ETSI TR 183 057 V2.1.1 (2008-07)

Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Feasibility study on Out-of-band DTMF

DTR/TISPAN-03112-NGN-R2

General Information

• Status: Published
• Publication Date: 21-Jul-2008
• Technical Committee: TISPAN 3 - TISPAN Protocols
• Current Stage: 12 - Completion
• Due Date: 03-Jun-2008
• Completion Date: 22-Jul-2008

Standards Content (Sample)

ETSI TR 183 057 V2.1.1 (2008-07)
Technical Report


Telecommunications and Internet converged Services and
Protocols for Advanced Networking (TISPAN);
Feasibility study on Out-of-band DTMF

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2 ETSI TR 183 057 V2.1.1 (2008-07)



Reference
DTR/TISPAN-03112-NGN-R2
Keywords
DTMF, outband
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© European Telecommunications Standards Institute 2008.
All rights reserved.

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3 ETSI TR 183 057 V2.1.1 (2008-07)
Contents
Intellectual Property Rights.4
Foreword.4
1 Scope.5
2 References.5
2.1 Normative references.5
2.2 Informative references.5
3 Abbreviations.6
4 Introduction and use cases.6
4.1 Introduction.6
4.2 Use cases.7
5 Needs.7
6 Overview of technical solutions.8
6.1 General.8
6.2 DTMF transport along the session signalling path.8
6.3 DTMF transport outside the session signalling path .8
6.3.1 General.8
6.3.2 Use of SIP Event Management capabilities.9
6.3.2.1 Description.9
6.3.2.2 Dialog correlation.10
6.3.2.3 Forking.10
6.3.3 Use of a dedicated control channel .10
7 Comparison of solutions.11
History .12

ETSI

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4 ETSI TR 183 057 V2.1.1 (2008-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Telecommunications and Internet
converged Services and Protocols for Advanced Networking (TISPAN).
ETSI

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5 ETSI TR 183 057 V2.1.1 (2008-07)
1 Scope
The purpose of the present document is to analyse the requirements for out-of-band DTMF transport in IMS, to assess
the possible technical solutions addressing these requirements, to select a solution and to identify and derive the
required changes to the relevant IMS specifications.
NOTE: The consequence of the TR will most certainly lead to developing CRs against ETSI TISPAN Release 2
IMS specifications and the corresponding 3GPP specifications.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI ES 283 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IP Multimedia Call Control Protocol based on Session
Initiation Protocol (SIP) and Session Description Protocol (SDP) Stage 3
[3GPP TS 24.229 (Release 7), modified]".
[i.2] IETF RFC 2833: "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals".
[i.3] IETF RFC 2976: "The SIP INFO Method".
[i.4] IETF RFC 4730: "A Session Initiation Protocol (SIP) Event Package for Key Press Stimulus
(KPML)".
ETSI

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6 ETSI TR 183 057 V2.1.1 (2008-07)
[i.5] 3GPP TR 24.880: "3rd Generation Partnership Project; Technical Specification Group Core
Network and Terminals Media server control using the IP Multimedia (IM) Core Network (CN)
subsystem; Stage 3".
[i.6] draft-mcglashan-mscp-03: "Media Server Control Protocol (MSCP)".
[i.7] draft-ietf-sip-gruu: "Obtaining and Using Globally Routable User Agent (UA) URIs (GRUU) in
the Session Initiation Protocol (SIP)".
[i.8] draft-ietf-sipping-dialogusage: "Multiple Dialog Usages in the Session Initiation Protocol".
[i.9] draft-kaplan-sip-info-events-00: "SIP INFO Event Framework".
[i.10] draft-kaplan-sipping-dtmf-package-00: "DTMF Info-Event Package".
[i.11] http://www1.ietf.org/mail-archive/web/sip/current/msg20982.html.
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AS Application Server
B2BUA Back to Back User Agent
CSCF Call Session Control Function
DTMF Dual Tone Multi Frequency
GRUU Globally Routable UA URI
IMS IP Multimedia Core Network Subsystem
IVR Interactive Voice Response
KPML Key Press Markup Language
MRF Media Resource Function
MSCP Media Server Control Protocol
MSML Media Server Markup Language
NGN Next Generation Network
PSTN Public Switched Telecommunications Network
RTP Real-Time Transport Protocol
SDP Session Description Protocol
SIP Session Initiation Protocol
UA User Agent
UE User Equipment
URI Uniform Resource Identifier
XML eXtended Markup Language
4 Introduction and use cases
4.1 Introduction
The TISPAN Release 1 set of standards supports transport of DTMF using in-band signals in the form of RTP packets.
The actual waveforms may be encoded using a voice codec (e.g. G.711) or represented using a dedicated format defined
in RFC 2833 [i.2].
In-band transport provides a suitable solution to cover all use cases where DTMF has to be exchanged within the
framework of an established media link between two entities. This typically occurs when the user explicitly connects to
a DTMF-driven menu (e.g. voicemail browsing, televoting, etc.) or when a call is directed to an intermediary entity
(e.g. an MRF) so that a user interaction procedure can take place prior to completing the establishment of the call
(e.g. credit card calling).
ETSI

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7 ETSI TR 183 057 V2.1.1 (2008-07)
However, this solution is far less suitable when DTMF is used as a means to invoke a particular feature in a network
entity that has no inherent reason for being in the media path at the moment this feature is invoked. Although the
network entity could be artificially inserted (maintained) in the media path (using e.g. conferencing capabilities) for the
purpose of collecting DTMF, an "out of band" transport mechanism would definitely provide a more efficient solution.
In the context of the present document, "Out-of-band" transport of DTMF should be understood as means to transport,
outside the media path, signals representing key press stimuli.
4.2 Use cases
The need for an "out of band" transport mechanism has been identified in the framework
...