draft-ietf-ecrit-requirements-01.txt		draft-ietf-ecrit-requirements-02.txt
	ecrit H. Schulzrinne		ecrit H. Schulzrinne
	Internet-Draft Columbia U.		Internet-Draft Columbia U.
	Expires: April 24, 2006 R. Marshall, Ed.		Expires: July 3, 2006 R. Marshall, Ed.
	TCS		TCS
	October 21, 2005		December 30, 2005
	Requirements for Emergency Context Resolution with Internet Technologies		Requirements for Emergency Context Resolution with Internet Technologies
	draft-ietf-ecrit-requirements-01.txt		draft-ietf-ecrit-requirements-02.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
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	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 35		skipping to change at page 1, line 35
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
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	This Internet-Draft will expire on April 24, 2006.		This Internet-Draft will expire on July 3, 2006.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2005).		Copyright (C) The Internet Society (2005).
	Abstract		Abstract
	This document enumerates requirements for emergency calls placed by		This document enumerates requirements for emergency calls placed by
	the public using voice-over-IP (VoIP) and general Internet multimedia		the public using voice-over-IP (VoIP) and general Internet multimedia
	systems, where Internet protocols are used end-to-end.		systems, where Internet protocols are used end-to-end.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
	3. Basic Actors . . . . . . . . . . . . . . . . . . . . . . . . . 7		3. Basic Actors . . . . . . . . . . . . . . . . . . . . . . . . . 8
	4. High-Level Requirements . . . . . . . . . . . . . . . . . . . 10		4. High-Level Requirements . . . . . . . . . . . . . . . . . . . 11
	5. Identifying the Caller Location . . . . . . . . . . . . . . . 12		5. Identifying the Caller Location . . . . . . . . . . . . . . . 13
	6. Emergency Identifier . . . . . . . . . . . . . . . . . . . . . 14		6. Emergency Identifier . . . . . . . . . . . . . . . . . . . . . 15
	7. Mapping Protocol . . . . . . . . . . . . . . . . . . . . . . . 16		7. Mapping Protocol . . . . . . . . . . . . . . . . . . . . . . . 17
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 20		8. Security Considerations . . . . . . . . . . . . . . . . . . . 22
	9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 21		9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 23
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22		10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23		11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
	11.1. Normative References . . . . . . . . . . . . . . . . . . 23		11.1. Normative References . . . . . . . . . . . . . . . . . . 25
	11.2. Informative References . . . . . . . . . . . . . . . . . 23		11.2. Informative References . . . . . . . . . . . . . . . . . 25
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26
	Intellectual Property and Copyright Statements . . . . . . . . . . 25		Intellectual Property and Copyright Statements . . . . . . . . . . 27
	1. Introduction		1. Introduction
	Users of both voice-centric (telephone-like) and non voice type		Users of both voice-centric (telephone-like) and non voice type
	services (e.g. text messaging for hearing disabled users, (RFC 3351		services (e.g. text messaging for hearing disabled users, (RFC 3351
	[4]) have an expectation to be able to initiate a request for help in		[5]) have an expectation to be able to initiate a request for help in
	case of an emergency.		case of an emergency.
	Unfortunately, the existing mechanisms to support emergency calls		Unfortunately, the existing mechanisms to support emergency calls
	that have evolved within the public circuit-switched telephone		that have evolved within the public circuit-switched telephone
	network (PSTN), are not appropriate to handle evolving IP-based		network (PSTN), are not appropriate to handle evolving IP-based
	voice, text and real-time multimedia communications. This document		voice, text and real-time multimedia communications. This document
	outlines the key requirements that IP-based end systems and network		outlines the key requirements that IP-based end systems and network
	elements, such as SIP proxies, need to satisfy in order to provide		elements, such as SIP proxies, need to satisfy in order to provide
	emergency call services, which at a minimum, offer the same		emergency call services, which at a minimum, offer the same
	functionality as existing PSTN services, with the additional overall		functionality as existing PSTN services, with the additional overall
	skipping to change at page 4, line 5		skipping to change at page 3, line 46
	Identification of the caller, while not incompatible with the		Identification of the caller, while not incompatible with the
	requirements for messaging outlined within this document, is not		requirements for messaging outlined within this document, is not
	currently considered within the scope of the ECRIT charter, and is		currently considered within the scope of the ECRIT charter, and is
	therefore, left for a future draft to describe.		therefore, left for a future draft to describe.
	Note: Location is required for two separate purposes, first, to route		Note: Location is required for two separate purposes, first, to route
	the call to the appropriate PSAP and second, to display the caller's		the call to the appropriate PSAP and second, to display the caller's
	location to the call taker for help in dispatching emergency		location to the call taker for help in dispatching emergency
	assistance to the correct location.		assistance to the correct location.
			Ideally, the mapping protocol would yield a URI from a preferred set
			of URIs (e.g. sips:uri; sip:uri), which would allow an emergency call
			to be completed using IP end-to-end (possibly via the Internet).
