SIP Call-Info Parameters for Rich Call Data
draft-ietf-sipcore-callinfo-rcd-12
| Document | Type | Active Internet-Draft (sipcore WG) | |
|---|---|---|---|
| Authors | Chris Wendt , Jon Peterson | ||
| Last updated | 2024-07-23 (Latest revision 2024-07-22) | ||
| Replaces | draft-wendt-sipcore-callinfo-rcd | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Document shepherd | Jean Mahoney | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | mahoney@nostrum.com |
draft-ietf-sipcore-callinfo-rcd-12
Network Working Group C. Wendt
Internet-Draft Somos
Intended status: Standards Track J. Peterson
Expires: 22 January 2025 Neustar
21 July 2024
SIP Call-Info Parameters for Rich Call Data
draft-ietf-sipcore-callinfo-rcd-12
Abstract
This document describes a usage of the SIP Call-Info header field
that incorporates Rich Call Data (RCD) associated with the identity
of the calling party in order to provide to the called party a
description of the caller or details about the reason for the call.
RCD includes information about the caller beyond the telephone number
such as a calling name, or a logo, photo, or jCard object
representing the caller, which can help the called party decide
whether to answer the phone. The elements defined for this purpose
are intended to be extensible in order to accommodate related
information about calls and to be compatible and complimentary with
the STIR/PASSporT RCD framework.
This document defines three new parameters 'call-reason', 'verified',
and 'integrity' for the SIP Call-Info header field and also a new
token ("jcard") for the 'purpose' parameter of the Call-Info header
field. It also provides guidance on the use of the Call-Info
'purpose' parameter token, "icon".
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 22 January 2025.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. A Call-Info Framework for Carrying Rich Call Data . . . . . . 6
5. "jcard" Call-Info 'purpose' Token . . . . . . . . . . . . . . 7
6. 'call-reason' Call-Info Parameter . . . . . . . . . . . . . . 10
7. 'verified' Call-Info Parameter . . . . . . . . . . . . . . . 11
8. 'integrity' Call-Info Parameter . . . . . . . . . . . . . . . 13
9. Usage and an Example of Call-Info for RCD . . . . . . . . . . 15
10. Usage of jCard and Property-Specific Usage . . . . . . . . . 16
10.1. Usage of URIs in jCard . . . . . . . . . . . . . . . . . 17
10.2. Usage of Multimedia Data in jCard or with Icon . . . . . 17
10.3. Cardinality . . . . . . . . . . . . . . . . . . . . . . 18
10.4. Identification Properties . . . . . . . . . . . . . . . 19
10.4.1. "fn" Property . . . . . . . . . . . . . . . . . . . 19
10.4.2. "n" Property . . . . . . . . . . . . . . . . . . . . 19
10.4.3. "nickname" Property . . . . . . . . . . . . . . . . 20
10.4.4. "photo" Property . . . . . . . . . . . . . . . . . . 20
10.5. Delivery Addressing Properties . . . . . . . . . . . . . 20
10.5.1. "adr" Property . . . . . . . . . . . . . . . . . . . 20
10.6. Communications Properties . . . . . . . . . . . . . . . 21
10.6.1. "tel" Property . . . . . . . . . . . . . . . . . . . 21
10.6.2. "email" Property . . . . . . . . . . . . . . . . . . 21
10.6.3. "lang" Property . . . . . . . . . . . . . . . . . . 22
10.7. Geographical Properties . . . . . . . . . . . . . . . . 22
10.7.1. "tz" Property . . . . . . . . . . . . . . . . . . . 22
10.7.2. "geo" Property . . . . . . . . . . . . . . . . . . . 22
10.8. Organizational Properties . . . . . . . . . . . . . . . 23
10.8.1. "title" Property . . . . . . . . . . . . . . . . . . 23
10.8.2. "role" Property . . . . . . . . . . . . . . . . . . 23
10.8.3. "logo" Property . . . . . . . . . . . . . . . . . . 23
10.8.4. "org" Property . . . . . . . . . . . . . . . . . . . 24
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10.9. Explanatory Properties . . . . . . . . . . . . . . . . . 24
10.9.1. "categories" Property . . . . . . . . . . . . . . . 24
10.9.2. "note" Property . . . . . . . . . . . . . . . . . . 24
10.9.3. "sound" Property . . . . . . . . . . . . . . . . . . 25
10.9.4. "uid" Property . . . . . . . . . . . . . . . . . . . 25
10.9.5. "url" Property . . . . . . . . . . . . . . . . . . . 25
10.9.6. "version" Property . . . . . . . . . . . . . . . . . 26
11. Extension of jCard . . . . . . . . . . . . . . . . . . . . . 26
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
12.1. SIP Call-Info Header Field 'purpose' Parameter Token . . 26
12.2. SIP Call-Info Header Field 'call-reason' Parameter . . . 27
12.3. SIP Call-Info Header Field 'verified' Parameter . . . . 27
12.4. SIP Call-Info Header Field 'integrity' Parameter . . . . 27
13. Security Considerations . . . . . . . . . . . . . . . . . . . 28
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
14.1. Normative References . . . . . . . . . . . . . . . . . . 28
14.2. Informative References . . . . . . . . . . . . . . . . . 30
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction
Signaling protocols in telephone networks have long supported the
delivery of a 'calling name' from the originating side to the
terminating side, though in practice, the terminating side is often
left to derive a name from the calling-party number by consulting a
local address book or an external database. SIP [RFC3261] similarly
can carry a 'display-name' in the From header field value from the
originating to terminating side, though it is an unsecured field that
is not commonly trusted and is often replaced or ignored. The same
can be considered true of information in the Call-Info header field
in SIP.
To allow calling parties to initiate, and called parties to receive,
a more comprehensive, deterministic, and extensible Rich Call Data
(RCD) for incoming calls, this document defines a new parameter
('call-reason') for the SIP Call-Info header field [RFC3261] and also
a new token ("jcard") for the 'purpose' parameter of the Call-Info
header field. For this document and depending on the policies of the
communications system, a calling party could be either the end user
device (e.g., a SIP user agent (UA)) or a network service as part of
a telephone service provider. Similarly, a called party could be an
end user device or the network telephone service provider acting on
behalf of the recipient of the call.
