SIST ETS 300 334 E1:2003

• Abstract:

  This standard will give guidance on call routing for the ISDN services covered by ISUP version 2

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 334 ed.1 (1995-12) - Integrated Services Digital Network (ISDN); Signalling System No.7; Routeing in support of ISDN User Part (ISUP) version 2 services

SIST ETS 300 334 E1:2003 is the Slovenian adoption of ETS 300 334 Edition 1 from the European Telecommunications Standards Institute (ETSI). It gives guidance on international call routeing for Integrated Services Digital Network (ISDN) services implemented with Signalling System No.7 ISDN User Part (ISUP) version 2. It is written for network operators, routeing engineers, and planners who need to choose paths at international gateways and transit exchanges.

What does SIST ETS 300 334 E1:2003 specify?

SIST ETS 300 334 E1:2003 specifies how to support ISDN call routeing when ISUP version 2 is used in the international network. The document is focused on practical route selection for international gateways, international transit exchanges, and network planning.

The standard is organized into:

• scope and references
• abbreviations
• additions and clarifications to CCITT Recommendation E.172
• additional routeing information for parameters
• interworking and fallback effects on routeing
• path selection and traffic distribution
• informative annexes with examples, background material, and bibliography

It also says that CCITT Recommendations E.170 and E.171 need to be considered alongside this ETS.

What are the key requirements of SIST ETS 300 334 E1:2003?

SIST ETS 300 334 E1:2003 builds on CCITT Recommendation E.172 and adds routeing guidance for ISDN in Europe. The main practical message is that routeing decisions should preserve the right bearer capability, signalling capability, and propagation-delay performance as far as possible.

Transmission Medium Requirement (TMR) handling

Clause 5.1 says that one TMR value shall be used for a specific service request across the international network and across internetwork boundaries. The TMR value should only change when fallback occurs. In practice, this means routeing systems should keep the bearer requirement stable as the call crosses networks, so the chosen path matches the requested service.

The clause also recommends that national networks use the same TMR values as the international network. If conversion from requested service to TMR is not done in the originating local exchange, the TMR shall be available at the outgoing international gateway and forwarded onward if possible.

New TMR value for preferred fallback

Clause 5.1.1 introduces the TMR value “64 kbit/s unrestricted preferred”. It marks cases where fallback from 64 kbit/s unrestricted to speech or 3,1 kHz audio is allowed. If no route supports that TMR value at an interworking point, the fallback procedure should happen there.

This matters because the network can still complete the call on a lower-capability bearer when the preferred 64 kbit/s route is not available.

Multirate connections

Clause 5.1.2 treats multirate connections as multiple circuit-switched connections with bandwidth between 128 kbit/s and 1 920 kbit/s. These connections are restricted to 2 Mbit/s systems, and the relevant TMR values are identified in ETS 300 356-1.

For planners, this means multirate services must be matched with routes and interworking points that can actually support the required bearer structure.

ISUP Preference Indicator (IPI)

Clause 5.3 applies the ISUP Preference Indicator (IPI) criteria to ISDN services. If an incoming address message says “required” or “preferred” and more than one route exists, the route with ISUP version 2 capability should be selected if possible.

The same clause says the most restrictive IPI value shall be used when several services are requested together. It also assigns:

• ISUP required to services such as CUG without outgoing access, essential user-to-user signalling services 2 and 3, and add-on-conference
• ISUP preferred as the minimum for calls initiated by ISDN subscribers
• ISUP not required for calls originating in the PSTN

In practice, IPI helps routeing systems choose paths that can carry the signaling features the call needs.

Propagation delay and route choice

Clause 5.4 says propagation delay (PD) shall be considered per call at incoming, outgoing, and transit International Switching Centres (ISCs). If PD is greater than 70 ms, or the satellite indicator is set, routes with the least possible transmission delay are preferred.

The practical effect is that routeing should avoid long-delay paths when the call history shows high delay. The clause also allows digital-capable routes to be preferred among routes with similar delay, which helps reduce quality loss.

Digital Circuit Multiplication Equipment (DCME)

Clause 5.5 says DCME links should be avoided where they would add clipping. For international incoming and outgoing calls, national links with DCME should be avoided. For transit traffic, routes with DCME should be avoided except on the last international link.

If the destination is a digital mobile network and can be identified from the first three digits of the national number, DCME routes should be avoided all the way. In practice, this is a quality-of-service rule meant to reduce stacked clipping and improve speech quality.

Interworking, fallback, and traffic distribution

Clause 6 explains that ISDN and PSTN services must interwork, and terminal interworking within ISDN is also fundamental. If an incoming call is incompatible with the destination terminal capability, fallback should occur if possible; otherwise the call is released.

Clause 7 gives guidance on separating ISDN and PSTN traffic when carriers offer different facilities. It says traffic distribution should be agreed separately for ISDN and PSTN traffic, and the routeing function should be logically separated from the distribution function. This helps avoid avoidable call failures when different carriers support different signaling or bearer capabilities.

What terms does SIST ETS 300 334 E1:2003 define?