			Despite this goal, some PSAPs may not immediately have IP based
			connectivity, and therefore it is imperative that the URI scheme not
			be fixed, in order to ensure support for a less preferred set of
			URIs, such as a TEL URI which may be used to Complete a call over the
			PSTN.
	2. Terminology		2. Terminology
	In this document, the key words "MUST", "MUST NOT", "REQUIRED",		In this document, the key words "MUST", "MUST NOT", "REQUIRED",
	"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",		"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
	and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and		and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
	indicate requirement levels for compliant implementations.		indicate requirement levels for compliant implementations.
	Since a requirements document does not directly specify a protocol to		Since a requirements document does not directly specify a protocol to
	implement, these compliance labels should be read as indicating		implement, these compliance labels should be read as indicating
	requirements for the protocol or architecture, rather than an		requirements for the protocol or architecture, rather than an
	implementation.		implementation.
	For lack of a better term, we will use the term "caller" or		For lack of a better term, we will use the term "caller" or
	"emergency caller" to refer to the person placing an emergency call		"emergency caller" to refer to the person placing an emergency call
	or sending an emergency IM.		or sending an emergency IM.
	Application Service Provider (ASP): The organization or entity that		Application Service Provider (ASP): The organization or entity that
	provides application-layer services, which may include voice (see		provides application-layer services, which may include voice (see
	term Voice Service Provider). This entity can be a private		"Voice Service Provider"). This entity can be a private
	individual, an enterprise, a government, or a service provider.		individual, an enterprise, a government, or a service provider.
	An ASP is defined as something more general than a Voice Service		An ASP is defined as something more general than a Voice Service
	Provider, since emergency calls are sometimes likely to use other		Provider, since emergency calls are sometimes likely to use other
	media, including text and video. Note: For a particular user, the		media, including text and video. Note: For a particular user, the
	ASP may or may not be the same organization as the IAP and/or ISP.		ASP may or may not be the same organization as the IAP and/or ISP.
	Basic Emergency Service: Basic Emergency Service allows a user to		Basic Emergency Service: Basic Emergency Service allows a user to
	reach a PSAP serving its current location, but the PSAP may not be		reach a PSAP serving its current location, but the PSAP may not be
	able to determine the identity or geographic location of the		able to determine the identity or geographic location of the
	caller (except by having the call taker ask the caller).		caller (except by having the call taker ask the caller).
	skipping to change at page 4, line 45		skipping to change at page 5, line 45
	call taker: A call taker is an agent at the PSAP that accepts calls		call taker: A call taker is an agent at the PSAP that accepts calls
	and may dispatch emergency help. (Sometimes the functions of call		and may dispatch emergency help. (Sometimes the functions of call
	taking and dispatching are handled by different groups of people,		taking and dispatching are handled by different groups of people,
	but these divisions of labor are not generally visible to the		but these divisions of labor are not generally visible to the
	outside and thus do not concern us here.)		outside and thus do not concern us here.)
	civic location: A described location based on some defined grid, such		civic location: A described location based on some defined grid, such
	as a jurisdictional, postal, metropolitan, or rural reference		as a jurisdictional, postal, metropolitan, or rural reference
	system (e.g. street address).		system (e.g. street address).
	directory service: A network service which uses a distributed		mapping service: A network service which uses a distributed mapping
	directory protocol to provide information about the PSAP, or		protocol to provide information about the PSAP, or intermediary
	intermediary which knows about the PSAP, and is used to assist in		which knows about the PSAP, and is used to assist in routing an
	routing an emergency call.		emergency call.
	emergency address: The sip:uri, sips:uri, or tel:uri which represents		emergency address: The uri scheme (e.g. sip:uri, sips:uri, xmpp:uri,
	the address of the PSAP useful for the completion of an emergency		im:uri, etc.) which represents the address of the PSAP useful for
	call.		the completion of an emergency call.
	emergency caller: The user or user device entity which sends his/her		emergency caller: The user or user device entity which sends his/her
	location to another entity in the network.		location to another entity in the network.
	emergency identifier: The numerical and/or text identifier which is		emergency identifier: The numerical and/or text identifier which is
	supplied by a user or a user device, which identifies the call as		supplied by a user or a user device, which identifies the call as
	an emergency call and is translated into an emergency address for		an emergency call and is translated into an emergency address for
	call routing and completion.		call routing and completion.
	enhanced emergency service: Enhanced emergency services add the		enhanced emergency service: Enhanced emergency services add the
	skipping to change at page 5, line 31		skipping to change at page 6, line 31
	an individual.)		an individual.)