In order to properly translate and communicate some of the
authenticated and trusted properties of 'rcd' claims defined in
[I-D.ietf-stir-passport-rcd], this document defines two new
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parameters, 'verified' and 'integrity'. These parameters help
translate RCD information that had been sent via a SIP network to,
for example, a SIP entity on the edge of the network-to-network
interface (NNI) that contains a verification service as defined in
[RFC8224] and further defined specific to RCD information in
[I-D.ietf-stir-passport-rcd]. The verification procedures include
the concepts of successful verification of the "rcd" claims and can
be correspondingly translated and represented in the Call-Info header
field via these new parameters.
Used on its own, this specification assumes that the called party UA
can trust the SIP network or the SIP provider to assign, deliver, and
protect the correct RCD information as an end-to-end security policy.
However, as is true in many interconnected communications services,
this end-to-end trust cannot be guaranteed. Therefore, the
recommended approach is that the entity inserting the Call-Info
header field should also sign the caller information via STIR-defined
protocol tools [RFC7340] for SIP [RFC8224] and specifically through
the use of RCD or the "rcd" PASSporT defined in
[I-D.ietf-stir-passport-rcd].
Alternatively, this specification can be utilized in conjunction with
the protocols defined in [I-D.ietf-stir-passport-rcd] as part of the
communications signaling path, specifically in the trusted UNI device
interface at the terminating side as part of an authenticated,
network-to-device, trusted signaling where a device may not have the
ability to verify the "rcd" PASSporT, but it can receive the RCD
information from the Call-Info header field as defined in this
specification.
[RFC7852] provides a means of carrying additional data about callers
for the purposes of emergency services (especially Section 4.4
(Owner/Subscriber Information) of [RFC7852]). This specification
provides an overlapping functionality for non-emergency cases.
Rather than overloading its "EmergencyCallData" Call-Info 'purpose'
parameter value, this document defines a separate 'purpose' parameter
for the more generic delivery of information via jCard [RFC7095].
This document borrows from [RFC7852] the capability to carry a data
structure as a body, through the use of the "cid" URI scheme
[RFC2392].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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3. Overview
In this document, we provide a framework for the use of Call-Info
header field to carry RCD in SIP [RFC3261]. The Call-Info header
field (defined in [RFC3261], Section 20.9) defines a 'purpose'
parameter. In addition to providing guidance on calling name
practices and the use of the existing 'purpose' parameter token,
"icon", this document expands on other types of RCD by defining a new
'purpose' token, "jcard", and three new parameters, 'call-reason',
'verified', and 'integrity' for the Call-Info header field to align
with RCD as defined in the STIR framework [RFC8224] and with "rcd"
PASSporTs defined in [I-D.ietf-stir-passport-rcd].
The 'purpose' parameter token "jcard" is used to associate RCD
related to the identity of the calling party in the form of a jCard
[RFC7095]. While there is a "card" token defined in [RFC3261] which
could be considered to have an overlapping purpose, the "jcard" token
is intended to denote the jCard profile defined in this document for
use in the Call-Info header field for RCD. The choice of jCard in
this specification is guided by two things. First, JSON has become
the default and is generally the widely accepted, optimally supported
format for transmission, parsing, and manipulation of data on IP
networks, and jCard represents an extensible method of providing
information about a person or business associated with a call.
Second, jCard has been defined in [I-D.ietf-stir-passport-rcd] and
has been adopted by PASSporT [RFC8225] because of the usage of JSON
Web Tokens (JWT) [RFC7519].
The new Call-Info header field parameter 'call-reason' provides a
string or other object that conveys the caller's intent or reason for
calling to help the called party understand the context and intent of
the call and why they may want to answer the call.
The new Call-Info header field parameter 'verified' provides an
indication, with the value "true", to represent the results of the
verification procedures that were performed by the sender of the
Call-Info header field. The new Call-Info header field parameter
'integrity' provides a mechanism to associate an integrity hash
string, as defined in [I-D.ietf-stir-passport-rcd] in Section 8.2,
that is associated with the content of the resource referenced by the
URI represented in the Call-Info header field.
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4. A Call-Info Framework for Carrying Rich Call Data
This specification extends the Call-Info header field to be
compatible and complimentary to the RCD framework defined in
[I-D.ietf-stir-passport-rcd]. Typically, a SIP-based call involves
multiple hops through different trusted and untrusted networks. The
STIR framework [RFC7340] addresses the protection of the carriage of
call information and identities over untrusted networks, which wasn't
addressed in the core SIP specifications. [RFC3261], Section 20.9
defines the Call-Info header field as the mechanism for carrying
call- and caller-related information and also provides procedures for
defining new 'purpose' parameter tokens. This document discusses the
use of existing tokens and defines a new 'purpose' token to
correspond to the RCD framework.
There are a number of RCD information types that can be transmitted
in the Call-Info header field of a SIP request. The STIR RCD
specification [I-D.ietf-stir-passport-rcd] defines calling name, a
logo or icon associated with the caller, and a call reason string.
It also discusses an extensible way of carrying caller information
using jCard [RFC7095]. It may be that future specifications extend
information types and, similar to how this document extends the Call-
Info header field to provide corresponding functionality to STIR RCD,
it is RECOMMENDED that future specifications also provide
corresponding Call-Info extensions.
The RCD framework defined both in this document as well as in
[I-D.ietf-stir-passport-rcd] carries call-specific information. The
insertion of RCD is intended to be singular in that the receiving
party should not be required to make any call-specific decisions
based on redundant, duplicate, or conflicting RCD. The RCD
information is either intended to be added by a party that is
authoritative over that information or to have been translated from a
verified STIR RCD PASSporT and unmodified once in a trusted domain.
Any additional parties involved in the call path SHOULD NOT modify
the Call-Info header field or add additional Call-Info header fields
related to RCD. The insertion of the RCD Call-Info header field
should be considered a trusted action based on trusted information,
and the information SHOULD NOT be considered modifiable as a best
practice.
