rfc9878v1.txt		rfc9878.txt
	skipping to change at line 19 ¶		skipping to change at line 19 ¶
	October 2025		October 2025
	Updates to Private Header (P-Header) Extension Usage in Session		Updates to Private Header (P-Header) Extension Usage in Session
	Initiation Protocol (SIP) Requests and Responses		Initiation Protocol (SIP) Requests and Responses
	Abstract		Abstract
	The Third Generation Partnership Project (3GPP) has identified cases		The Third Generation Partnership Project (3GPP) has identified cases
	where different SIP private header extensions referred to as "P-"		where different SIP private header extensions referred to as "P-"
	header fields, and defined in RFC 7315, need to be included in SIP		header fields, and defined in RFC 7315, need to be included in SIP
	requests and responses currently not allowed according to RFC 7315.		requests and responses where they were not allowed according to RFC
	This document updates RFC 7315, in order to allow inclusion of the		7315. This document updates RFC 7315, in order to allow inclusion of
	affected "P-" header fields in such requests and responses. This		the affected "P-" header fields in such requests and responses. This
	document obsoletes RFC 7976. The changes related to RFC 7976 involve		document obsoletes RFC 7976. The changes related to RFC 7976 involve
	the inclusion of the P-Visited-Network-ID header field in SIP		the inclusion of the P-Visited-Network-ID header field in SIP
	responses.		responses.
	This document also makes updates to RFC 7315 in order to fix		This document also makes updates to RFC 7315 in order to fix
	misalignments that occurred when RFC 3455 was updated and		misalignments that occurred when RFC 3455 was obsoleted by RFC 7315.
	subsequently obsoleted by the publication of RFC 7315.
	Status of This Memo		Status of This Memo
	This document is not an Internet Standards Track specification; it is		This document is not an Internet Standards Track specification; it is
	published for informational purposes.		published for informational purposes.
	This document is a product of the Internet Engineering Task Force		This document is a product of the Internet Engineering Task Force
	(IETF). It represents the consensus of the IETF community. It has		(IETF). It represents the consensus of the IETF community. It has
	received public review and has been approved for publication by the		received public review and has been approved for publication by the
	Internet Engineering Steering Group (IESG). Not all documents		Internet Engineering Steering Group (IESG). Not all documents
	skipping to change at line 87 ¶		skipping to change at line 86 ¶
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	9.2. Informative References		9.2. Informative References
	Authors' Addresses		Authors' Addresses
	1. Introduction		1. Introduction
	The Third Generation Partnership Project (3GPP) has identified cases		The Third Generation Partnership Project (3GPP) has identified cases
	where different Session Initiation Protocol (SIP) [RFC3261] private		where different Session Initiation Protocol (SIP) [RFC3261] private
	header extensions referred to as "P-" header fields, and defined in		header extensions referred to as "P-" header fields, and defined in
	[RFC7315], need to be included in SIP requests and responses		[RFC7315], need to be included in SIP requests and responses where
	currently not allowed according to [RFC7315]. This document updates		they were not allowed according to [RFC7315]. This document updates
	[RFC7315], in order to allow inclusion of the affected "P-" header		[RFC7315], in order to allow inclusion of the affected "P-" header
	fields in such requests and responses.		fields in such requests and responses.
	This document also makes updates to [RFC7315] in order to fix		This document also makes updates to [RFC7315] in order to fix
	misalignments that occurred when [RFC3455] was updated and		misalignments that occurred when [RFC3455] was updated and
	subsequently obsoleted by the publication of [RFC7315].		subsequently obsoleted by the publication of [RFC7315].