	ESRP (Emergency Services Routing Proxy): An ESRP is a call routing		ESRP (Emergency Services Routing Proxy): An ESRP is a call routing
	entity that invokes the location-to-URL mapping, which in turn may		entity that invokes the location-to-URL mapping, which in turn may
	return either the URL for another ESRP or the PSAP. (In a SIP		return either the URL for another ESRP or the PSAP. (In a SIP
	system, the ESRP would typically be a SIP proxy, but could also be		system, the ESRP would typically be a SIP proxy, but could also be
	a Back-to-back user agent (B2BUA).		a Back-to-back user agent (B2BUA).
	geographic location: A reference to a locatable point described by a		geographic location: A reference to a locatable point described by a
	set of defined coordinates within a geographic coordinate system,		set of defined coordinates within a geographic coordinate system,
	(e.g. lat/lon within WGS-84 datum)		(e.g. lat/lon within the WGS-84 datum)
	Internet Attachment Provider (IAP): An organization that provides		Internet Attachment Provider (IAP): An organization that provides
	physical network connectivity to its customers or users, e.g.		physical network connectivity to its customers or users, e.g.
	through digital subscriber lines, cable TV plants, Ethernet,		through digital subscriber lines, cable TV plants, Ethernet,
	leased lines or radio frequencies. This entity may or may not		leased lines or radio frequencies. Examples of such organizations
	also provide IP routing, IP addresses, or other Internet protocol		include telecommunication carriers, municipal utilities, larger
	services. Examples of such organizations include
	telecommunication carriers, municipal utilities, larger
	enterprises with their own network infrastructure, and government		enterprises with their own network infrastructure, and government
	organizations such as the military.		organizations such as the military.
	Internet Service Provider (ISP): An organization that provides IP		Internet Service Provider (ISP): An organization that provides IP
	network-layer services to its customers or users. This entity may		network-layer services to its customers or users. This entity may
	or may not provide the physical-layer and layer-2 connectivity,		or may not provide the physical-layer and layer-2 connectivity,
	such as fiber or Ethernet.		such as fiber or Ethernet.
			Local Emerency Identifier: An emergency identifier which is
			recognized from within a geographic or jurisdictional area from
			which an emergency request is initiated.
	location: A geographic identification assigned to a region or feature		location: A geographic identification assigned to a region or feature
	based on a specific coordinate system, or by other precise		based on a specific coordinate system, or by other precise
	information such as a street number and name. In the geocoding		information such as a street number and name. In the geocoding
	process, the location is defined with an x,y coordinate value		process, the location is defined with an x,y coordinate value
	according to the distance north or south of the equator and east		according to the distance north or south of the equator and east
	or west of the prime meridian.		or west of the prime meridian.
	location validation: A caller location is considered valid if the		location validation: A caller location is considered valid if the
	civic or geographic location is recognizable within an acceptable		civic or geographic location is recognizable within an acceptable
	location reference systems (e.g. USPS, WGS-84, etc.), and can be		location reference systems (e.g. USPS, WGS-84, etc.), and can be
	skipping to change at page 6, line 36		skipping to change at page 7, line 42
	PSAP (Public Safety Answering Point): Physical location where		PSAP (Public Safety Answering Point): Physical location where
	emergency calls are received under the responsibility of a public		emergency calls are received under the responsibility of a public
	authority. (This terminology is used by both ETSI, in ETSI SR 002		authority. (This terminology is used by both ETSI, in ETSI SR 002
	180, and NENA.) In the United Kingdom, PSAPs are called Operator		180, and NENA.) In the United Kingdom, PSAPs are called Operator
	Assistance Centres, in New Zealand, Communications Centres.		Assistance Centres, in New Zealand, Communications Centres.
	Within this document, it is assumed, unless stated otherwise, that		Within this document, it is assumed, unless stated otherwise, that
	PSAP is that which supports the receipt of emergency calls over		PSAP is that which supports the receipt of emergency calls over
	IP. It is also assumed that the PSAP is reachable by IP-based		IP. It is also assumed that the PSAP is reachable by IP-based
	protocols, such as SIP for call signaling and RTP for media.		protocols, such as SIP for call signaling and RTP for media.
			Universal Identifier: An emergency identifier which is recognized by
			any compatible endpoint, from any geographic location as useful
			for initiating an emergency request. A general approach to using
			universal identifiers is outlined in the service URN draft
			(I-D.schulzrinne-sipping-service [4]).
	Voice Service Provider (VSP): A specific type of Application Service		Voice Service Provider (VSP): A specific type of Application Service
	Provider which provides voice related services based on IP, such		Provider which provides voice related services based on IP, such
	as call routing, a SIP URI, or PSTN termination.		as call routing, a SIP URI, or PSTN termination.
	3. Basic Actors		3. Basic Actors
	In order to support emergency services covering a large physical area		In order to support emergency services covering a large physical area
	various infrastructure elements are necessary: Internet Attachment		various infrastructure elements are necessary: Internet Attachment
	Providers, Application/Voice Service Providers, PSAPs as endpoints		Providers, Application/Voice Service Providers, PSAPs as endpoints
	for emergency calls, directory services or other infrastructure		for emergency calls, mapping services or other infrastructure
	elements that assist in during the call routing and potentially many		elements that assist in during the call routing and potentially many
	other entities.		other entities.