As discussed in [I-D.ietf-stir-passport-rcd], the calling name uses
the display-name value of the From header field [RFC3261] of the
request. Alternatively, for some calls, the calling name may come
from the P-Asserted-ID header field [RFC3325]. While this is out of
scope for Call-Info header field in terms of the representation of
the display-name value, this document does discuss the representation
of the verification of this value using the 'verified' parameter.
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For logos or icons that can represent the calling party, the
'purpose' token "icon" [RFC3261] is used to indicate a URI for an
image resource that can be displayed to the user receiving the SIP
request. For the purpose of this document and the transmission of
RCD, the "icon" 'purpose' token should be used as defined.
Section 8.2 provides high-level guidance on image formatting and
related information.
This document defines 'call-reason' as a new parameter for the Call-
Info header field. This parameter carries a string indicating the
reason for the call.
jCard is a comprehensive and extensible mechanism defined in the STIR
RCD framework. While [RFC3261] specifies a "card" 'purpose' token,
the intent of defining a new "jcard" 'purpose' token is to use the
JSON jCard format [RFC7095] and to provide guidance for the use and
non-use of jCard attributes to describe the calling party in a
communications session as well to provide some security
considerations around that information. These topics are covered in
the next sections.
5. "jcard" Call-Info 'purpose' Token
The Call-Info 'purpose' token "jcard" indicates support of RCD
associated with the identity of a calling party in a SIP call
[RFC3261], Section 20.9. The format of a Call-Info header field when
using the "jcard" token is as follows.
The Call-Info header field is defined to include a URI that points to
a resource that is a jCard JSON object [RFC7095]. The media type for
the JSON text MUST be set as application/json with a default encoding
of UTF-8 [RFC8259]. This MAY be carried directly in the Call-Info
header field URI using the "data" URI scheme. A jCard also MAY be
carried in the body of the SIP request bearing this Call-Info header
field via the "cid" URI scheme [RFC2392]. Alternatively, the URI
MUST define the use HTTPS or a transport that can validate the
integrity of the source of the resource as well as the transport
channel through which the resource is retrieved. If, in the specific
deployment environment of SIP, the source or integrity of the RCD
information cannot be trusted, then the use of the STIR RCD framework
defined in [I-D.ietf-stir-passport-rcd] should be considered.
The jCard is intended to contain multiple information elements about
the calling party. A call and its corresponding single RCD-related
Call-Info header field MUST only contain a single "jcard" token.
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The fields like "fn", "photo", or "logo" if used with the use of
"icon" calling name in From or P-Asserted-ID header field or purpose
token, as described in the previous section, MUST either match or be
avoided to allow the called party to clearly determine the intended
calling name or icon.
An example of a Call-Info header field is:
Call-Info: <https://example.com/qbranch.json>;purpose=jcard
An example of the contents of a URL-linked jCard JSON file is shown
as follows:
["vcard",
[
["version",{},"text","4.0"],
["fn",{},"text","Q Branch"],
["org",{},"text","MI6;Q Branch Spy Gadgets"],
["photo",{},"uri","https://example.com/photos/q-256x256.png"],
["logo",{},"uri","https://example.com/logos/mi6-256x256.jpg"],
["logo",{},"uri","https://example.com/logos/mi6-64x64.jpg"]
]
]
An example SIP INVITE using the "data" URI scheme is as follows:
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INVITE sip:alice@example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
To: Alice <sip:alice@example.com>
From: Bob <sip:12155551000@example.com;user=phone>;tag=1928301774>
Call-ID: a84b4c76e66710
Call-Info: <data:application/json,["vcard",[["version",{},"text",
"4.0"],["fn",{},"text","Q Branch"],["org",{},"text","MI6;Q Branch
Spy Gadgets"],["photo",{},"uri","https://example.com/photos/quart
ermaster-256x256.png"],["logo",{},"uri","https://example.com/log
os/mi6-256x256.jpg"],["logo",{},"uri","https://example.com/logos/
mi6-64x64.jpg"]]]\>;purpose=jcard;call-reason="Rendezvous for
Little Nellie"
CSeq: 314159 INVITE
Max-Forwards: 70
Date: Fri, 25 Sep 2015 19:12:25 GMT
Contact: <sip:12155551000@gateway.example.com>
Content-Type: application/sdp
v=0
o=UserA 2890844526 2890844526 IN IP4 pc33.atlanta.example.com
s=Session SDP
c=IN IP4 pc33.atlanta.example.com
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
An example SIP INVITE using the "cid" URI scheme is as follows:
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INVITE sip:alice@example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
To: Alice <sip:alice@example.com>
From: Bob <sip:12155551000@example.com;user=phone>;tag=1928301774>
Call-ID: a84b4c76e66710
Call-Info: <cid:12155551000@example.com>;purpose=jcard;
call-reason="Rendezvous for Little Nellie"
CSeq: 314159 INVITE
Max-Forwards: 70
Date: Fri, 25 Sep 2015 19:12:25 GMT
Contact: <sip:12155551000@gateway.example.com>
Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ...
--boundary1
Content-Type: application/sdp
v=0
o=UserA 2890844526 2890844526 IN IP4 pc33.atlanta.example.com
s=Session SDP
c=IN IP4 pc33.atlanta.example.com
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
--boundary1
Content-Type: application/json
Content-ID: <12155551000@example.com>
["vcard",[["version",{},"text","4.0"],["fn",{},"text","Q Branch"],
["org",{},"text","MI6;Q Branch Spy Gadgets"],["photo",{},"uri","ht
tps://example.com/photos/quartermaster-256x256.png"],["logo",{},"u
ri","https://example.com/logos/mi6-256x256.jpg"],["logo",{},"uri",
"https://example.com/logos/mi6-64x64.jpg"]]]
6. 'call-reason' Call-Info Parameter
This specification defines a new parameter that extends the overall
content of the RCD-related Call-Info header field. As other
parameters may be defined in the future, this parameter is intended
to be separate and distinct from the other URI and 'purpose' tokens
that may proceed these parameters.