	2. Misalignments and 3GPP Use Cases		2. Misalignments and 3GPP Use Cases
	2.1. General		2.1. General
	skipping to change at line 110 ¶		skipping to change at line 109 ¶
	[RFC7315] contains contradictory statements regarding the usage of		[RFC7315] contains contradictory statements regarding the usage of
	SIP "P-" header fields in SIP requests and responses, which leave the		SIP "P-" header fields in SIP requests and responses, which leave the
	presence of the SIP "P-" header fields in the SIP requests and		presence of the SIP "P-" header fields in the SIP requests and
	responses open to interpretation and different implementations.		responses open to interpretation and different implementations.
	Statements in Section 5.7 of [RFC7315] are not aligned with the		Statements in Section 5.7 of [RFC7315] are not aligned with the
	definitions and usage of the SIP "P-" header fields specified in		definitions and usage of the SIP "P-" header fields specified in
	Section 4 of [RFC7315]. This section describes the misalignments		Section 4 of [RFC7315]. This section describes the misalignments
	that occurred when [RFC3455] was updated and subsequently obsoleted		that occurred when [RFC3455] was updated and subsequently obsoleted
	by the publication of [RFC7315], and how they are fixed.		by the publication of [RFC7315], and how they are fixed.
	NOTE: In the case of the P-Called-Party-ID header field, allowing it		| NOTE: In the case of the P-Called-Party-ID header field,
	in PUBLISH requests was done deliberately in [RFC7315]. Therefore,		| allowing it in PUBLISH requests was done deliberately in
	it is not considered a misalignment.		| [RFC7315]. Therefore, it is not considered a misalignment.
	Since [RFC7315] was published, 3GPP defined new use cases that		Since [RFC7315] was published, 3GPP defined new use cases that
	require the RFC to be updated. This section describes the 3GPP use		require the RFC to be updated. This section describes the 3GPP use
	cases behind the updates, and the updates needed to [RFC7315] in		cases behind the updates, and the updates needed to [RFC7315] in
	order to support the use cases.		order to support the use cases.
	Section 3 updates [RFC7315], based on the misalignments and 3GPP use		Section 3 updates [RFC7315], based on the misalignments and 3GPP use
	cases.		cases.
	2.2. Misalignments		2.2. Misalignments
	skipping to change at line 190 ¶		skipping to change at line 189 ¶
	A proxy in possession of appropriate information about the access		A proxy in possession of appropriate information about the access
	technology might insert a P-Access-Network-Info header field with its		technology might insert a P-Access-Network-Info header field with its
	own values. Such values are identified by the string "network-		own values. Such values are identified by the string "network-
	provided" defined in [RFC7315]. Based on operator policy, roaming		provided" defined in [RFC7315]. Based on operator policy, roaming
	agreement, or both, the local time of the visited network may be		agreement, or both, the local time of the visited network may be
	included.		included.
	The Call Data Records (CDRs) generated within the IP Multimedia		The Call Data Records (CDRs) generated within the IP Multimedia
	Subsystem (IMS) have to contain the NPLI in order to guarantee		Subsystem (IMS) have to contain the NPLI in order to guarantee
	correct billing. When an IMS session is modified, the NPLI also		correct billing. When an IMS session is modified, the NPLI also
	needs to be stored as the location of the user at the time when the		needs to be stored, as the location of the user at the time when the
	session is modified may generate a charging event. In case of a		session is modified may generate a charging event. In case of a
	session modification event at IMS, the NPLI needs to be provided:		session modification event at IMS, the NPLI needs to be provided:
	* when the bearer establishment is triggered, or		* when the bearer establishment is triggered, or
	* at session release when the bearer deactivation is triggered, or		* at session release when the bearer deactivation is triggered, or
	* when the bearer modification is triggered, e.g., a QoS		* when the bearer modification is triggered, e.g., a QoS
	modification for the use of a newly negotiated codec.		modification for the use of a newly negotiated codec.
