Internet Engineering Task Force
Internet Draft Koetter
draft-koetter-cpl-network-00.txt
February 17, 2002
Expires: August 16, 2002
CPL Extensions for Network Operators
1. STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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2. Abstract
The Call Processing Language (CPL) can be used to describe and
control Internet telephony services. The original CPL
specification focuses on call handling on network servers. The
extensions of CPL in this document are designed to add
capabilities to describe network-operator-related services. These
services are essential for providing services on a network.
Further networks features have to be definded before network
operators have got a sufficient toolset. Here two features will be
introduced. These are televote and lawful interception.
3. Introduction
The current CPL [1] specification focuses on the server side call
handling. It does not support network-operator related services.
We can either create a new language or extend CPL to provide such
support. Extending CPL is a better choice for two reasons. First,
many existing CPL components can be re-used. Second, the
network-operator features can influence call handling which has
been defined in the current CPL specification.
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The CPL extensions for network-operators are not tied to any
particular protocol.
4. Conventions of This Document
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALLNOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [2]
and indicate requirement levels for compliant CPL implementations.
In examples, non-XML strings such as -action1- and so forth, are
sometimes used. These represent further parts of the script which
are not relevant to the example in question.
Some paragraphs are indented, like this; they give
motivations of design choices, or questions for future
discussion in the development of the CPL extensions, and
are not essential to the specification of the language.
5. Overview of the Extensions
We define two kinds of extensions. These are all sub-level actions.
The actions provide benefit for network operators. The actions are
namely "televote" and "lawful interception".
In the case the owner of an IP network can interconnect with other
networks as well as not doing so and offering gateways to traditional
telephony networks. For these different infrastructures the network
provider needs tools in order to offer different services to
different users.
Network operators need more features in order to offer telephony over
IP networks and being able to do billing, restrictions or new
services. It should also be assured that the user MUST NOT be able
to overcome restrictions of the network operators.
Further features for network operators can be CLIP (Call
Line Identification Restriction) and CLIR (Call Line
Identification Presentation) as well as the limitation of
numbers and services. Completely new services may also be
the authentification by password at the server when calling
or called, location based services, and message services to
other networks like SMS (short message service).
6. Namespace of CPL extensions for network-operators
The namespace of the CPL extensions for network-operators
will be "http://www.rfc-editor.org/rfc/rfcxxxx.txt" and will
be declared as xmlns:network. Figure 1 shows the example of
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using namespace declaration of CPL extensions for network-
operators.
7. New sub-level actions
We still keep 'incoming' and 'outgoing' as the top-level
actions. We create a new kind of actions named sub-level
actions to hold the CPL extensions. The sub-level action
defines a lower-level tag of the top-level action. We add
two sub-level actions for CPL extensions for network-
operators.
Figure 1: Namespace declaration of CPL extensions for
network-operators
Tag: cpl
Parameters: None
Sub-tags: ancillary See CPL Section 10
subaction See CPL Section 9
network:lawfulintercept sub level action for lawful
call interception.
network:televote sub level action for televote
outgoing Top-level actions to take on outgoing calls
incoming Top-level actions to take on incoming calls
Figure 2: Syntax of the extended CPL node
8. New network operator features
Here only two new features are introduces. As mentioned for a
complete network tool set more features are needed. They should be
defined in later version of this
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8.1 Lawful interception
The feature network:lawfulintercept, the action performed when the
network operator wants to intercept the conversation. The operator
may define how he wants the interception to happen and what device
will be used.
Node: lawfulintercept
Outputs: None
Parameters: method method to intercept the call
destination address of intercepting device
Figure 3: Syntax of lawful interception node
8.2 Syntax of the extended CPL node Televote
The second subaction is network:televote, the action performed when a
network operator wants to do a televoting. Televoting contains a
number of parameters that specify the usage. In the CPL engine the
televote action should be realised with as little use of resources as
possible. Televoting processes in traditional telephony may cause an
avalanche of calls in a short period of time. The CPL server should
be enabled to be able to cope with those. The network:televote
subaction has got the parameter endmode that specifies when the
current cpl script should be read again.