This new parameter of the Call-Info header field is called 'call-
reason'. The 'call-reason' parameter is intended to convey a short
textual message suitable for display to an end user during call
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alerting. As a general guideline, this message SHOULD be no longer
than 64 characters; displays that support this specification may be
forced to truncate messages that cannot fit onto a screen. This
message conveys the caller's intention in contacting the callee. It
is an optional parameter, and the sender of a SIP request cannot
guarantee that its display will be supported by the terminating
endpoint. The manner in which this reason is set by the caller is
outside the scope of this specification.
An alternative approach would have been to use the value of Subject
header field [RFC3261] to convey the reason for the call. However,
because the Subject header field has seen little historical use in
SIP implementations and its specification describes its potential use
in filtering, it seemed prudent to define a new means of carrying a
call reason indication.
An example of a Call-Info header field value with the "call-reason"
parameter follows:
Call-Info: <https://example.com/jbond.json>;purpose=jcard;
call-reason="For your ears only"
In the case that there is only a 'call-reason' or 'verified'
parameter or any future parameters that may be defined and no need
for a purpose parameter with no associated URI, it is RECOMMENDED to
include a null data URI, "data:" as the URI. That purpose parameter
MUST be "jcard" defined in this document to avoid any conflicts with
existing implementations and previously defined purpose parameters.
As an example:
Call-Info: <data:>;purpose=jcard;
call-reason="For your ears only"
7. 'verified' Call-Info Parameter
This specification defines an additional new parameter, the
'verified' parameter, that extends and complements the content
conveyed by the RCD-related Call-Info header field. This parameter
is intended to be used to indicate to the recipient that the
information contained in the Call-Info header field has been verified
by verification procedures for claims defined in
[I-D.ietf-stir-passport-rcd] Section 8. It should be considered
separate and distinct and appear once for a given Call-Info header
instance from the other URI and 'purpose' tokens that may proceed or
come after this parameters.
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There is a single valid value associated with the 'verified'
parameter of 'true'. The value 'true' indicates to the recipient
that the party that included the Call-Info header field performed a
successful verification of the information represented. As a general
principle of Call-Info header field information, the recipients
ability to trust the 'verified' parameter is based on the trusted
relationship of whom they are receiving the SIP request.
Example where the parameter verified="true" is used to represent that
a verification procedure has been performed within a trust domain to
indicate the 'icon' URL has been successfully verified:
Call-Info: <https://example.com/jbond.png>;purpose=icon;verified="true"
In addition to the use of the indication of successful verification
of RCD information, an important usage of the 'verified' parameter is
for the indication of verified "display-name" information, sometimes
referred to as calling name or CNAM.
In the following example, a call was delivered via an NNI network
relationship to a terminating provider with the following STIR RCD
PASSporT.
Protected Header
{
"alg":"ES256",
"typ":"passport",
"ppt":"rcd",
"x5u":"https://cert.example.org/passport.pem"
}
Payload
{
"dest":{"tn":["12025551001"]},
"iat":1443208345,
"orig":{"tn":"12025551000"},
"rcd":{"nam":"James Bond","icn":"https://example.com/jbond.png"}
}
The terminating provider receives a SIP INVITE with an identity
header containing the STIR RCD PASSporT is verified through a
verification service. The provider then wants to deliver the call to
an end device in the trusted and authenticated UNI network. The
provider uses local policies to determine the information desired to
present to the end device. The following example SIP INVITE could be
used to represent the RCD information using two Call-Info header
fields. Because the verification of both the icon and calling name
passed, a Call-Info header for the 'icon' is added with a
verified="true" parameter, and the use of Call-Info with a null data
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URI is used, as discussed in the "call-reason" section above. This
document defines the convention that when a Call-Info header field
with a null data URI, "data:", a default purpose of "jcard" and
adding a verified="true" indicates that the display-name information
in either the From and/or P-Asserted-ID header field has been
verified via RCD verification procedures.
Example SIP INVITE described above:
INVITE sip:qbranch@example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
To: "QBranch" <sip:qbranch@example.com>
From: "James Bond" <sip:12155551000@example.com;user=phone>;tag=1928>
Call-ID: a84b4c76e66710
Call-Info: <https://example.com/jbond.png>;purpose=icon;verified="true"
Call-Info: <data:>;purpose=jcard;verified="true"
CSeq: 314159 INVITE
Max-Forwards: 70
Date: Fri, 25 Sep 2025 19:12:25 GMT
Contact: <sip:12155551000@gateway.example.com>
Content-Type: application/sdp
v=0
o=UserA 2890844526 2890844526 IN IP4 pc33.atlanta.example.com
s=Session SDP
c=IN IP4 pc33.atlanta.example.com
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
8. 'integrity' Call-Info Parameter
This specification defines an additional new parameter, the
'integrity' parameter, that extends and complements the integrity
information conveyed specifically by the 'rcdi' claim in the RCD-
related Call-Info header field. This parameter is intended to be
used to indicate, for a URI represented in the Call-Info header
field, the resource referenced by that URI has an associated
integrity hash value. Section 6.1 of [I-D.ietf-stir-passport-rcd]
describes the creation of the digest value including the hash
algorithm indicator a '-' separator and the hash value as a string.
The JSON pointer object container described as the container of the
'rcdi' hashes is not necessary since each hash value should only
correspond to a single URI.
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Typically, this hash value, assuming the URI and the resource pointed
to the URI don't change between the STIR RCD PASSporT and the Call-
Info URI value, the integrity value can be directly used as the same
corresponding string in both the 'rcdi' claim and the 'integrity'
parameter string value.