	In some scenarios, the bearer modification may be triggered by the		In some scenarios, the bearer modification may be triggered by the
	proxy upon reception of a Session Description Protocol (SDP) answer		proxy upon reception of a Session Description Protocol (SDP) answer
	within SIP 2xx response to the SIP INVITE request. In such case, the		within the SIP 2xx response to the SIP INVITE request. In such case,
	NPLI needs to be provided within the SIP ACK request. However,		the NPLI needs to be provided within the SIP ACK request. However,
	[RFC7315] does not allow the usage of the P-Access-Network-Info		[RFC7315] does not allow the usage of the P-Access-Network-Info
	header field in a SIP ACK request.		header field in a SIP ACK request.
	Upon reception of the SDP answer within SIP 2xx response on the SIP		Upon reception of the SDP answer within a SIP 2xx response on the SIP
	INVITE request, a proxy may initiate procedures to obtain the NPLI		INVITE request, a proxy may initiate procedures to obtain the NPLI
	and may include the P-Access-Network-Info header field with the NPLI		and may include the P-Access-Network-Info header field with the NPLI
	in the SIP ACK request.		in the SIP ACK request.
	The P-Access-Network-Info header field shall not be included in SIP		The P-Access-Network-Info header field shall not be included in SIP
	ACK requests triggered by non-2xx responses.		ACK requests triggered by non-2xx responses.
	2.3.3. P-Charging-Vector		2.3.3. P-Charging-Vector
	[RFC7315] defines an Inter Operator Identifier (IOI) to enable		[RFC7315] defines an Inter Operator Identifier (IOI) to enable
	skipping to change at line 244 ¶		skipping to change at line 243 ¶
	reason, it is necessary that the P-Charging-Vector header field,		reason, it is necessary that the P-Charging-Vector header field,
	which carries the transit IOI information, is included in each SIP		which carries the transit IOI information, is included in each SIP
	request and response. However, [RFC7315] does not allow the usage of		request and response. However, [RFC7315] does not allow the usage of
	the P-Charging-Vector header field in the SIP ACK request.		the P-Charging-Vector header field in the SIP ACK request.
	A SIP proxy that supports this extension and receives the SIP ACK		A SIP proxy that supports this extension and receives the SIP ACK
	request may include a P-Charging-Vector header field in the SIP ACK		request may include a P-Charging-Vector header field in the SIP ACK
	request.		request.
	The P-Charging-Vector header field shall not be included in SIP ACK		The P-Charging-Vector header field shall not be included in SIP ACK
	requests triggered by SIP non-2xx responses.		requests triggered by non-2xx responses.
	3. Updates to RFC 7315		3. Updates to RFC 7315
	This section contains the update to Section 5.7 of [RFC7315], in		This section contains the update to Section 5.7 of [RFC7315], in
	order to implement the misalignment fixes and the 3GPP requirements		order to implement the misalignment fixes and the 3GPP requirements
	described in Section 2.		described in Section 2. In the old text, blank lines have been added
			for readability.
	Old text:		Old text:
	| The P-Associated-URI header field can appear in SIP REGISTER		| The P-Associated-URI header field can appear in SIP REGISTER
	| method and 2xx resonses [sic]. The P-Called-Party-ID header field		| method and 2xx resonses [sic].
	| can appear in SIP INVITE, OPTIONS, PUBLISH, SUBSCRIBE, and MESSAGE		|
	| methods and all responses. The P-Visited-Network-ID header field		| The P-Called-Party-ID header field can appear in SIP INVITE,
	| can appear in all SIP methods except ACK, BYE, and CANCEL and all		| OPTIONS, PUBLISH, SUBSCRIBE, and MESSAGE methods and all
	| responses. The P-Access-Network-Info header field can appear in		| responses.
	| all SIP methods except ACK and CANCEL. The P-Charging-Vector		|
	| header field can appear in all SIP methods except CANCEL. The P-		| The P-Visited-Network-ID header field can appear in all SIP
	| Charging-Function-Addresses header field can appear in all SIP		| methods except ACK, BYE, and CANCEL and all responses.
			|
			| The P-Access-Network-Info header field can appear in all SIP
	| methods except ACK and CANCEL.		| methods except ACK and CANCEL.
			|
			| The P-Charging-Vector header field can appear in all SIP methods
			| except CANCEL.
			|
			| The P-Charging-Function-Addresses header field can appear in all
			| SIP methods except ACK and CANCEL.
