draft-ietf-sipcore-status-unwanted-00.txt		draft-ietf-sipcore-status-unwanted-01.txt
	SIPCORE H. Schulzrinne		SIPCORE H. Schulzrinne
	Internet-Draft FCC		Internet-Draft FCC
	Intended status: Standards Track December 12, 2016		Intended status: Standards Track January 4, 2017
	Expires: June 15, 2017		Expires: July 8, 2017
	A SIP Response Code for Unwanted Calls		A SIP Response Code for Unwanted Calls
	draft-ietf-sipcore-status-unwanted-00		draft-ietf-sipcore-status-unwanted-01
	Abstract		Abstract
	This document defines the 666 (Unwanted) SIP response code, allowing		This document defines the 666 (Unwanted) SIP response code, allowing
	called parties to indicate that the call was unwanted. The		called parties to indicate that the call was unwanted. SIP entities
	terminating SIP entity may use this information to adjust future call		may use this information to adjust how future calls from this calling
	handling behavior for this called party or more broadly.		party are handled for the called party or more broadly.
	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.
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	This Internet-Draft will expire on June 15, 2017.		This Internet-Draft will expire on July 8, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2017 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
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	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
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	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Normative Language . . . . . . . . . . . . . . . . . . . . . 2		2. Normative Language . . . . . . . . . . . . . . . . . . . . . 2
	3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 2		3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 2
	4. Behavior of SIP Entities . . . . . . . . . . . . . . . . . . 3		4. Behavior of SIP Entities . . . . . . . . . . . . . . . . . . 3
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	5.1. SIP Response Code . . . . . . . . . . . . . . . . . . . . 3		5.1. SIP Response Code . . . . . . . . . . . . . . . . . . . . 4
	5.2. SIP Global Feature-Capability Indicator . . . . . . . . . 4		5.2. SIP Global Feature-Capability Indicator . . . . . . . . . 4
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 4		6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	8.1. Normative References . . . . . . . . . . . . . . . . . . 5		8.1. Normative References . . . . . . . . . . . . . . . . . . 5
	8.2. Informative References . . . . . . . . . . . . . . . . . 5		8.2. Informative References . . . . . . . . . . . . . . . . . 6
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	In many countries, an increasing number of calls are unwanted		In many countries, an increasing number of calls are unwanted
	[RFC5039], as they might be fraudulent, illegal telemarketing or the		[RFC5039]: they might be fraudulent, illegal telemarketing or the
	receiving party does not want to be disturbed by, say, surveys or		receiving party does not want to be disturbed by, say, surveys or
	solicitation by charities. Carriers and other service providers may		solicitation by charities. Carriers and other service providers may
	want to help their subscribers avoid receiving such calls, using a		want to help their subscribers avoid receiving such calls, using a
	variety of global or user-specific filtering algorithms. One input		variety of global or user-specific filtering algorithms. One input
	into such algorithms is user feedback. User feedback may be offered		into such algorithms is user feedback. User feedback may be offered
	through smartphone apps, APIs or within the context of a SIP-		through smartphone apps, APIs or within the context of a SIP-
	initiated call. This document addresses only the last mode, where		initiated call. This document addresses only the last mode, where
	the called party either rejects the SIP request, typically INVITE or		the called party either rejects the SIP [RFC3261] request, typically
	MESSAGE, as unwanted or terminates the call with a BYE request after		requests using the INVITE or MESSAGE methods, as unwanted or
	answering the call. To allow the called party to express that the		terminates the call with a BYE request after answering the call. To
	call was unwanted, this document defines the 666 (Unwanted) response		allow the called party to express that the call was unwanted, this
	code. The called party or a automata acting on her behalf uses this		document defines the 666 (Unwanted) response code. The called user
	to indicate that future calls from the same caller are also unwanted.		agent (UAS), based on input from the called party or some UA-internal
			logic, uses this to indicate that future calls from the same caller
			are also unwanted.
	2. Normative Language		2. Normative Language
	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 BCP 14, RFC 2119		document are to be interpreted as described in BCP 14, RFC 2119
	[RFC2119].		[RFC2119].
	3. Motivation		3. Motivation
	None of the existing 4xx, 5xx or 6xx response codes allow the called		None of the existing 4xx, 5xx or 6xx response codes signify that
	party to convey that they not only reject this call, e.g., using 480		calls from this caller are unwanted by the called party. The
	(Temporarily Unavailable), 486 (Busy Here), 600 (Busy Everywhere),		particular response code number was chosen to reflect the distaste
	603 (Decline) or 606 (Not Acceptable), but that the caller is		felt by many upon receiving such calls.
	unwanted. The particular response code number was chosen to reflect
	the distaste felt by many upon receiving such calls.
