DISPATCH R. Avasarala, Ed.
Internet-Draft Motorola Inc
Intended status: Informational R. Jesske
Expires: November 14, 2010 Deutsche Telekom
May 13, 2010
A Session Initiation Protocol (SIP) Event Package for Communication
Barring Notification Information in support of the Dynamic Incoming
Communication Barring (ICB) Notification service
draft-avasarala-dispatch-comm-barring-notification-00.txt
Abstract
3GPP is defining the protocol specification for the Communication
Barring (CB) service using IP Multimedia (IM) Core Network (CN)
subsystem supplementary service and more particularly the dynamic
incoming communication barring service. As part of dynamic incoming
communication barring (ICB) service, a SIP based Event package
framework is used for notifying users about communication barrings
(dynamic and rule based) of their incoming communication sessions.
This document proposes a new SIP event package for allowing users to
subscribe to and receive such notifications. Users can further
define filters to control the rate and content of such notifications.
The proposed event package is applicable to the ICB supplementary
service in IMS and may not be applicable to the general internet.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 November 14, 2010.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 4
4. Abbreviations and Definitions . . . . . . . . . . . . . . . . 5
4.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5
5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Package Definition . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 6
6.2. Event Package Parameters . . . . . . . . . . . . . . . . . 6
6.3. SUBSCRIBE bodies . . . . . . . . . . . . . . . . . . . . . 6
6.4. Subscription Duration . . . . . . . . . . . . . . . . . . 7
6.5. Notify bodies . . . . . . . . . . . . . . . . . . . . . . 7
6.6. Notifier Processing of SUBSCRIBE requests . . . . . . . . 7
6.6.1. Authentication . . . . . . . . . . . . . . . . . . . . 8
6.6.2. Authorization . . . . . . . . . . . . . . . . . . . . 8
6.7. Notifier Generation of NOTIFY requests . . . . . . . . . . 8
6.8. Subscriber Processing of NOTIFY Requests . . . . . . . . . 9
6.9. Handling of Forked Requests . . . . . . . . . . . . . . . 9
6.10. Rate of Notifications . . . . . . . . . . . . . . . . . . 9
6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 9
7. Comm-bar-info Document . . . . . . . . . . . . . . . . . . . . 9
8. Structure of Comm-bar-info Format . . . . . . . . . . . . . . 10
8.1. Comm-bar-info Element . . . . . . . . . . . . . . . . . . 10
8.1.1. comm-block-subs-info Element . . . . . . . . . . . . . 10
8.1.2. Comm-bar-ntfy-info Element . . . . . . . . . . . . . . 12
8.1.3. Comm-bar-info-selection-criteria . . . . . . . . . . . 13
8.2. Sample Notification body . . . . . . . . . . . . . . . . . 13
8.2.1. Instance of communication barring subscription
filter document . . . . . . . . . . . . . . . . . . . 13
8.2.2. Instance of communication barring notification
document . . . . . . . . . . . . . . . . . . . . . . . 14
8.3. Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
10.1. Communication Barring Information Event Package
Registration . . . . . . . . . . . . . . . . . . . . . . . 20
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
12.1. Normative References . . . . . . . . . . . . . . . . . . . 21
12.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Change log . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
3GPP is currently maintaining and specifying incoming communication
barring mechanisms which allow users to dynamically block incoming
communications from callers whom they consider as unwanted or
unsolicited. The intention of such mechanisms is to provide users
with sufficient flexibility to manage their incoming communications
in a better way. The most common example is the Anonymous
Communication Rejection (ACR) where in the incoming communications
from senders whose identity is marked as "Anonymous" is rejected.
Similarly other variants of ICB include dynamically blocking a
particular caller by the subscribers, called the dynamic ICB which is
specified in 3GPP specification [1].
However, with the increasing number of unwanted calls and increased
usage of incoming communication barring services, users may have lot
of callers being blocked from time to time and for different periods
based on temporary or permanent block. For instance, a user may have
blocked a particular caller for a temporary period and specified the
period as 1 year. Though there are ways by which users can keep
track of their communication barrings, there is no efficient
mechanism for the users to get information of their communication
barrings that get enacted in the network. This information would
help them to verify their rules and rectify if required.