Example STIR RCD PASSporT:
Protected Header
{
"alg":"ES256",
"typ":"passport",
"ppt":"rcd",
"x5u":"https://cert.example.org/passport.pem"
}
Payload
{
"crn": "Rendezvous for Little Nellie",
"dest": {"tn": ["12155551001"]},
"iat": 1443208345,
"orig": {"tn": "12025551000"},
"rcd": {
"nam": "Q Branch Spy Gadgets",
"icn": "https://example.com/photos/q-256x256.png"
},
"rcdi": {
"/icn": "sha256-RojgWwU6xUtI4q82+kHPyHm1JKbm7+663bMvzymhkl4"
}
}
Example corresponding SIP INVITE with Call-Info information derived
from RCD information above:
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INVITE sip:qbranch@example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
To: "James Bond" <sip:12155551001@example.com;user=phone>
From: "Q Branch Spy Gadgets" <sip:12025551000@example.com;
user=phone>;tag=1928>
Call-ID: a84b4c76e66710
Call-Info: <https://example.com/photos/q-256x256.png>;purpose=icon;
verified="true";integrity="sha256-RojgWwU6xUtI4q82+kHPyHm1JKbm7+
663bMvzymhkl4"
Call-Info: <data:>;purpose=jcard;call-reason="Rendezvous for Little
Nellie";verified="true"
Call-Info: <data:>;purpose=jcard;verified="true"
CSeq: 314159 INVITE
Max-Forwards: 70
Date: Fri, 25 Sep 2025 19:12:25 GMT
Contact: <sip:12155551000@gateway.example.com>
Content-Type: application/sdp
v=0
o=UserA 2890844526 2890844526 IN IP4 pc33.atlanta.example.com
s=Session SDP
c=IN IP4 pc33.atlanta.example.com
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
9. Usage and an Example of Call-Info for RCD
The procedures for the usage of URIs and 'purpose' parameter tokens
should generally follow the procedures defined in [RFC3261]. The
following example provides both the STIR RCD PASSporT and the
corresponding set of Call-Info header fields shows the use of
multiple 'purpose' parameters to indicate a jCard and an icon and
also a 'call-reason' parameter:
Example STIR RCD PASSporT:
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Protected Header
{
"alg":"ES256",
"typ":"passport",
"ppt":"rcd",
"x5u":"https://cert.example.org/passport.pem"
}
Payload
{
"crn":"For your ears only",
"dest":{"tn":["12025551001"]},
"iat":1443208345,
"orig":{"tn":"12025551000"},
"rcd":{
"jcl":"https://example.com/qbranch.json",
"icn":"https://example.com/jbond.png"
},
"rcdi": {
"/jcl": "sha256-yHm1JKbm7+663bMvzymhkl4RojgWwU6xUtI4q82+kHP"
"/icn": "sha256-RojgWwU6xUtI4q82+kHPyHm1JKbm7+663bMvzymhkl4"
}
}
Example Call-Info header fields:
Call-Info: <data:>;purpose=jcard;verified="true"
Call-Info: <https://example.com/jbond.json>;purpose=jcard;verified=true;
integrity="sha256-yHm1JKbm7+663bMvzymhkl4RojgWwU6xUtI4q82+kHP"
Call-Info: <https://example.com/jbond.png>;purpose=icon;call-reason="For your ears only";verified=true;
integrity="sha256-RojgWwU6xUtI4q82+kHPyHm1JKbm7+663bMvzymhkl4"
10. Usage of jCard and Property-Specific Usage
Beyond the definition of the specific properties or JSON arrays
associated with each property, this specification defines a few rules
above and beyond [RFC7095] that are specific to the use of jCard for
Call-Info and RCD to ensure there is a minimum level of supported
properties to which every implementation of this specification should
adhere. This includes support for interpreting the value of these
properties and the ability to render in some appropriate form the
display capabilities of common telephone devices as well as
applications, and also includes requirements specific to textual and
graphics-capable displays.
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10.1. Usage of URIs in jCard
When one or more URIs are used in a jCard, it is important to note
that any URI-referenced data, with the exception of the top-level
usage of "jcl" as a URI to the jCard itself (unless updated by any
future extensions of this specification) MUST NOT contain any URI
references. In other words, the jCard can have URI references as
defined in the jCard specification and this document, but the content
referenced by those URIs MUST NOT have any URIs, and therefore MUST
be enforced by the client to not follow those URI references or not
render that content to the user if any URI are present in that
specific URI linked content. The purpose of this is to control the
security and more specifically to align with the content-integrity
mechanism defined in [I-D.ietf-stir-passport-rcd]. The authors do
not believe there is a scenario for which deeper URI references would
be required or even supported by the typical use of current jCard
properties. However, because jCard is extensible, this rule is set
to restrict further extension without the proper consideration of
security and integrity properties of both Call-Info usage as well as
the RCD and STIR signing of the data [I-D.ietf-stir-passport-rcd]
[RFC8224].
10.2. Usage of Multimedia Data in jCard or with Icon
For the use of the 'purpose' token "icon" or for the cases where the
jCard either incorporates URIs or includes digital images and sounds
directly via Base64 encoding, we provide recommendations to
facilitate the successful decoding and rendering of these images and
media formats.
For images, such as for the "photo" and "logo" properties, the
default image formats SHOULD be PNG [ISOPNG] or JPEG [ITUJPEG], as
these files are commonly used to support 24-bit RGB images.
Supporting older telephone devices that only support bitmap (BMP)
images [RFC7903] with a lower bit range (e.g., 16 bit, 8 bit, or 1
bit), or grayscale, or 1-bit black and white color displays, should
be considered optional or even not recommended because, at the time
of writing, they are becoming increasingly rare (i.e., typically,
devices either have color or color-aware graphical displays that
support PNG or JPEG formats or they are exclusively textual
displays).
In addition, vector images are increasingly popular to use for icons
because they support scalable images without having to send multiple
resolutions. The SVG format has gained wide support as of this
writing as a common format for vector images. At a minimum, the SVG
Tiny 1.2 specification [W3C-SVGTiny1.2] SHOULD be supported as an
additional default format for devices.
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For the cases where image files are referenced by URIs as file
resources, this document defines a character string that SHOULD be
concatenated onto the end of a file name, but before the file
extension, that signals the height and width of the image to the end
device for the convenience of determining the appropriate resolution
to retrieve without the need to retrieve all the image files. It is
also recommended that images have a square aspect ratio with equal
height and width and with a power of two value for the number of
pixels (e.g., 32x32, 128x128, 512x512). The format of the string
should be "filename-HxW", where "filename" is a unique string
representing the file, "H" represents the height in pixels, and "W"
represents the width in pixels.
