weinronk-dispatch-last-diverting-line-id-00.txt

Internet DRAFT - draft-weinronk-dispatch-last-diverting-line-id

draft-weinronk-dispatch-last-diverting-line-id

Last Version:	draft-weinronk-dispatch-last-diverting-line-id-00.txt	Tracker Entry
Date:	`19-Feb-2016`
Disposition:	expired

Dispatch Working Group N. Weinronk
Internet Draft Gamma Communications
Intended status: Informational February 18, 2016
Expires: August 2016

Last Diverting Line Identity
draft-weinronk-dispatch-last-diverting-line-id-00.txt

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Abstract

This document proposes an extension to the Session Initiation
Protocol (SIP).

In cases where applications/services (for example verification /
billing) are provided by a network that is not the originating
network the Network Asserted Identity is needed to provide these
services.

This extension provides the ability for a 'diversion service' to
provide a Network Asserted Identity of the last diverting user to
these applications/services.

This extension defines a new general header, Last Diverting Line
Identity which conveys the Network Asserted Identity of the
diverting party to these applications/services.

Table of Contents

1. Introduction ................................................ 3
2. Conventions used in this document............................ 3
3. Definitions ................................................. 3
4. Abbreviations ............................................... 3
5. Overview .................................................... 4
6. Formal Syntax ............................................... 5
7. Why not use existing headers................................. 6
8. Security Considerations...................................... 6
9. IANA Considerations ......................................... 7
9.1. Registration of SIP Last-Diverting-Line-Identity Header .. 7
9.2. Registration of "ldli" for SIP Privacy Headers...........7
10. References ................................................. 8

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10.1. Normative References................................... 8
11. Acknowledgments ............................................ 8

1. Introduction

This extension provides the ability for a 'diversion service' to
provide a Network Asserted Identity of the last diverting user to
these applications/services.

This extension defines a new general header, Last Diverting Line
Identity which conveys the Network Asserted Identity of the
diverting party to these applications/services.

In the legacy telephony network in the UK this information is
provided by the Last Diverting Line Identity parameter. Note: This
ISUP parameter is defined in the UK under the 'Nationally defined
for National User' parameter code range of values.

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].

In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.

3. Definitions

Diversion:

The 'diversion service' could be defined as in [RFC7044] or as in
[TS.24604].

NICC:

The UK Interoperability Standards Organisation.

4. Abbreviations

3GPP - 3rd Generation Partnership Project

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ETSI - European Telecommunication Standard Institute

ISDN - Integrated Services Digital Network

ISUP - ISDN User Part

ITU - International Telecommunication Union

SIP - Session Initiation Protocol

TS - Technical Specification

UA - User Agent

UK - United Kingdom

5. Overview

This extension provides the ability for a 'diversion service' to
provide a Network Asserted Identity of the last diverting user to
these applications/services.

This extension defines a new general header, Last Diverting Line
Identity which conveys the Network Asserted Identity of the
diverting party to these applications/services.

It could be added by SIP UAs, SIP Redirect Servers or SIP Proxy
Servers.

Example headers are:

Last-Diverting-Line-Identity: <sip:+441632123456@example.com;user=phone>

Last-Diverting-Line-Identity: <tel:+441632123456>

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6. Formal Syntax

The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [RFC2234].

Definition of new Last Diverting Line Identity header field:

The Last Diverting Line Identity header field is used among trusted
SIP entities (typically intermediaries) to carry the verified
identity of the diverting user.

Last-Diverting-Line-Identity = "Last-Diverting-Line-Identity" HCOLON
LDLI-value

LDLI-value = name-addr

A Last-Diverting-Line-Identity header field value MUST consist of
exactly one name-addr. It MUST be a sip, sips or tel URI.

6.1 The "ldli" Privacy Type

This specification adds a new priv-value to the Privacy header
[RFC3323]. The presence of this privacy type in a Privacy header
field indicates that the user would like the Last Diverting Line
Identity to be kept private with respect to untrusted SIP entities.

priv-value = "ldli"

If the "ldli" priv-value is not present the LDLI-value presentation
is allowed.

If the "ldli" priv-value is present then the LDLI-value presentation
is restricted.