	This section outlines which entities will be considered in the		This section outlines which entities will be considered in the
	routing scenarios discussed.		routing scenarios discussed.
	Location		Location
	Information +-----------------+		Information +-----------------+
	|(1) |Internet | +-----------+		|(1) |Internet | +-----------+
	v |Attachment | | |		v |Attachment | | |
	+-----------+ |Provider | | Directory |		+-----------+ |Provider | | Mapping |
	| | | (3) | | Service |		| | | (3) | | Service |
	| Emergency |<---+-----------------+-->| |		| Emergency |<---+-----------------+-->| |
	| Caller | | (2) | +-----------+		| Caller | | (2) | +-----------+
	| |<---+-------+ | ^		| |<---+-------+ | ^
	+-----------+ | +----|---------+------+ |		+-----------+ | +----|---------+------+ |
	^ | | Location | | |		^ | | Location | | |
	| | | Information<-+ | |		| | | Information<-+ | |
	| +--+--------------+ |(8) | | (5)		| +--+--------------+ |(8) | | (5)
	| | +-----------v+ | |		| | +-----------v+ | |
	| (4) | |Emergency | | |		| (4) | |Emergency | | |
	skipping to change at page 8, line 35		skipping to change at page 9, line 35
	Below, we describe various interactions between the entities shown in		Below, we describe various interactions between the entities shown in
	Figure 1 are described:		Figure 1 are described:
	o (1) Location information might be available to the end host itself.		o (1) Location information might be available to the end host itself.
	o (2) Location information might, however, also be obtained from the		o (2) Location information might, however, also be obtained from the
	Internet Attachment Provider (e.g., using DHCP or application layer		Internet Attachment Provider (e.g., using DHCP or application layer
	signaling protocols).		signaling protocols).
	o (3) The Emergency Caller might need to consult a directory service		o (3) The Emergency Caller might need to consult a mapping service to
	to determine the PSAP that is appropriate for the physical location		determine the PSAP that is appropriate for the physical location of
	of the emergency caller (and considering other attributes such as a		the emergency caller (and considering other attributes such as a
	certain language support by the Emergency Call Takers).		certain language support by the Emergency Call Takers).
	o (4) The Emergency Caller might get assistance for emergency call		o (4) The Emergency Caller might get assistance for emergency call
	routing by infrastructure elements (referred as Emergency Call		routing by infrastructure elements (referred as Emergency Call
	Routing Support entities). In case of SIP these entities are		Routing Support entities). In case of SIP these entities are
	proxies.		proxies.
	o (5) Individual Emergency Call Routing Support entities might need		o (5) Individual Emergency Call Routing Support entities might need
	to consult a directory servic to determine where to route the		to consult a mapping service to determine where to route the
	emergency call.		emergency call.
	o (6) The Emergency Call Routing Support entities need to finally		o (6) The Emergency Call Routing Support entities need to finally
	forward the call, if infrastructure based emergency call routing is		forward the call, if infrastructure based emergency call routing is
	used.		used.
	o (7) The emergency caller might interact directly with the PSAP		o (7) The emergency caller might interact directly with the PSAP
	without any Emergency Call Routing Support entities.		without any Emergency Call Routing Support entities.
			o (8) Location Information is used by emergency call routing entities
			to determine appropriate PSAP mapping.
	4. High-Level Requirements		4. High-Level Requirements
	Below, we summarize high-level architectural requirements that guide		Below, we summarize high-level architectural requirements that guide
	some of the component requirements detailed later in the document.		some of the component requirements detailed later in the document.
	Re1. Application Service Provider: The existence of an Application		Re1. Application Service Provider: The existence of an Application
	Service Provider (ASP) MUST NOT be assumed.		Service Provider (ASP) MUST NOT be assumed.
	Motivation: The caller may not have a application/voice service		Motivation: The caller may not have a application/voice service
	provider. For example, a residence may have its own DNS domain		provider. For example, a residence may have its own DNS domain
	skipping to change at page 10, line 47		skipping to change at page 11, line 47
	other regions or nations. The system cannot assume, for example,		other regions or nations. The system cannot assume, for example,
	that there is a single global entity issuing certificates for		that there is a single global entity issuing certificates for
	PSAPs, ASPs, IAPs or other participants.		PSAPs, ASPs, IAPs or other participants.
	Re4. Multiple Modes: Multiple communication modes, such as audio,		Re4. Multiple Modes: Multiple communication modes, such as audio,
	video and text messaging MUST be supported.		video and text messaging MUST be supported.
	Motivation: In PSTN, voice and text telephony (often called TTY or		Motivation: In PSTN, voice and text telephony (often called TTY or
	textphone in North America ) are the only commonly supported		textphone in North America ) are the only commonly supported
	media. Emergency calling must support a variety of media. Such		media. Emergency calling must support a variety of media. Such
	media should include voice, conversational text (RFC 4103 [6]),		media should include voice, conversational text (RFC 4103 [7]),
	instant messaging and video.		instant messaging and video.