This document defines a SIP event package that allows a SIP User
Agents to subscribe to and be notified of communication barrings
enacted on their behalf.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [2] and
indicate requirement levels for compliant implementations.
3. Applicability Statement
It is believed that the SIP event package defined here is not
applicable to the general Internet and has been designed to serve the
architecture of the ICB services in IMS core networks. The aim of
this memo is to follow the procedure indicated in RFC 5727 [3] and to
register a new event package with event name "comm-bar-info" with
IANA.
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4. Abbreviations and Definitions
4.1. Abbreviations
ACR: Anonymous Communication Rejection
CB: Communication Barring.
ICB: Incoming Communication Barring
ICBN: Incoming Communication Barring Notification.
IMS: IP Multimedia System
4.2. Definitions
Subscriber - The User Agent who has subscribed to the
Communication Barring notification service.
User - Another term for the subscriber.
Originating User - The User Agent who is the originator of the
incoming communication, which was initially targeted towards the
Diverting User, but finally sent to the Diverted-To User. The
Originating User is also referred to as the Caller.
IMS Core Network - This refers to the IMS based SIP based network
that conforms to the [7] and not the general SIP network as
defined in [4].
5. Requirements
A comprehensive description of all the requirements that affect the
ICB service developed by 3GPP can be found in the 3GPP specification
[5].
For the sake of simplicity, we briefly discuss here those
requirements that affect the solution described in this document.
These requirements can be summarized as follows:
o There must be a mechanism that allows subscribers to block certain
categories of incoming communications
o There must be a mechanism that allows terminating users to
register unwanted callers within the network.
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o There must be a mechanism that allows terminating users to block
unwanted callers either permanently or for a temporary period or
for a maximum lifetime which is set by the network operator.
o There must be a mechanism that enables filtering of notifications
of communication blocking.
o There must be a mechanism that enables triggering of notifications
of communication blocking.
o There must be a mechanism that enables selecting information to be
included in notifications of communication barring.
These requirements lead to a solution whereby the user can indicate
to a network node his interest in receiving certain type of
notifications of communication blocking. Pushing these settings to a
network node allows the network node to conserve scarce resources
while still notifying the user of communication barrings enacting on
the user's behalf.
6. Package Definition
This section fills in the details needed for an event package as
defined in Section 4.4 of [6].
6.1. Event Package Name
The SIP Events specification requires package definitions to specify
the name of their package or template-package.
The name of this package is "comm-bar-info". As specified in [6],
this value appears in the Event header present in SUBSCRIBE and
NOTIFY requests.
6.2. Event Package Parameters
The SIP Events specification [6] allows packages to define additional
parameters. This event package "comm-bar-info" does not define
additional parameters.
6.3. SUBSCRIBE bodies
The SIP Events specification requires package or template-package
definitions to define the usage, if any, of bodies in SUBSCRIBE
requests.
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A SUBSCRIBE for Communication Barring event MAY contain a body. The
purpose of the body depends on its type. Subscriptions to the Comm-
block-info event package SHALL only include a body of MIME type
"application/comm-bar-info+xml".
A body of the SUBSCRIBE request with content type set to MIME type
"application/comm-bar-info+xml" contains information about the
communication barring notification information filter criteria and
notification trigger criteria. This information is conveyed using
the XML elements defined in Section 8.1.1.1.
6.4. Subscription Duration
The default expiration time for subscriptions within this package is
3600 seconds. As per [6], the subscriber MAY specify an alternate
expiration in the Expires header field.
6.5. Notify bodies
The SIP Events specification requires package definitions to define a
default value for subscription durations, and to discuss reasonable
choices for durations when they are explicitly specified.
The NOTIFY message contains bodies. This body is a format listed in
the Accept header field of the SUBSCRIBE request or a package
specific default format if the Accept header field was omitted from
the SUBSCRIBE request.
In this event package, the body of the notification contains the
communication barring information pertaining to the barring that
occurred in the network on behalf of the subscriber. The format of
the communication barring information is an XML document as per
elements defined in Section 8.1.2. See Section 8.