	4. Behavior of SIP Entities		4. Behavior of SIP Entities
	The response code MAY also be used in Reason header fields [RFC3326],		The response code 666 MAY be used in a failure response for an
	typically when the UAS issues a BYE request terminating an incoming		INVITE, MESSAGE, SUBSCRIBE or other out-of-dialog SIP request to
	call.		indicate that the offered communication is unwanted. The response
			code MAY also be used as the value of the "cause" parameter of a SIP
			reason-value in a Reason header field [RFC3326], typically when the
			UAS issues a BYE or CANCEL request terminating an incoming call.
	The SIP entities receiving this response code are not obligated to		The SIP entities receiving this response code are not obligated to
	take any particular action. The service provider delivering calls to		take any particular action. The service provider delivering calls to
	the user issuing the response may, for example, add the calling party		the user issuing the response, for example, MAY add the calling party
	to a personal blacklist specific to the called party, or may use the		to a personal blacklist specific to the called party, MAY use the
	information as input when computing the likelihood that the calling		information as input when computing the likelihood that the calling
	party is placing unwanted calls ("crowd sourcing"), might initiate a		party is placing unwanted calls ("crowd sourcing"), MAY initiate a
	traceback request, or could report the calling number to government		traceback request, and MAY report the calling number to government
	authorities. Receiving systems could decide to treat pre-call and		authorities.
	mid-call responses differently, given that the called party has had
	access to call content for mid-call rejections. In other words,		Receiving systems could decide to treat pre-call and mid-call
	depending on the implementation, the response code does not		responses differently, given that the called party has had access to
	necessarily automatically block all calls from that number. The same		call content for mid-call rejections. In other words, depending on
	user interface action might also trigger addition of the number to a		the implementation, the response code does not necessarily
			automatically block all calls from that number. The same user
			interface action might also trigger addition of the number to a
	local, on-device blacklist or graylist, e.g., causing such calls to		local, on-device blacklist or graylist, e.g., causing such calls to
	be flagged or alert with a different ring tone.		be flagged or alerted with a different ring tone.
			The actions described here do not depend on the nature of the SIP
			URI, e.g., whether it describes a telephone number or not; however,
			the same anonymous SIP URI [RFC3323] may be used by multiple callers
			and thus such URIs are unlikely to be appropriate for URI-specific
			call treatment. SIP entities tallying responses for particular
			callers may need to consider canonicalzing SIP URIs, including
			telephone numbers, as described in [I-D.ietf-stir-rfc4474bis].
	We define a SIP feature-capability [RFC6809], sip.666, that allows		We define a SIP feature-capability [RFC6809], sip.666, that allows
	the registrar to indicate that it supports this particular response		the registrar to indicate that the corresponding proxy supports this
	code. This allows the UA, for example, to provide a suitable user		particular response code. This allows the UA, for example, to
	interface element, such as a "spam" button, only if its service		provide a suitable user interface element, such as a "spam" button,
	provider actually supports the feature. The presence of the feature		only if its service provider actually supports the feature. The
	capability does not imply that the provider will take any particular		presence of the feature capability does not imply that the provider
	action, such as blocking future calls. A UA may still decide to		will take any particular action, such as blocking future calls. A UA
	render a "spam" button even without such as a capability if, for		may still decide to render a "spam" button even without such as a
	example, it maintains a device-local blacklist or reports unwanted		capability if, for example, it maintains a device-local blacklist or
	calls to a third party.		reports unwanted calls to a third party.
	5. IANA Considerations		5. IANA Considerations
	5.1. SIP Response Code		5.1. SIP Response Code
	This document register a new SIP response code. This response code		This document registers a new SIP response code. This response code
	is defined by the following information, which is to be added to the		is defined by the following information, which is to be added to the
	method and response-code sub-registry under		"Response Codes" sub-registry under http://www.iana.org/assignments/
	http://www.iana.org/assignments/sip-parameters.		sip-parameters.
	Response Code Number 666		Response Code Number 666
	Default Reason Phrase Unwanted		Default Reason Phrase Unwanted
	Reference [this RFC]		Reference [this RFC]
	5.2. SIP Global Feature-Capability Indicator		5.2. SIP Global Feature-Capability Indicator
	This document defines the feature capability sip.666 in the "SIP		This document defines the feature capability sip.666 in the "SIP
	Feature-Capability Indicator Registration Tree" registry defined in		Feature-Capability Indicator Registration Tree" registry defined in
	[RFC6809].		[RFC6809].