SIST ETS 300 334 E1:2003 uses a small set of routeing terms that are central to its guidance.

• ISDN (Integrated Services Digital Network) - the digital network environment for the services covered by this ETS.
• ISUP (ISDN User Part) - the Signalling System No.7 part used for call control and related signaling.
• TMR (Transmission Medium Requirement) - the routeing parameter that expresses the bearer requirement of the call.
• IPI (ISUP Preference Indicator) - the indicator used to show whether ISUP capability is required, preferred, or not required.
• PD (Propagation Delay) - the one-way delay that influences route selection.
• PDC (Propagation Delay Counter) - the counter already used for echo control and also evaluated here for routeing.
• DCME (Digital Circuit Multiplication Equipment) - equipment that can introduce clipping and therefore affects route choice.
• MOC (Mobile Originated Call) - a call originating from a mobile network, treated specially when delay is high.

Who uses SIST ETS 300 334 E1:2003?

SIST ETS 300 334 E1:2003 is used by organizations that design, operate, or plan international ISDN routeing. Typical users include:

• international gateway operators
• international transit exchange operators
• network planning teams
• signalling and routeing engineers
• service planners handling ISDN/PSTN interworking
• carriers and administrations that distribute traffic across different links

These users apply the standard when deciding which route can carry a call, which capabilities must be preserved, and when fallback or traffic separation is appropriate.

Which standards are used with SIST ETS 300 334 E1:2003?

SIST ETS 300 334 E1:2003 is built around these referenced documents:

Standard	What it contributes
CCITT Recommendation E.172	The base ISDN routing plan that this ETS clarifies and extends.
ETS 300 100	Routeing support for ISUP version 1, used as the earlier related ETS.
ETS 300 356-1	ISUP version 2 basic services for the international interface, including parameter procedures used by this ETS.
CCITT Recommendation E.170	General traffic routing principles that the scope says should also be considered.
CCITT Recommendation E.171	The international telephone routing plan that should also be considered.

What does the SIST ETS 300 334 E1:2003 document contain?

The document contains clause-level guidance, tables, a figure, and informative annexes. Clause 5 includes the main routeing rules for TMR, IPI, propagation delay, and DCME effects.

It includes:

• Table 1 mapping requested ISDN services to TMR values
• Table 2 showing allowed interworking cases between incoming and outgoing services
• Figure 1 showing a functional model for separating ISDN and PSTN traffic and distributing it across carriers
• Annex A with examples of how PD and DCME affect routeing
• Annex B with background on propagation delay, a table of common transmission media and systems, and worked threshold examples
• Annex C with a bibliography of related recommendations and earlier ETS material

For implementers, the value of these parts is practical: they support routeing design, interworking decisions, and service-quality planning rather than defining a single narrow test method.

SLOVENSKI STANDARD
01-december-2003
'LJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL,6'1±6LJQDOL]DFLMDãW±
8VPHUMDQMHNRWSRGSRUDVWRULWYDPXSRUDEQLãNHJDGHODVLVWHPD,6'1,683
UD]OLþLFD
Integrated Services Digital Network (ISDN); Signalling System No.7; Routeing in support
of ISDN User Part (ISUP) version 2 services
Ta slovenski standard je istoveten z: ETS 300 334 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 334
TELECOMMUNICATION December 1995
STANDARD
Source: ETSI TC-NA Reference: DE/NA-022108
ICS: 33.040
ISDN, ISUP, routeing, SS7
Key words:
Integrated Services Digital Network (ISDN);
Signalling System No.7;
Routeing in support of ISDN User Part (ISUP) version 2 services
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - [e-mail]
X.400: Internet:
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1995. All rights reserved.
New presentation - see History box

Page 2
ETS 300 334: December 1995
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Standards Approval Dept." at the address shown on the title page.

Page 3
ETS 300 334: December 1995
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Abbreviations.7
4 Additions and/or Clarifications to CCITT Recommendation E.172 .8
4.1 CCITT Recommendation E.172, subclause 10: Signalling capability.8
4.2 CCITT Recommendation E.172, subclause 7(k): Connection history .8
4.3 CCITT Recommendation E.172, subclause 8: Relationship between requested
services and transmission medium requirement values.8
4.4 CCITT Recommendation E.172, annex 1.8
4.5 CCITT Recommendation E.172, annex 3.8
5 Additional information on parameters used for routeing .8
5.1 Use of the transmission medium requirement parameter .8
5.1.1 Use of the TMR value "64 kbit/s unrestricted preferred".9
5.1.2 Multirate connection types.9
5.2 Relationship between requested service and TMR values.9
5.3 ISUP preference indicator values for ISDN services .10
5.3.1 Services requiring "ISUP required".11
5.3.2 Services requiring ISUP preferred.11
5.3.3 Services requiring "ISUP not required".11
5.4 Evaluation of the propagation delay counter for routeing purposes.11
5.4.1 General.11
5.4.2 Limits and actions.11
5.5 DCME links and their influence on routeing.11
6 Impact of services interworking, terminal interworking and fallback on routeing .12
7 Selection of path/traffic distribution .14
Annex A (informative): Examples of the effect of PD and DCME on routeing .16
Annex B (informative): Background information on propagation delay.17
B.1 General.17
B.2 Transmission mediums and systems taking a considerable propagation delay .17
B.3 Indication of mobile originated calls .17
B.4 Routeing for mobile originated calls .17
B.5 Threshold .17
B.6 Examples of calculation of the 70 ms threshold.18
Annex C (informative): Bibliography.19
History.20