It is appropriate and useful to include multiple versions of images
or sounds so that endpoints that cannot support all formats or
resolutions can select the format they do support. The convention
that is RECOMMENDED is that files that refer to the same content
should use the same filename portion. If the image format has a
specific resolution, the HxW portion of the filename should
correspond to the pixel resolution. The file extension should
reference the file type (e.g., filename.png, filename.svg, or
filename.jpg) or (e.g., filename-32x32.png, filename-64x64.png,
filename.svg, filename-32x32.jpg, or filename-64x64.jpg).
Because this is a complex and often debated topic that has evolved
over the many years of advances in image coding and display
technologies, we suggest relying on either future specifications or
industry forum specifications that might correspond to supporting
particular classes of devices to further define how URIs can
reference appropriate image formats and files.
For audio files, the recommendation is to provide mp3, m4a or mp4, or
wav files [RFC2361], although the usage of sound (for example, a
special ring tone for a particular caller) is not well defined in
this specification. Future documents should consider both usage and
potential security risks of playing sounds that are not specifically
authorized by a device user.
10.3. Cardinality
Property cardinalities are indicated, for convenience, using the
following notation and follow the guidance of jCard [RFC7095] and
vCard [RFC6350], which is based on ABNF (see [RFC5234], Section 3.6):
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+-------------+--------------------------------------------------+
| Cardinality | Meaning |
+-------------+--------------------------------------------------+
| 1 | Exactly one instance per jCard MUST be present. |
| *1 | Exactly one instance per jCard MAY be present. |
| 1* | One or more instances per jCard MUST be present. |
| * | One or more instances per jCard MAY be present. |
+-------------+--------------------------------------------------+
10.4. Identification Properties
The following properties, initially defined in [RFC6350], hold the
identity information of the entity associated with the jCard. This
subset of properties selected for this document are relevant to
telephone and messaging applications. jCard is an extensible object;
therefore, there may be future specifications that extend the set of
properties relevant to the applications that implement this
specification.
10.4.1. "fn" Property
The "fn" property provides a formatted text corresponding to the name
of the object the jCard represents. Reference: [RFC6350],
Section 6.2.1.
Value type: A single text value.
Cardinality: 1*
Example:
["fn", {}, "text", "Mr. John Q. Public\, Esq."]
10.4.2. "n" Property
The "n" property provides the components of the name of the object
the jCard represents. Reference: [RFC6350], Section 6.2.2.
Value type: A single structured text value. Each component can have
multiple values.
Cardinality: *1
Example:
["n", {}, "text", "Public;John;Quinlan;Mr.;Esq."]
["n", {}, "text", "Stevenson;John;Philip,Paul;Dr.;Jr.,M.D.,A.C.P."]
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10.4.3. "nickname" Property
The "nickname" property provides the text corresponding to the
nickname of the object the jCard represents. Reference: [RFC6350],
Section 6.2.3.
Value type: One or more text values separated by a COMMA character
(U+002C).
Cardinality: *
Example:
["nickname", {}, "text", "Robbie"]
["nickname", {}, "text", "Jim,Jimmie"]
["nickname", {}, "text", "TYPE=work:Boss"]
10.4.4. "photo" Property
The "photo" property provides image or photograph information that
annotates some aspect of the object the jCard represents. Reference:
[RFC6350], Section 6.2.4.
In addition to the definition of jCard, and to promote
interoperability and proper formatting and rendering of images, the
photo SHOULD correspond to a square image with the size of 128x128,
256x256, 512x512, or 1024x1024 pixels.
Value type: A single URI.
Cardinality: *
Example:
["photo", {}, "uri", "http://www.example.com/jqpublic-256x256.png"]
10.5. Delivery Addressing Properties
This property is concerned with information related to the delivery
address of the jCard object.
10.5.1. "adr" Property
The "adr" property provides the delivery address of the object the
jCard represents. Reference: [RFC6350], Section 6.3.1.
Value type: A single structured text value separated by the SEMICOLON
character (U+003B).
Cardinality: *
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Example:
["adr", {"type":"work"}, "text",
["", "", "3100 Massachusetts Avenue NW", "Washington", "DC",
"20008", "USA"]
10.6. Communications Properties
These properties describe how to communicate with the object the
jCard represents.
10.6.1. "tel" Property
The "tel" property provides the telephone number for the object the
jCard represents. Reference: [RFC6350], Section 6.4.1.
Relative to the SIP From header field value, this information may
provide an alternate telephone number or other related telephone
numbers for other uses.
It is important to note that any of the potential instances of the
"tel" property should not be considered part of the authentication or
verification part of STIR [RFC8224] or required to match the "orig"
claim in the PASSporT [RFC8225]. These telephone numbers can be for
contact, fax, or other purposes aligned with the general usage of
jCard and vCard, but the potential confusion of the callee when
provided with multiple telephone numbers versus the actual, verified
telephone number should be considered from a general policy point of
view.
Value type: By default, it is a single free-form text value (for
backward compatibility with vCard 3), but it SHOULD be reset to a URI
value. It is expected that the URI scheme will be "tel", as
specified in [RFC3966], but other schemes MAY be used.
Cardinality: *
Example:
["tel", { "type": ["voice", "text", "cell"], "pref": "1" }, "uri",
"tel:+1-202-555-1000"]
["tel", { "type": ["fax"] }, "uri", "tel:+1-202-555-1001"]
10.6.2. "email" Property
The "email" property provides the electronic mail address of the
object the jCard represents. Reference: [RFC6350], Section 6.4.2.
Value type: A single text value.
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Cardinality: *
Example:
["email", {"type":"work"}, "text", "jqpublic@xyz.example.com"]
["email", {"pref":"1"}, "text", "jane_doe@example.com"]
10.6.3. "lang" Property
The "lang" property provides the language(s) that may be used for
communicating with the object the jCard represents. Reference:
[RFC6350], Section 6.4.4.