All subscribers and notifiers of the "comm-bar-info" event package
MUST support the "application/comm-bar-info+xml" data format
described in Section 8. The SUBSCRIBE request MAY contain an Accept
header field. If no such header field is present, it has a default
value of "application/comm-bar-info+xml" (assuming Event header has a
value of "comm-bar-info"). If the Accept header field is present, it
MUST contain the value "application/comm-bar-info+xml".
6.6. Notifier Processing of SUBSCRIBE requests
The contents of a document containing comm-bar-info information can
contain sensitive information that can reveal some privacy
information. Therefore, such comm-bar-info documents MUST only be
sent to authorized subscribers. In order to determine if a
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subscription originates in an authorized user, the subscriber MUST be
authenticated as described in Section 6.6.1 and then the user MUST be
authorized to be a subscriber as described in Section 6.6.2.
6.6.1. Authentication
Notifiers MUST authenticate all subscription requests. This
authentication can be done using any of the mechanisms defined in [4]
and other authentication extensions.
6.6.2. Authorization
Once authenticated, the notifier makes an authorization decision. A
notifier MUST NOT accept a subscription unless authorization has been
provided by the user. The means by which authorization are provided
are outside the scope of this document. Authorization may have been
provided ahead of time through access lists, perhaps specified in a
web page. Authorization may have been provided by means of uploading
some kind of standardized access control list document
6.7. Notifier Generation of NOTIFY requests
The SIP Events specification details the formatting and structure of
NOTIFY messages. However, packages are mandated to provide detailed
information on when to send a NOTIFY, how to compute the state of the
resource, how to generate neutral or fake state information, and
whether state information is complete or partial. This section
describes those details for the "comm-bar-info" event package.
A notifier MAY send a NOTIFY at any time. Typically, it will send
one when a communication barring is enacted on behalf of the user.
The NOTIFY request MAY contain a body containing a comm-bar-info
document. The times at which the NOTIFY is sent for a particular
subscriber, and the contents of the body within that notification,
are subject to any rules specified by the authorization policy that
governs the subscription and to preferences indicated at the time of
subscription.
The body of the NOTIFY MUST be sent using the type "application/
comm-bar-info+xml".
It is RECOMMENDED that the notifiers do maintain the history of last
N communication barrings that occurred, where the value N >=1 as part
of state information for that server. The value of N could be
configured and is left to server policy to determine appropriate
value.
The state information is retained even after the notification for
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those barrings are sent to the subscriber and changes when new
barring occurs. So every time a new barring occurs, the state
information changes to reflect the latest barring removing the oldest
barring information.
6.8. Subscriber Processing of NOTIFY Requests
The SIP Events specification expects event packages to describe the
process followed by the subscriber upon receipt of a NOTIFY request.
In this specification, each NOTIFY request contains a comm-bar-info
document
6.9. Handling of Forked Requests
The SIP Events specification requires each package to describe
handling of forked Requests.
This specification only allows a single dialog to be constructed as a
result of emitting an initial SUBSCRIBE request. This guarantees
that only a single notifier is generating notifications for a
particular subscription to a particular user.
6.10. Rate of Notifications
The SIP Events specification requires each package to specify maximum
rate at which notifications can be sent .
Comm-bar-info notifiers SHOULD NOT generate notifications for a
single subscription at a rate of more than once every five seconds.
6.11. State Agents
The notifers maintain the state of last N communication barrings,
where N>=1 that occurred in the network on behalf of the subscriber
even after the notifications for those N communications barrings are
sent or unsent. This state information gets updated with the latest
communication barring that occurs by removing the oldest
communication barring and adding the latest barring while maintaining
the number of barrings at N.
Thus at any point of time a subscriber MAY know the state of
communication barrings enacted on his or her behalf by the server.
7. Comm-bar-info Document
Comm-block-info document is an XML document [8] that MUST be well-
formed and SHOULD be valid. Communication Barring Information
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documents MUST be based on XML 1.0 and MUST be encoded using UTF-8
[9].
8. Structure of Comm-bar-info Format
A Communications Barring Information document starts with a "comm-
bar-info" element. The comm-bar-info element has a series of
elements describing the particular communication barring or the
filter criteria for receiving the communication barring information.