	Re5. Alternate Mapping Sources: The mapping protocol SHOULD allow		Re5. Alternate Mapping Sources: The mapping protocol SHOULD allow
	for alternative redundant sources of mapping information, possibly		for alternative redundant sources of mapping information, possibly
	of different degrees of currency.		of different degrees of currency.
	Motivation: This provides the possibility of having available		Motivation: This provides the possibility of having available
	alternative sources of mapping information when the normal source		alternative sources of mapping information when the normal source
	is unavailable or unreachable, without specifying the means by		is unavailable or unreachable, without specifying the means by
	which the alternative source is created or updated.		which the alternative source is created or updated.
	skipping to change at page 11, line 26		skipping to change at page 12, line 26
	without special emergency extensions) unless an error is returned.		without special emergency extensions) unless an error is returned.
	Motivation: The format of the output returned by the mapping		Motivation: The format of the output returned by the mapping
	protocol is in a standard format for communication protocol. For		protocol is in a standard format for communication protocol. For
	example, it should return something SIP specific (e.g. URI), that		example, it should return something SIP specific (e.g. URI), that
	any SIP capable phone would be able to use if used in a SIP		any SIP capable phone would be able to use if used in a SIP
	context. Special purpose URIs would not be understood by "legacy"		context. Special purpose URIs would not be understood by "legacy"
	SIP devices since they do not have knowledge about the mapping		SIP devices since they do not have knowledge about the mapping
	protocol, and therefore are not to be used.		protocol, and therefore are not to be used.
	Re7. Relay Services: It SHOULD be possible to involve relay		Re7. Ubiquiteous Triggering: It MUST be possible to invoke the
	services in the call for translation between different modes.		mapping protocol at any time, from any location, by any client
			which supports the mapping protocol.
	Motivation: It should be possible to connect the relay service so		Motivation: While end devices are the typical initiators of
	that the direct flow of media to the emergency service is		mapping service requests, it is also expected that other mapping
	maintained. In addition, it should be possible to convey		clients, such as relays, 3rd party devices, PSAPs, etc. may also
	telemetry data, such as data from automobile crash sensors.		trigger a mapping request.
	Re8. PSAP Identification: The mapping information MUST be available		Re8. PSAP Identification: The mapping information MUST be available
	without having to enroll with a service provider.		without having to enroll with a service provider.
	Motivation: The mapping server may well be operated by a service		Motivation: The mapping server may well be operated by a service
	provider, but access to the server offering the mapping must not		provider, but access to the server offering the mapping must not
	require use of a specific ISP or VSP.		require use of a specific ISP or VSP.
	5. Identifying the Caller Location		5. Identifying the Caller Location
	skipping to change at page 12, line 25		skipping to change at page 13, line 25
	announcements (LLDP).		announcements (LLDP).
	UA-referenced: The caller's user agent provides a reference, via a		UA-referenced: The caller's user agent provides a reference, via a
	permanent or temporary identifier, to the location which is stored		permanent or temporary identifier, to the location which is stored
	by a location service somewhere else and then retrieved by the		by a location service somewhere else and then retrieved by the
	PSAP.		PSAP.
	Proxy-inserted: A proxy along the call path inserts the location or		Proxy-inserted: A proxy along the call path inserts the location or
	location reference.		location reference.
	Lo1. Validation of civic location: It MUST be possible to validate		Lo1. Validation of Civic Location: It MUST be possible to validate a
	an civic location prior to its use in an actual emergency call.		civic location prior to its use in an actual emergency call.
	Motivation: Location validation provides an opportunity to help		Motivation: Location validation provides an opportunity to help
	assure ahead of time, whether successful mapping to the		assure ahead of time, whether successful mapping to the
	appropriate PSAP will likely occur when it is required.		appropriate PSAP will likely occur when it is required.
	Validation may also help to avoid delays during emergency call		Validation may also help to avoid delays during emergency call
	setup due to invalid locations.		setup due to invalid locations.
	Lo2.: Validation of a civic location MUST NOT be required to enable		Lo2. Limits to Validation: Validation of a civic location MUST NOT
	any feature that is part of the emergency call process.		be required to enable any feature that is part of the emergency
			call process.
	Motivation: In some cases, (based on a variety of factors), a		Motivation: In some cases, (based on a variety of factors), a
	civic location may not be considered valid. This fact should not		civic location may not be considered valid. This fact should not
	result in the call being dropped or rejected by any entity along		result in the call being dropped or rejected by any entity along
	the signaling path to the PSAP.		the signaling path to the PSAP.
	Lo3. Reference Datum: The mapping server MUST understand WGS-84		Lo3. Reference Datum: The mapping server MUST understand WGS-84
	coordinate reference system and may understand other reference		coordinate reference system and may understand other reference
	systems.		systems.