	New text:		New text:
	| The P-Associated-URI header field can appear in SIP REGISTER 2xx		| The P-Associated-URI header field can appear in SIP REGISTER 2xx
	| responses.		| responses.
	|		|
	| The P-Called-Party-ID header field can appear in the SIP INVITE,		| The P-Called-Party-ID header field can appear in the SIP INVITE,
	| OPTIONS, PUBLISH, REFER, SUBSCRIBE, and MESSAGE requests.		| OPTIONS, PUBLISH, REFER, SUBSCRIBE, and MESSAGE requests.
	|		|
	| The P-Visited-Network-ID header field can appear in all SIP		| The P-Visited-Network-ID header field can appear in all SIP
	skipping to change at line 354 ¶		skipping to change at line 362 ¶
	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,
	<https://www.rfc-editor.org/info/rfc3261>.		<https://www.rfc-editor.org/info/rfc3261>.
	[RFC7315] Jesske, R., Drage, K., and C. Holmberg, "Private Header		[RFC7315] Jesske, R., Drage, K., and C. Holmberg, "Private Header
	(P-Header) Extensions to the Session Initiation Protocol		(P-Header) Extensions to the Session Initiation Protocol
	(SIP) for the 3GPP", RFC 7315, DOI 10.17487/RFC7315, July		(SIP) for the 3GPP", RFC 7315, DOI 10.17487/RFC7315, July
	2014, <https://www.rfc-editor.org/info/rfc7315>.		2014, <https://www.rfc-editor.org/info/rfc7315>.
	[TS23.228] 3GPP, "IP Multimedia Subsystem (IMS); Stage 2", Version		[TS23.228] 3GPP, "IP Multimedia Subsystem (IMS); Stage 2", 3GPP
	13.6.0, Release 13, 3GPP TS 23.228, June 2016,		TS 23.228,
	<https://www.3gpp.org/ftp//Specs/		<https://portal.3gpp.org/desktopmodules/Specifications/
	archive/23_series/23.228/23228-g30.zip>.		SpecificationDetails.aspx?specificationId=821>.
	[TS24.229] 3GPP, "IP multimedia call control protocol based on		[TS24.229] 3GPP, "IP multimedia call control protocol based on
	Session Initiation Protocol (SIP) and Session Description		Session Initiation Protocol (SIP) and Session Description
	Protocol (SDP); Stage 3", Version 13.6.0, Release 13, 3GPP		Protocol (SDP); Stage 3", 3GPP TS 24.229,
	TS 24.229, June 2016, <https://www.3gpp.org/ftp/Specs/		<https://portal.3gpp.org/desktopmodules/Specifications/
	archive/24_series/24.229/24229-d60.zip>.		SpecificationDetails.aspx?specificationId=1055>.
	9.2. Informative References		9.2. Informative References
	[RFC3455] Garcia-Martin, M., Henrikson, E., and D. Mills, "Private		[RFC3455] Garcia-Martin, M., Henrikson, E., and D. Mills, "Private
	Header (P-Header) Extensions to the Session Initiation		Header (P-Header) Extensions to the Session Initiation
	Protocol (SIP) for the 3rd-Generation Partnership Project		Protocol (SIP) for the 3rd-Generation Partnership Project
	(3GPP)", RFC 3455, DOI 10.17487/RFC3455, January 2003,		(3GPP)", RFC 3455, DOI 10.17487/RFC3455, January 2003,
	<https://www.rfc-editor.org/info/rfc3455>.		<https://www.rfc-editor.org/info/rfc3455>.
	Authors' Addresses		Authors' Addresses
End of changes. 13 change blocks.
	31 lines changed or deleted		39 lines changed or added
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