8.1. Comm-bar-info Element
The comm-bar-info element gives information about the specific
communication barring or it could give information about a particular
selection criteria for the user receiving the communication barring
information.
8.1.1. comm-block-subs-info Element
The comm-block-subs-info element is used by the subscribing user to
specify the communication barring information selection criteria and
the communication barring notification trigger criteria. It contains
the following elements:
8.1.1.1. comm-bar-selection-criteria
This element contains information about communication barring
information selection criteria. It contains following sub-elements
for specifying the selection criteria.
8.1.1.1.1. originating-user-selection-criteria
This element specifies the originating user information for the
communication i.e. the caller. This is specified in the form of
"user-name" and "user-uri". E.g. sip:Alice@domain.com. The Username
as well as User-URI specified will be compared with the originating
user information of the current user and if there is a match, then
information about the barring of this specific communication would be
selected for notification to the Diverting user. It consists of the
following sub-elements.
8.1.1.1.1.1. user-info
This element gives user details like username and URI. This element
has further sub-elements for describing username and user URI
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8.1.1.1.1.1.1. User-name
This element gives Username. "Alice".
8.1.1.1.1.1.2. User-URI
This element gives User URI. E.g "sip:Alice@domain.com". It takes
the form of any URI scheme like sip. sips, tel or any other URI
scheme
8.1.1.1.2. barring-type-selection-criteria
This element specifies the type of barring set by the user. This
element can have 2 values: temporary and permanent. The value
temporary means that the caller identity is barred for a temporarty
period specified by the user. The value permanent means that the
caller identity is blocked for ever.
8.1.1.1.3. barring-time-selection-criteria
This element specifies the time range for receiving notifications.
It contains following additional elements .
8.1.1.1.3.1. time-range
This element specifies the time range at which notifications for
communication barrings can be sent to the subscriber. This could be
specified in the form of a time-interval to enable periodic
triggering of notifications of communication barrings which took
place in that time-interval.
NOTE: If the time-range element is not specified, then notifications
about every communication barring that occurs is sent to the
subscriber.
8.1.1.1.3.1.1. start-time
This element specifies the start time for receiving notifications.
Its value is expressed in YYYY:MM:DDTHH:MM:SSZ format.
8.1.1.1.3.1.2. end-time
This element specifies the end time for receiving notifications. Its
value is expressed in YYYY:MM:DDTHH:MM:SSZ format.
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8.1.1.1.4. barring-reason-selection-criteria
This element contains the reason for communication barring. It
contains following sub-element:
8.1.1.1.4.1. barring-reason-info
This element gives the actual reason for the communication barring.
E.g. "ACR".
8.1.1.2. comm-block-ntfy-trigger-criteria
8.1.1.2.1. notification-time-selection-criteria
This element informs the server about the time at which the
notification should be triggered.
8.1.1.2.2. presence-status-selection-criteria
This element gives the presence status of the subscriber, based on
which the decision can be made, whether the subscriber wishes to
receive notification information or not.
8.1.1.2.2.1. presence-selection-info
This element specifies the presence status of the subscriber within
which the subscriber expects to receive notifications about
communication barrings.
8.1.2. Comm-bar-ntfy-info Element
This element gives the notification information. This element has
following sub-elements:
8.1.2.1. originating-user-info
Refer to Section 8.1.1.1.1 for details of this element.
8.1.2.2. barring-time-info
This element gives the time of communication barring. Its value is
expressed in YYYY:MM:DDTHH:MM:SS format.
8.1.2.3. barring-reason-info
This element gives the actual reason for the communication barring.
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8.1.3. Comm-bar-info-selection-criteria
This element gives the subscriber various to select communication
barring information. This element has following sub-elements.
8.1.3.1. disable-originating-user-info
This element gives the subscriber option of adding originating user
information to the notification information. The default value is
false which means the subscriber wants the originating-user-info
element to be present in the notification information.
8.1.3.2. disable-barring-type
This element gives the subscriber option of adding barring-type
information to the notification information. The default value is
false which means the subscriber wants the barring-type information
to be present in the notification information.
8.1.3.3. disable-barring-reason
This element gives the subscriber option of adding barring-reason
information to the notification information. The default value is
false which means the subscriber wants the barring-reason information
to be present in the notification information.