	Lo4. Location Provided: An Emergency Services Routing Proxy (ESRP)		Lo4. Location Provided: An Emergency Services Routing Proxy (ESRP)
	MUST NOT remove location information after performing location		MUST NOT remove location information after performing location
	based routing.		based routing.
	Motivation: The ESRP and the PSAP use the same location		Motivation: The ESRP and the PSAP use the same location
	information object but for a different purpose. Therefore, the		information object but for a different purpose. Therefore, the
	PSAP still requires the receipt of information which represents		PSAP still requires the receipt of information which represents
	the end device's location.		the end device's location.
			Lo5. 3D Sensitive Mapping: The mapping protocol MUST accept either a
			2D or 3D mapping request, and return an appropriate result, based
			on which type of input is used.
			Motivation: It is expected that provisioning systems will accept
			both 2D and 3D data. When a 3D request is presented to an area
			only defined by 2D data, the mapping result would be the same as
			if the height/altitude dimension was omitted on the request."
	6. Emergency Identifier		6. Emergency Identifier
	Id1. Universal Identifier - Setup: One or more universal emergency		Id1. Universal Identifier Setup: One or more universal emergency
	identifiers MUST be recognized by any device or network element		identifiers MUST be recognized by any device or network element
	for call setup purposes		for call setup purposes
	Motivation: There must be some way for any device or element to		Motivation: There must be some way for any device or element to
	recognize an emergency call throughout the call setup. This is		recognize an emergency call throughout the call setup. This is
	regardless of the device location, the application (voice) service		regardless of the device location, the application (voice) service
	provider used (if any at all), or of any other factor. Examples		provider used (if any at all), or of any other factor. Examples
	of these might include: 911, 112, and sos.*.		of these might include: 911, 112, and sos.*.
	Id2. Universal Identifier Resolution: Where multiple emergency		Id2. Universal Identifier Resolution: Where multiple emergency
	skipping to change at page 14, line 29		skipping to change at page 15, line 29
	identifier separately, based on the specific type of emergency		identifier separately, based on the specific type of emergency
	help requested.		help requested.
	Motivation: Some jurisdictions may have multiple types of		Motivation: Some jurisdictions may have multiple types of
	emergency services available at the same level, (e.g. fire,		emergency services available at the same level, (e.g. fire,
	police, ambulance), in which case it is important that any one		police, ambulance), in which case it is important that any one
	could be selected directly.		could be selected directly.
	Id3. Emergency Marking: Any device in the signaling path that		Id3. Emergency Marking: Any device in the signaling path that
	recognizes by some means that the signaling is associated with an		recognizes by some means that the signaling is associated with an
	emergency call MUST add the emergency indication called for in A1a		emergency call MUST add the emergency indication called for in Id1
	to the signaling before forwarding it. This marking mechanism		to the signaling before forwarding it. This marking mechanism
	must be different than QoS marking.		must be different than QoS marking.
	Motivation: Marking ensures proper handling as an emergency call		Motivation: Marking ensures proper handling as an emergency call
	by downstream elements that may not recognize, for example, a		by downstream elements that may not recognize, for example, a
	local variant of a logical emergency address (see requirement		local variant of a logical emergency address.
	A4+).
	Id4. Emergency Identifier-based Marking: User agents, proxies, and		Id4. Emergency Identifier-based Marking: User agents, proxies, and
	other network elements that process signaling associated with		other network elements that process signaling associated with
	emergency calls SHOULD be configured to recognize a reasonable		emergency calls SHOULD be configured to recognize a reasonable
	selection of logical emergency identifiers (described in		selection of logical emergency identifiers as a means to initiate
	requirements below) as a means to initiate emergency marking.		emergency marking.
	Motivation: Since user devices roam, emergency identifiers may		Motivation: Since user devices roam, emergency identifiers may
	vary from region to region. It is therefore important that a		vary from region to region. It is therefore important that a
	network entity be able to perform mapping and/or call routing		network entity be able to perform mapping and/or call routing
	within the context of its own point of origin rather than relying		within the context of its own point of origin rather than relying
	on non-local logical emergency identifiers as the only basis for		on non-local logical emergency identifiers as the only basis for
	emergency marking of calls.		emergency marking of calls.
	Id5. Prevention of Fraud: A call identified as an emergency call or		Id5. Prevention of Fraud: A call identified as an emergency call or
	marked as such in accordance with the above requirements for		marked as such in accordance with the above requirements for
	skipping to change at page 16, line 5		skipping to change at page 16, line 34
	of an enterprise).		of an enterprise).
	Motivation: Any signalling protocol requires the use of some		Motivation: Any signalling protocol requires the use of some
	identifier to indicate the called party, and the user terminal may		identifier to indicate the called party, and the user terminal may
	lack the capability to determine the actual emergency address		lack the capability to determine the actual emergency address
	(PSAP uri). The use of local conventions may be required as a		(PSAP uri). The use of local conventions may be required as a
	transition mechanism. Note: Such use complicates international		transition mechanism. Note: Such use complicates international
	movement of the user terminal, and evolution to a standardized		movement of the user terminal, and evolution to a standardized
	universal emergency identifier or set of identifiers is preferred.		universal emergency identifier or set of identifiers is preferred.