Value type: A single language-tag value.
Cardinality: *
Example:
["lang", {"type":"work", "pref":"1"}, "language-tag", "en"]
["lang", {"type":"work", "pref":"2"}, "language-tag", "fr"]
["lang", {"type":"home"}, "language-tag", "fr"]
10.7. Geographical Properties
These properties provide geographical information associated with the
object the jCard represents.
10.7.1. "tz" Property
The "tz" property provides the time zone of the object the jCard
represents. Reference: [RFC6350], Section 6.5.1.
Note: the reference for time-zone names is https://www.iana.org/time-
zones.
Value type: The default is a single text value. It can also be reset
to a single URI or a UTC-offset value.
Cardinality: *
Example:
["tz", {}, "text", "Raleigh/North America"]
10.7.2. "geo" Property
The "geo" property provides the global positioning of the object the
jCard represents. Reference: [RFC6350], Section 6.5.2.
Value type: A single URI.
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Cardinality: *
Example:
["geo", {}, "uri", "geo:37.386013,-122.082932"]
10.8. Organizational Properties
These properties are concerned with information associated with
characteristics of the organization or organizational units of the
object that the jCard represents.
10.8.1. "title" Property
The "title" property has the intent of providing the position or job
of the object the jCard represents. Reference [RFC6350],
Section 6.6.1.
Value type: A single text value.
Cardinality: *
Example:
["title", {}, "text", "Research Scientist"]
10.8.2. "role" Property
The "role" property has the intent of providing the position or job
of the object the jCard represents. Reference [RFC6350],
Section 6.6.2.
Value type: A single text value.
Cardinality: *
Example:
["role", {}, "text", "Project Leader"]
10.8.3. "logo" Property
The "logo" property has the intent of specifying a graphic image of a
logo associated with the object the jCard represents. Reference
[RFC6350], Section 6.6.3.
Value type: A single URI.
Cardinality: *
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Example:
["logo", {}, "uri", "http://www.example.com/abccorp-512x512.jpg"]
["logo", {}, "uri", "data:image/jpeg;base64,MIICajCCAdOgAwIBAgIC
AQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bm
ljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlvbiBTeXN0
<...the remainder of base64-encoded data...>"]
10.8.4. "org" Property
The "org" property has the intent of specifying the organizational
name and units of the object the jCard represents. Reference
[RFC6350], Section 6.6.4.
Value type: A single structured text value consisting of components
separated by the SEMICOLON character (U+003B).
Cardinality: *
Example:
["org", {}, "text", "ABC\, Inc.;North American Division;Marketing"]
10.9. Explanatory Properties
These properties provide additional information such as notes or
revisions specific to the jCard.
10.9.1. "categories" Property
The "categories" property specifies application category information
about the object the jCard represents. Reference: [RFC6350],
Section 6.7.1.
Value type: One or more text values separated by a COMMA character
(U+002C).
Cardinality: *
Example:
["categories", {}, "text", "TRAVEL AGENT"]
["categories", {}, "text", "INTERNET,IETF,INDUSTRY"]
10.9.2. "note" Property
The "note" property specifies supplemental information or a comment
about the object the jCard represents. Reference: [RFC6350],
Section 6.7.2.
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Value type: A single text value.
Cardinality: *
Example:
["note", {}, "text", "This fax number is operational 0800 to 1715
EST\, Mon-Fri."]
10.9.3. "sound" Property
The "sound" property specifies digital sound content information that
annotates some aspect of the object the jCard represents. This
property is often used to specify the proper pronunciation of the
name property value of the jCard. Reference: [RFC6350],
Section 6.7.5.
Value type: A single URI.
Cardinality: *
Example:
["sound", {}, "uri", "https://www.example.com/pub/logos/abccorp.mp3"]
["sound", {}, "uri", "data:audio/basic;base64,MIICajCCAdOgAwIBAgICBE
AQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bm
ljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlvbiBTeXN0
<...the remainder of base64-encoded data...>"]
10.9.4. "uid" Property
The "uid" property specifies a globally unique identifier
corresponding to the object the jCard represents. Reference:
[RFC6350], Section 6.7.6.
Value type: A single URI value. It MAY also be reset to free-form
text.
Cardinality: *1
Example:
["uid", {}, "uri", "urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6"]
10.9.5. "url" Property
The "url" property specifies a uniform resource locator associated
with the object the jCard represents. Reference: [RFC6350],
Section 6.7.8.
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There are potential security and privacy implications of providing
URLs with telephone calls. The end client receiving a jCard with a
"url" property MUST only display the URL and not automatically follow
the URL or provide automatic preview of the URL, and generally
provide good practices in making it clear to the user it is their
choice to follow the URL in a browser context consistent with all of
the common browser security and privacy practices available on most
consumer OS environments.
Value type: A single uri value.
Cardinality: *
Example:
["url", {}, "uri", "https://example.org/french-rest/chezchic.html"]
10.9.6. "version" Property
The "version" property MUST be included and is intended to specify
the version of the vCard specification used to format this vCard.
Reference: [RFC6350], Section 6.7.9.
Value type: A single text value.
Cardinality: 1
Example:
["version", {}, "text", "4.0"]
11. Extension of jCard
Part of the intent of using jCard is to leverage its extensibility to
define new properties to relay new information related to a caller.
This capability is inherently supported as part of standard
extensibility. However, usage of those new properties should be
published and registered following [RFC7095], Section 3.6 or new
specifications.
12. IANA Considerations
12.1. SIP Call-Info Header Field 'purpose' Parameter Token
This document defines the token "jcard" as a new value for the
'purpose' parameter of the Call-Info header field in the "Header
Field Parameters and Parameter Values" registry defined by [RFC3968].
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+--------------+----------------+-------------------+------------+
| Header Field | Parameter Name | Predefined Values | Reference |
+--------------+----------------+-------------------+------------+
| Call-Info | purpose | Yes | [this RFC] |
+--------------+----------------+-------------------+------------+
12.2. SIP Call-Info Header Field 'call-reason' Parameter
This document defines the 'call-reason' generic parameter for use as
a new parameter in the Call-Info header field in the "Header Field
Parameters and Parameter Values" registry defined by [RFC3968]. The
parameter's token is "call-reason", and it takes the value of a
quoted string.