8.1.3.4. disable-barring-rule
This element gives the subscriber option of adding barring-rule
information to the notification information. The default value is
false which means the subscriber wants the barring-rule information
to be present in the notification information.
8.2. Sample Notification body
8.2.1. Instance of communication barring subscription filter document
The communication barring notification document instance shown below
is the notification information for communication barring that
occurred at 10AM as per the rule that says all communications from
Telemarketer as Originating user should be blocked permanently.
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Telemarketer
sip:Telemarketer@xyz-service.com
Permanent
2010:03:20::T10:00:00Z
0
ACR
1999-05-31T13:20:00-05:00Z
2006-05-06T13:20:00-05:00Z
8.2.2. Instance of communication barring notification document
The communication barring notification document instance shown below
is the notification information for communication barring that
occurred at 9.20AM as per the rule that says all communications
should be blocked from 9 AM to 10 AM everyday.
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Telemarketer
sip:Telemarketer@xyz-service.com
Temporary
T9:20:00Z
T9:00:00Z
T10:00:00Z
,/barring-time-range>
RULE
8.3. Schema
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9. Security Considerations
Authentication and authorization of subscriptions have been discussed
in Section 6.6. Lack of authentication or authorization may provide
comm-bar-info information to unauthorized parties and can reveal
sensitive information with regards to the user's call receiving
patterns. For example, who calls the user and at what time, etc.
Integrity protection and confidentiality of notifications are also
discussed in Section 6.7. If a notifier does not encrypt bodies of
NOTIFY requests, an eavesdropper could learn the status of a SIP user
agent and use it to create malicious sessions. If the notifier does
not integrity protect the bodies of NOTIFY requests, a man-in- the-
middle attacker or malicious SIP proxy could modify the contents of
the comm-bar-info event package notification. Although this does not
cause harm, it can create annoyances.
10. IANA Considerations
This document registers the new SIP Event Package.
10.1. Communication Barring Information Event Package Registration
Package Name: Comm-bar-info
Type: Package
Contact: Jon Merdith,
Published Specification: RFC XXXX (Note to RFC Editor)
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11. Acknowledgements
The authors would like to thank Samir Saklikar and Subir Saha for
being part of the initial discussions and Ban Al-Bakri for her
valuable comments and suggestions.
12. References
12.1. Normative References
[1] 3GPP, "Anonymous Communication Rejection (ACR) and Communication
Barring (CB) using IP Multimedia (IM) Core Network (CN)
subsystem; Protocol specification", 3GPP TS 24.611 8.2.0,
December 2008.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[3] Peterson, J., Jennings, C., and R. Sparks, "Change Process for
the Session Initiation Protocol (SIP) and the Real-time
Applications and Infrastructure Area", BCP 67, RFC 5727,
March 2010.
[4] 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.
[5] 3GPP, "IP Multimedia Core Network Subsystem (IMS) Multimedia
Telephony Service and supplementary services; Stage 1", 3GPP
TS 22.173 10.2.0, March 2010.
[6] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
12.2. Informative References
[7] 3GPP, "IP multimedia call control protocol based on Session
Initiation Protocol (SIP) and Session Description Protocol
(SDP); Stage 3", 3GPP TS 24.229 5.23.0, September 2009.
[8] Maler, E., Sperberg-McQueen, C., Paoli, J., and T. Bray,
"Extensible Markup Language (XML) 1.0 (Second Edition)", World
Wide Web Consortium FirstEdition REC-xml-20001006, October 2000,
.
[9] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., Polk,
J., and J. Rosenberg, "Common Policy: A Document Format for
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Expressing Privacy Preferences", RFC 4745, February 2007.
Appendix A. Change log
[RFC EDITOR NOTE: Please remove this section when publishing]
Authors' Addresses
Ranjit Avasarala (editor)
Motorola India Pvt Ltd
Bagamane Tech Park, C V Raman Nagar
Bangalore 560093
India
Email: ranjit@motorola.com
Roland Jesske
Deutsche Telekom
Heinrich-Hertz-Strasse 3-7
Darmstadt 64307
Germany
Email: r.jesske@telekom.de
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