			Id8. Universal Identifier Recognition: Universal identifier(s), MUST
			be universally recognizable by any network element which supports
			the ECRIT protocol."
			Id9. Universal Identifier not Recognized: A call MUST be recognized
			as emergency call even if the specific emergency service requested
			is not recognized."
			"Motivation: In order to have a robust system that supports
			incremental Service deployment while still maintaining a fallback
			capability."
	7. Mapping Protocol		7. Mapping Protocol
	Given the requirement from the previous section, that of a single (or		Given the requirement from the previous section, that of a single (or
	small number of) emergency identifier(s) which are independent of the		small number of) emergency identifier(s) which are independent of the
	caller's location, and since PSAPs only serve a limited geographic		caller's location, and since PSAPs only serve a limited geographic
	region, and for reasons of jurisdictional and local knowledge, having		region, and for reasons of jurisdictional and local knowledge, having
	the call reach the appropriate PSAP based on a mapping protocol, is		the call reach the appropriate PSAP based on a mapping protocol, is
	crucial.		crucial.
	There are two basic architectures described for translating an		There are two basic architectures described for translating an
	skipping to change at page 17, line 42		skipping to change at page 18, line 42
	limited caching mechanism should be supported.		limited caching mechanism should be supported.
	Ma4. Referral: The mapping client MUST be able to contact any server		Ma4. Referral: The mapping client MUST be able to contact any server
	and be referred to another server that is more qualified to answer		and be referred to another server that is more qualified to answer
	the query.		the query.
	Motivation: This requirement alleviates the potential for		Motivation: This requirement alleviates the potential for
	incorrect configurations to cause calls to fail, particularly for		incorrect configurations to cause calls to fail, particularly for
	caller-based queries.		caller-based queries.
	Ma5. The mapping protocol MUST allow a response to carry multiple		Ma5. Multiple Response URIs: The mapping protocol response MUST
	URIs.		allow the return of multiple URIs.
	Motivation: In response to a mapping request, a server will		Motivation: In response to a mapping request, a server will
	normally provide a URI or set of URIs for contacting the		normally provide a URI or set of URIs for contacting the
	appropriate PSAP.		appropriate PSAP.
	Ma6. The mapping protocol MUST be able to return a URI or contact		Ma6. URI - Alternate Contact: The mapping protocol MUST be able to
	method explicitly marked as an alternate contact.		return a URI or contact method explicitly marked as an alternate
			contact.
	Motivation: In response to a mapping request, if an expected URI		Motivation: In response to a mapping request, if an expected URI
	is unable to be returned, then mapping server may return an		is unable to be returned, then mapping server may return an
	alternate URI. When and how this would be used will be described		alternate URI. When and how this would be used will be described
	in an operational document.		in an operational document.
	Ma7. Multiple PSAP uri's: The mapping protocol MUST be able to		Ma7. Multiple PSAP URI's: The mapping protocol MUST be able to
	return multiple URLs for different PSAPs that cover the same area.		return multiple URIs for different PSAPs that cover the same area.
	Ma8. URL properties: The mapping protocol must provide additional		Ma8. URL properties: The mapping protocol must provide additional
	information that allows the querying entity to determine relevant		information that allows the querying entity to determine relevant
	properties of the URL.		properties of the URL.
	Motivation: In some cases, the same geographic area is served by		Motivation: In some cases, the same geographic area is served by
	several PSAPs, for example, a corporate campus might be served by		several PSAPs, for example, a corporate campus might be served by
	both a corporate security department and the municipal PSAP. The		both a corporate security department and the municipal PSAP. The
	mapping protocol should then return URLs for both, with		mapping protocol should then return URLs for both, with
	information allowing the querying entity to choose one or the		information allowing the querying entity to choose one or the
	skipping to change at page 19, line 25		skipping to change at page 20, line 25
	Ma14. Location Updates: It SHOULD be possible to have updates of		Ma14. Location Updates: It SHOULD be possible to have updates of
	location.		location.
	Motivation: Updated location information may have an impact on		Motivation: Updated location information may have an impact on
	PSAP routing. In some cases it may be possible to redirect that		PSAP routing. In some cases it may be possible to redirect that
	call to a more appropriate PSAP (some device measurement		call to a more appropriate PSAP (some device measurement
	techniques provide quick (i.e. early), but imprecise "first fix"		techniques provide quick (i.e. early), but imprecise "first fix"
	location).		location).
	Ma15. Extensible Protocol The mapping protocol MUST be extensible to		Ma15. Extensible Protocol: The mapping protocol MUST be extensible
	allow for the inclusion of new location fields.		to allow for the inclusion of new location fields.