+--------------+----------------+-------------------+------------+
| Header Field | Parameter Name | Predefined Values | Reference |
+--------------+----------------+-------------------+------------+
| Call-Info | call-reason | No | [this RFC] |
+--------------+----------------+-------------------+------------+
12.3. SIP Call-Info Header Field 'verified' Parameter
This document defines the 'verified' generic parameter for use as a
new parameter in the Call-Info header field in the "Header Field
Parameters and Parameter Values" registry defined by [RFC3968]. The
parameter's token is "verified", and it takes the value of a quoted
string that can only be "true".
+--------------+----------------+-------------------+------------+
| Header Field | Parameter Name | Predefined Values | Reference |
+--------------+----------------+-------------------+------------+
| Call-Info | verified | Yes | [this RFC] |
+--------------+----------------+-------------------+------------+
12.4. SIP Call-Info Header Field 'integrity' Parameter
This document defines the 'integrity' generic parameter for use as a
new parameter in the Call-Info header field in the "Header Field
Parameters and Parameter Values" registry defined by [RFC3968]. The
parameter's token is "integrity", and it takes the value of a quoted
string.
+--------------+----------------+-------------------+------------+
| Header Field | Parameter Name | Predefined Values | Reference |
+--------------+----------------+-------------------+------------+
| Call-Info | integrity | No | [this RFC] |
+--------------+----------------+-------------------+------------+
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13. Security Considerations
Revealing information such as the name, location, and affiliation of
a person necessarily entails certain privacy risks. The SIP Call-
Info header field has no particular confidentiality requirement, as
the information sent in SIP is in the clear anyway. Transport-level
security can be used to hide information from eavesdroppers, and the
same confidentiality mechanisms would protect any Call-Info or jCard
information carried or referred to in SIP.
The security framework of signing and providing integrity to this
data [I-D.ietf-stir-passport-rcd] should be followed, and the use of
constraints and other certificate-based associations should be
considered. This includes considerations for information about the
calling party, which is generally constant, versus per-call data,
which is more transient. This also includes the relationship that
certificates with constraints presents to how they relate to each
other and how that information is managed, protected, and associated
with the correct call corresponding to a calling party.
14. References
14.1. Normative References
[I-D.ietf-stir-passport-rcd]
Wendt, C. and J. Peterson, "PASSporT Extension for Rich
Call Data", Work in Progress, Internet-Draft, draft-ietf-
stir-passport-rcd-26, 5 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-stir-
passport-rcd-26>.
[ISOPNG] ISO/IEC, "Information technology -- Computer graphics and
image processing -- Portable Network Graphics (PNG),
Functional specification, ISO/IEC 15948:2004", March 2004.
[ITUJPEG] ITU-T, "Information technology - Digital compression and
coding of continuous-tone still images, JPEG File
Interchange Format (JFIF) ITU-T Recommendation T.871, ISO/
IEC 10918-5", May 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC2392] Levinson, E., "Content-ID and Message-ID Uniform Resource
Locators", RFC 2392, DOI 10.17487/RFC2392, August 1998,
<https://www.rfc-editor.org/rfc/rfc2392>.
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[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/rfc/rfc3261>.
[RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers",
RFC 3966, DOI 10.17487/RFC3966, December 2004,
<https://www.rfc-editor.org/rfc/rfc3966>.
[RFC3968] Camarillo, G., "The Internet Assigned Number Authority
(IANA) Header Field Parameter Registry for the Session
Initiation Protocol (SIP)", BCP 98, RFC 3968,
DOI 10.17487/RFC3968, December 2004,
<https://www.rfc-editor.org/rfc/rfc3968>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
[RFC6350] Perreault, S., "vCard Format Specification", RFC 6350,
DOI 10.17487/RFC6350, August 2011,
<https://www.rfc-editor.org/rfc/rfc6350>.
[RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095,
DOI 10.17487/RFC7095, January 2014,
<https://www.rfc-editor.org/rfc/rfc7095>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/rfc/rfc7519>.
[RFC7852] Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and
J. Winterbottom, "Additional Data Related to an Emergency
Call", RFC 7852, DOI 10.17487/RFC7852, July 2016,
<https://www.rfc-editor.org/rfc/rfc7852>.
[RFC7903] Leonard, S., "Windows Image Media Types", RFC 7903,
DOI 10.17487/RFC7903, September 2016,
<https://www.rfc-editor.org/rfc/rfc7903>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
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[RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
"Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 8224,
DOI 10.17487/RFC8224, February 2018,
<https://www.rfc-editor.org/rfc/rfc8224>.
[RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
<https://www.rfc-editor.org/rfc/rfc8225>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/rfc/rfc8259>.
[W3C-SVGTiny1.2]
W3C, "Scalable Vector Graphics (SVG) Tiny 1.2", 22
December 2008, <https://www.w3.org/TR/SVGMobile/>.
14.2. Informative References
[RFC2361] Fleischman, E., "WAVE and AVI Codec Registries", RFC 2361,
DOI 10.17487/RFC2361, June 1998,
<https://www.rfc-editor.org/rfc/rfc2361>.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
DOI 10.17487/RFC3325, November 2002,
<https://www.rfc-editor.org/rfc/rfc3325>.
[RFC7340] Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
Telephone Identity Problem Statement and Requirements",
RFC 7340, DOI 10.17487/RFC7340, September 2014,
<https://www.rfc-editor.org/rfc/rfc7340>.
Acknowledgements
We would like to thank David Hancock, Alec Fenichel, Paul Kyzivat, Yi
Jing and other members of the SIPCORE and STIR working groups and
ATIS/SIP Forum IPNNI for their helpful suggestions and comments
during the creation of this document.
Authors' Addresses
Chris Wendt
Somos
United States of America
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Email: chris@appliedbits.com
Jon Peterson
Neustar
United States of America
Email: jon.peterson@neustar.biz
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