http://www.rfc-editor.org/info/rfc3023>.
	[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO		[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
	10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November		10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
	2003, <http://www.rfc-editor.org/info/rfc3629>.		2003, <http://www.rfc-editor.org/info/rfc3629>.
	[RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance		[RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance
	for the Session Initiation Protocol", RFC 6442, DOI		for the Session Initiation Protocol", RFC 6442,
	10.17487/RFC6442, December 2011,		DOI 10.17487/RFC6442, December 2011,
	<http://www.rfc-editor.org/info/rfc6442>.		<http://www.rfc-editor.org/info/rfc6442>.
	[RFC6881] Rosen, B. and J. Polk, "Best Current Practice for		[RFC6881] Rosen, B. and J. Polk, "Best Current Practice for
	Communications Services in Support of Emergency Calling",		Communications Services in Support of Emergency Calling",
	BCP 181, RFC 6881, DOI 10.17487/RFC6881, March 2013,		BCP 181, RFC 6881, DOI 10.17487/RFC6881, March 2013,
	<http://www.rfc-editor.org/info/rfc6881>.		<http://www.rfc-editor.org/info/rfc6881>.
	[I-D.ietf-ecrit-additional-data]		[I-D.ietf-ecrit-additional-data]
	Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and		Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and
	J. Winterbottom, "Additional Data Related to an Emergency		J. Winterbottom, "Additional Data Related to an Emergency
	Call", draft-ietf-ecrit-additional-data-33 (work in		Call", draft-ietf-ecrit-additional-data-37 (work in
	progress), July 2015.		progress), October 2015.
	[I-D.rosen-ecrit-addldata-subnot]		[I-D.rosen-ecrit-addldata-subnot]
	Rosen, B., "Updating Additional Data related to an		Rosen, B., "Updating Additional Data related to an
	Emergency Call using Subscribe/ Notify", draft-rosen-		Emergency Call using Subscribe/ Notify", draft-rosen-
	ecrit-addldata-subnot-01 (work in progress), November		ecrit-addldata-subnot-01 (work in progress), November
	2013.		2013.
	13.2. Informative References		13.2. Informative References
	[RFC7378] Tschofenig, H., Schulzrinne, H., and B. Aboba, Ed.,		[RFC7378] Tschofenig, H., Schulzrinne, H., and B. Aboba, Ed.,
	"Trustworthy Location", RFC 7378, DOI 10.17487/RFC7378,		"Trustworthy Location", RFC 7378, DOI 10.17487/RFC7378,
	December 2014, <http://www.rfc-editor.org/info/rfc7378>.		December 2014, <http://www.rfc-editor.org/info/rfc7378>.
	[RFC4474] Peterson, J. and C. Jennings, "Enhancements for		[RFC4474] Peterson, J. and C. Jennings, "Enhancements for
	Authenticated Identity Management in the Session		Authenticated Identity Management in the Session
	Initiation Protocol (SIP)", RFC 4474, DOI 10.17487/		Initiation Protocol (SIP)", RFC 4474,
	RFC4474, August 2006,		DOI 10.17487/RFC4474, August 2006,
	<http://www.rfc-editor.org/info/rfc4474>.		<http://www.rfc-editor.org/info/rfc4474>.
	[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private		[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
	Extensions to the Session Initiation Protocol (SIP) for		Extensions to the Session Initiation Protocol (SIP) for
	Asserted Identity within Trusted Networks", RFC 3325, DOI		Asserted Identity within Trusted Networks", RFC 3325,
	10.17487/RFC3325, November 2002,		DOI 10.17487/RFC3325, November 2002,
	<http://www.rfc-editor.org/info/rfc3325>.		<http://www.rfc-editor.org/info/rfc3325>.
	[RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,		[RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
	"Framework for Emergency Calling Using Internet		"Framework for Emergency Calling Using Internet
	Multimedia", RFC 6443, DOI 10.17487/RFC6443, December		Multimedia", RFC 6443, DOI 10.17487/RFC6443, December
	2011, <http://www.rfc-editor.org/info/rfc6443>.		2011, <http://www.rfc-editor.org/info/rfc6443>.
	Authors' Addresses		Authors' Addresses
	Brian Rosen		Brian Rosen
	skipping to change at page 22, line 44 ¶		skipping to change at page 22, line 44 ¶
	Department of Computer Science		Department of Computer Science
	450 Computer Science Building		450 Computer Science Building
	New York, NY 10027		New York, NY 10027
	US		US
	Phone: +1 212 939 7004		Phone: +1 212 939 7004
	Email: hgs+ecrit@cs.columbia.edu		Email: hgs+ecrit@cs.columbia.edu
	URI: http://www.cs.columbia.edu		URI: http://www.cs.columbia.edu
	Hannes Tschofenig		Hannes Tschofenig
	Hall in Tirol 6060		ARM Limited
	Austria		Austria
	Email: Hannes.tschofenig@gmx.net		Email: Hannes.Tschofenig@gmx.net
	URI: http://www.tschofenig.priv.at		URI: http://www.tschofenig.priv.at
			Randall Gellens
			Email: rg+ietf@randy.pensive.org
End of changes. 68 change blocks.
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