This document adds the following entry to Table 2 of [RFC3261]:

Header field where proxy ACK BYE CAN INV OPT REG
----------- ----- ----- --- --- --- --- --- ---
Last-Diverting-Line-Identity amdr - - - o - -

Header field where proxy SUB NOT REF INF UPD PRA
----------- ----- ----- --- --- --- --- --- ---
Last-Diverting-Line-Identity amdr - - - - - -

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The Last-Diverting-Line-identity header carries the following
information, with the mandatory parameters required when the header
is included in a request:

LDLI-value a mandatory parameter for capturing the Last Diverting
Line Identity.

7. Why not use existing headers

Use of the last History-Info header entry [RFC7044] was considered
however this is mapped to/from the ISUP Redirecting Number and there
are cases where the ISUP Redirecting Number is not the Network
Asserted Identity of the last diverting user - for example the ETSI
ISDN Partial Re-routing service as implemented in the UK.

Note: In the UK the mapping would be to/from the new SIP header and
the UK ISUP Last Diverting Line Identity parameter which provides
the same functionality in UK ISUP leaving the ISUP Redirecting
Number mapping to/from History-Info header as in the existing IETF /
3GPP / ITU / NICC specifications.

8. Security Considerations

This document defines a header field for SIP. The use of the
Transport Layer Security (TLS) protocol [RFC5246] as a mechanism to
ensure the overall confidentiality of the Last-Diverting-Line-
Identity header fields is strongly RECOMMENDED. If TLS is NOT used,
the intermediary MUST ensure that the messages are only sent within
an environment that is secured by other means or that the messages
don't leave the intermediary's domain. This results in Last-
Diverting-Line-Identity's having at least the same level of security
as other headers in SIP that are inserted by intermediaries. With
TLS, Last-Diverting-Line-Identity header fields are no less, nor no
more, secure than other SIP header fields, which generally have even
more impact on the subsequent processing of SIP sessions than the
Last-Diverting-Line-Identity header field.

Note that while using the SIPS scheme (as per [RFC5630]) protects
Last-Diverting-Line-Identity from tampering by arbitrary parties
outside the SIP message path, all the intermediaries on the path are
trusted implicitly. A malicious intermediary could arbitrarily
delete, rewrite, or modify Last-Diverting-Line-Identity. This
specification does not attempt to prevent or detect attacks by
malicious intermediaries.

In terms of ensuring the privacy of LDLI-value, the same security
considerations as those described in [RFC3323] apply. The Privacy

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Service that's defined in [RFC3323] MUST also support the new
Privacy header field priv-value of "ldli".

9. IANA Considerations

9.1. Registration of SIP Last-Diverting-Line-Identity Header

This document defines a new SIP header field name:

Last-Diverting-Line-Identity

The following changes should be made to the header sub-registry
under:

http:///www.iana.org/assignments/sip-parameters

The following row has been added to the header field section:

Header Name Compact Form Reference
----------- ------------ ---------

Last-Diverting-Line-Identity none [????]

9.2. Registration of "ldli" for SIP Privacy Headers

This document defines a new priv-value for the SIP Privacy header:

ldli

The following changes should be made to

http://www.iana.org/assignments/sip-priv-values

The following has been added to the registration for the SIP Privacy
header:

Name Description Registrant Reference
---- ----------- ---------- ---------

ldli Privacy requested for [????] [????]

Last-Diverting-Line-Identity

header

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10. References

10.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.

[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.

[RFC3323] Peterson, J., "A Privacy Mechanism for the Session
Initiation Protocol (SIP)", RFC 3323, November 2002.

[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.

[RFC5630] Audet, F., "The Use of the SIPS URI Scheme in the Session
Initiation Protocol (SIP)", RFC 5630, October 2009.

[RFC7044] Barnes, M., Audet, F., Schubert, S., van Elburg, J., and
C. Holmberg, "An Extension to the Session Initiation
Protocol (SIP) for Request History Information", RFC
7044,February 2014.

[TS.24604] 3GPP, "Communication Diversion (CDIV) using IP Multimedia
(IM) Core Network (CN) subsystem; Protocol specification"

11. Acknowledgments

NICC SIP Task Group

This document was prepared using 2-Word-v2.0.template.dot.

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Authors' Address

Nigel Weinronk
Gamma Communications

Phone: +443332403421
Email: nigel.weinronk@gamma.co.uk

Contributors' Addresses

Nick Ireland
NICC

Phone: +447889861066

Email: nick.ireland@niccstandards.org.uk

Perry Wilks
BT

Phone: +442087262646
Email: perry.wilks@bt.com

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