	Motivation: This is needed, for example, to accommodate future		Motivation: This is needed, for example, to accommodate future
	extensions to location information that might be included in the		extensions to location information that might be included in the
	PIDF-LO (I-D.ietf-geopriv-pidf-lo-03 [2])		PIDF-LO (RFC 4119 [2]).
	Ma16. Split responsibility: The mapping protocol MUST allow that		Ma16. Split responsibility: The mapping protocol MUST allow that
	within a single level of the civic location hierarchy, multiple		within a single level of the civic location hierarchy, multiple
	mapping servers handle subsets of the data elements.		mapping servers handle subsets of the data elements.
	Motivation: For example, two directories for the same city or		Motivation: For example, two directories for the same city or
	county may handle different streets within that city or county.		county may handle different streets within that city or county.
	Ma17. The mapping function MUST be able to be invoked at any time,		Ma17. Pervasive Mapping: The mapping function MUST be able to be
	including while an emergency call is in process.		invoked at any time, including while an emergency call is in
			process.
	Ma18. Baseline query protocol: A mandatory-to-implement protocol		Ma18. Baseline query protocol: A mandatory-to-implement protocol
	MUST be specified.		MUST be specified.
	Motivation: An over-abundance of similarly-capable choices appears		Motivation: An over-abundance of similarly-capable choices appears
	undesirable for interoperability.		undesirable for interoperability.
			Ma19. Single URI Scheme: The mapping protocol MAY return multiple
			URIs, though it SHOULD return only one URI per scheme, so that
			clients are not required to select among different targets for the
			same contact protocol.
			Motivation: There may be two or more URIs returned when multiple
			contact protocols are available (e.g. SIP and SMS). The client
			may select among multiple contact protocols based on its
			capabilities, preference settings, or availability.
	8. Security Considerations		8. Security Considerations
	Note: Security Considerations are referenced in the ECRIT security		Note: Security Considerations are referenced in the ECRIT security
	document [3].		document [3].
	9. Contributors		9. Contributors
	The information contained in this document is a result of a joint		The information contained in this document is a result of a joint
	effort based on individual contributions by those involved in the		effort based on individual contributions by those involved in the
	ECRIT WG. The contributors include Nadine Abbott, Hideki Arai,		ECRIT WG. The contributors include Nadine Abbott, Hideki Arai,
	skipping to change at page 23, line 13		skipping to change at page 25, line 13
	their input.		their input.
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement		[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
	Levels", BCP 14, RFC 2119, March 1997.		Levels", BCP 14, RFC 2119, March 1997.
	[2] Peterson, J., "A Presence-based GEOPRIV Location Object Format",		[2] Peterson, J., "A Presence-based GEOPRIV Location Object Format",
	draft-ietf-geopriv-pidf-lo-03 (work in progress),		RFC 4119, December 2005.
	September 2004.
	[3] Tschofenig, H., "Security Threats and Requirements for Emergency		[3] Schulzrinne, H., "Security Threats and Requirements for
	Calling", draft-tschofenig-ecrit-security-threats-01 (work in		Emergency Calling", draft-taylor-ecrit-security-threats-01 (work
	progress), July 2005.		in progress), December 2005.
			[4] Schulzrinne, H., "A Uniform Resource Name (URN) for Services",
			draft-schulzrinne-sipping-service-01 (work in progress),
			October 2005.
	11.2. Informative References		11.2. Informative References
	[4] Charlton, N., Gasson, M., Gybels, G., Spanner, M., and A. van		[5] Charlton, N., Gasson, M., Gybels, G., Spanner, M., and A. van
	Wijk, "User Requirements for the Session Initiation Protocol		Wijk, "User Requirements for the Session Initiation Protocol
	(SIP) in Support of Deaf, Hard of Hearing and Speech-impaired		(SIP) in Support of Deaf, Hard of Hearing and Speech-impaired
	Individuals", RFC 3351, August 2002.		Individuals", RFC 3351, August 2002.
	[5] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.		[6] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.
	Polk, "Geopriv Requirements", RFC 3693, February 2004.		Polk, "Geopriv Requirements", RFC 3693, February 2004.
	[6] Hellstrom, G. and P. Jones, "RTP Payload for Text Conversation",		[7] Hellstrom, G. and P. Jones, "RTP Payload for Text Conversation",
	RFC 4103, June 2005.		RFC 4103, June 2005.
	[7] Wijk, A., "Framework of requirements for real-time text		[8] Wijk, A., "Framework of requirements for real-time text
	conversation using SIP", draft-ietf-sipping-toip-03 (work in		conversation using SIP", draft-ietf-sipping-toip-03 (work in
	progress), September 2005.		progress), September 2005.
	Authors' Addresses		Authors' Addresses
	Henning Schulzrinne		Henning Schulzrinne
	Columbia University		Columbia University
	Department of Computer Science		Department of Computer Science
	450 Computer Science Building		450 Computer Science Building
	New York, NY 10027		New York, NY 10027
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