	Name sip.666		Name sip.666
	skipping to change at page 4, line 34 ¶		skipping to change at page 4, line 48 ¶
	from the legitimate user of the number in addition to the unwanted		from the legitimate user of the number in addition to the unwanted
	caller, i.e., creating a form of denial-of-service attack. Thus, the		caller, i.e., creating a form of denial-of-service attack. Thus, the
	response code SHOULD NOT be used for creating global call filters		response code SHOULD NOT be used for creating global call filters
	unless the calling party number has been authenticated using		unless the calling party number has been authenticated using
	[I-D.ietf-stir-rfc4474bis] as being assigned to the caller placing		[I-D.ietf-stir-rfc4474bis] as being assigned to the caller placing
	the unwanted call. (The creation of call filters local to a user		the unwanted call. (The creation of call filters local to a user
	agent is beyond the scope of this document.)		agent is beyond the scope of this document.)
	Even if the number is not spoofed, a call recipient might flag		Even if the number is not spoofed, a call recipient might flag
	legitimate numbers, e.g., to extract vengeance on a person or		legitimate numbers, e.g., to extract vengeance on a person or
	business, or simply by mistake. Thus, any additions to a personal		business, or simply by mistake. To correct errors, any additions to
	list of blocked numbers should be observable by the subscriber, e.g.,		a personal list of blocked numbers should be observable and
	on a web page or by regular email notification, and reservible. Any		reversible by the party being protected by the blacklist. For
	additions to a global or carrier-wide list of unwanted callers needs		example, the list may be shown on a web page or the subscriber may be
	to consider that any user-initiated mechanism will suffer from an		notified by periodic email reminders. Any additions to a global or
	unavoidable rate of false positives and tailor their algorithms		carrier-wide list of unwanted callers needs to consider that any
	accordingly, e.g., by comparing the fraction of delivered calls for a		user-initiated mechanism will suffer from an unavoidable rate of
	particular caller that are flagged as unwanted rather than just the		false positives and tailor their algorithms accordingly, e.g., by
	absolute number, and considering time-weighted filters that give more		comparing the fraction of delivered calls for a particular caller
	credence to recent feedback.		that are flagged as unwanted rather than just the absolute number,
			and considering time-weighted filters that give more credence to
			recent feedback.
	Since telephone numbers are routinely re-assigned to new subscribers,		Since telephone numbers are routinely re-assigned to new subscribers,
	algorithms are advised to consider whether the number has been re-		algorithms are advised to consider whether the number has been re-
	assigned to a new subscriber and possibly reset any related rating.		assigned to a new subscriber and possibly reset any related rating.
	For both individually-authenticated and unauthenticated calls,		For both individually-authenticated and unauthenticated calls,
	recipients may want to distinguish responses sent before and after		recipients may want to distinguish responses sent before and after
	the call has been answered, ascertaining whether either response		the call has been answered, ascertaining whether either response
	timing suffers from a lower false-positive rate.		timing suffers from a lower false-positive rate.
	7. Acknowledgements		7. Acknowledgements
	Martin Dolly, Keith Drage, Paul Kyzivat, Brian Rosen and Chris Wendt		Tolga Asveren, Peter Dawes, Martin Dolly, Keith Drage, Vijay Gurbani,
			Paul Kyzivat, Jean Mahoney, Brian Rosen, Chris Wendt and Dale Worley
	provided helpful comments.		provided helpful comments.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	skipping to change at page 5, line 46 ¶		skipping to change at page 6, line 13 ¶
	<http://www.rfc-editor.org/info/rfc6809>.		<http://www.rfc-editor.org/info/rfc6809>.
	8.2. Informative References		8.2. Informative References
	[I-D.ietf-stir-rfc4474bis]		[I-D.ietf-stir-rfc4474bis]
	Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,		Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
	"Authenticated Identity Management in the Session		"Authenticated Identity Management in the Session
	Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-15		Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-15
	(work in progress), October 2016.		(work in progress), October 2016.
			[RFC3323] Peterson, J., "A Privacy Mechanism for the Session
			Initiation Protocol (SIP)", RFC 3323,
			DOI 10.17487/RFC3323, November 2002,
			<http://www.rfc-editor.org/info/rfc3323>.
	[RFC5039] Rosenberg, J. and C. Jennings, "The Session Initiation		[RFC5039] Rosenberg, J. and C. Jennings, "The Session Initiation
	Protocol (SIP) and Spam", RFC 5039, DOI 10.17487/RFC5039,		Protocol (SIP) and Spam", RFC 5039, DOI 10.17487/RFC5039,
	January 2008, <http://www.rfc-editor.org/info/rfc5039>.		January 2008, <http://www.rfc-editor.org/info/rfc5039>.
	Author's Address		Author's Address
	Henning Schulzrinne		Henning Schulzrinne
	FCC		FCC
	445 12th Street SW		445 12th Street SW
	Washington, DC 20554		Washington, DC 20554
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