Node: televote
Outputs: None
Parameters: starttime start time of televote process
stoptime stop time of televote process
duration duration of televote process
endmode defines the end mode
mode defines the selection mode
n defines probability or nth
submissionmode defines mode of submission
submissionaddress address for result submission
winnermode direction mode for successful
winneraddress address if successful
Figure 4: Syntax of the televote node
9. Examples
The examples should show how the features could be used.
9.1 Lawful interception
The script in Figure 5 is a script that provides a lawful call
interception for all incoming calls.
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method="IP"
destination= "129.130.131.132">
Figure 5: Example script: Lawful interception
9.2 Televote
The script in Figure 6 is a script that does a televoting
session. The session starts on the 31st of October 2002 at 13:30 and
has the duration of one hour. The calls should be counted and the
1000th caller will be redirected to sip:winnerphone@destination.com.
The result of televote will be submitted by electronic mail to
customer@destinastion.com. The result should contain at least the
number of incoming calls but could include more depending on CPL
engine realisation.
Figure 6: Example script: Televote
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10. The XML DTD of the CPL extensions for network oprators
The XML DTD of the CPL extensions for network-operators follows the
XML DTD of CPL with some modifications on the sub-level actions.
We avoid repeating the parts that are the same as those in XML DTD
for CPL in this document. Only the new added definitions are listed
here.
Figure 7: DTD lawful interception
Figure 8: DTD televote
11. ESSENTIAL REMARK FOR FURTHER USE
This paper was written during in the circumstances of a final degree
thesis at the University of Stuttgart in the IND. It means that I
will most probably not be working on this subject in the future. Due
to this the paper is open for modifications. If changed please submit
one copy to my mentioned email address.
If parts of this document are kept in further versions please keep
the names in the authors list.
An implementation of the features televote and lawful interception
does exist at
Siemens AG, ICN WN CC NA A 19, Hofmannstr. 51, 81559 Munich, Germany.
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12. Authors' Addresses
Stephan Koetter
electronic mail: stephan.koetter@web.de
13. Bibliography
[1] J. Lennox and H. Schulzrinne, "CPL: a language for user control
of internet telephony services," Internet Draft, Internet Engineering
Task Force, July 2000. Work in progress.
[2] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," Request for Comments 2119, Internet Engineering Task Force,
Mar. 1997.
[3] M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg,
"SIP: session initiation protocol," Request for Comments 2543,
Internet Engineering Task Force, Mar. 1999.
[4] R. Sparks, "SIP call control," Internet Draft, Internet
Engineering Task Force, Feb. 2001. Work in progress.
Full Copyright Statement
Copyright (c) The Internet Society (2001). All Rights Reserved.
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Table of Contents
1. STATUS OF THIS MEMO 1
2. ABSTRACT 1
3. INTRODUCTION 1
4. CONVENTIONS OF THIS DOCUMENT 2
5. OVERVIEW OF THE EXTENSIONS 2
6. NAMESPACE OF CPL EXTENSIONS FOR NETWORK-OPERATORS 2
7. NEW SUB-LEVEL ACTIONS 3
8. NEW NETWORK OPERATOR FEATURES 3
8.1 LAWFUL INTERCEPTION 4
8.2 SYNTAX OF THE EXTENDED CPL NODE TELEVOTE 4
9. EXAMPLES 4
9.1 LAWFUL INTERCEPTION 4
9.2 TELEVOTE 5
10. THE XML DTD OF THE CPL EXTENSIONS FOR NETWORK OPRATORS 6
11. ESSENTIAL REMARK FOR FURTHER USE 6
12. AUTHORS' ADDRESSES 7
13. BIBLIOGRAPHY 7
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