Page 4
ETS 300 334: December 1995
Blank page
Page 5
ETS 300 334: December 1995
Foreword
This European Telecommunication Standard (ETS) has been prepared by the Network Aspects (NA)
Technical Committee of the European Telecommunications Standards Institute (ETSI), and is now
submitted for the Voting phase of the ETSI standards approval procedure.
This ETS is based upon the following source documents:
- CCITT Recommendation E.172 [1]; and
- ETS 300 100 [2].
Transposition dates
Date of adoption of this ETS: 17 November 1995
Date of latest announcement of this ETS (doa): 29 February 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 August 1996
Date of withdrawal of any conflicting National Standard (dow): 31 August 1996

Page 6
ETS 300 334: December 1995
Blank page
Page 7
ETS 300 334: December 1995
1 Scope
This European Telecommunication Standard (ETS) gives guidance on international call routeing during
the implementation of the Integrated Services Digital Network (ISDN) User Part version 2 of signalling
system No. 7 (ISDN User Part (ISUP) version 2) in the European ISDN (see ETS 300 356-1 [3]).
This ETS is applicable to the functions required at ISDN international gateways and international transit
exchanges for routeing and network planning in order to achieve practical international interconnection of
networks.
The relevant CCITT routeing Recommendation is identified and clarifications and additions to this are
provided, where necessary. In addition, CCITT Recommendations E.170 and E.171 need to be
considered.
This ETS covers services offered during the implementation of ISDN, using ISUP version 2 in the
international network. The list of services can be found in table 2 of this ETS.
2 Normative references
This ETS incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] CCITT Recommendation E.172 (1992): "ISDN Routing Plan".
[2] ETS 300 100: "Integrated Services Digital Network (ISDN); Routing in support of
ISUP version 1 services".
[3] ETS 300 356-1: "Integrated Services Digital Network (ISDN); Signalling System
No.7; ISDN User Part (ISUP) version 2 for the international interface; Part 1:
Basic services [ITU-T Recommendations Q.761 to Q.764 (1993), modified]".
3 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
CUG Closed User Group
DCME Digital Circuit Multiplication Equipment
DTX Discontinuous Transmission
GMSC Gateway Mobile Switching Centre
ISC International Switching Centre
IDN Integrated Digital Network
IPI ISUP Preference Indicator
ISDN Integrated Services Digital Network
ISUP ISDN User Part
MOC Mobile Originated Call
PD Propagation Delay
PDC Propagation Delay Counter
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
PSPDN Public Switched Packet Data Network
TMR Transmission Medium Requirement
TUP Telephone User Part
TUP+ Enhanced Telephone User Part

Page 8
ETS 300 334: December 1995
4 Additions and/or Clarifications to CCITT Recommendation E.172
4.1 CCITT Recommendation E.172, subclause 10: Signalling capability
Subclause 5.3 of this ETS contains the application of the criteria for setting the ISUP Preference Indicator
(IPI) parameter for the implementation of ISDN in Europe for ISUP version 2.
4.2 CCITT Recommendation E.172, subclause 7(k): Connection history
Subclause 5.4 of this ETS contains the application of the Propagation Delay Counter (PDC) for routeing
purposes and subclause 5.5 describes the influence of Digital Circuit Multiplication Equipment (DCME)
links on routeing in ISUP version 2.
4.3 CCITT Recommendation E.172, subclause 8: Relationship between requested services
and transmission medium requirement values
The information in CCITT Recommendation E.172 [1], subclause 8 is extended in subclauses 5.1 and 5.2
of this ETS, to cover the implementation of ISDN in Europe for ISUP version 2. The service interworking
situation from the Public Switched Telephone Network (PSTN) to the ISDN is further detailed in clause 6
of this ETS.
4.4 CCITT Recommendation E.172, annex 1
The application of the criteria defined in CCITT Recommendation E.172 [1], annex 1, to the
implementation of ISDN in Europe for ISUP version 2 is specified in subclause 5.3 of this ETS.
4.5 CCITT Recommendation E.172, annex 3
The application of parts of the criteria defined in CCITT Recommendation E.172 [1], annex 3, this annex
to the implementation of ISDN in Europe for ISUP version 2 is specified and extended in clause 6 of this
ETS.
5 Additional information on parameters used for routeing
5.1 Use of the transmission medium requirement parameter
The use of the ISUP Transmission Medium Requirement (TMR) parameter for routeing is described in
CCITT Recommendation E.172 [1], subclause 7 g). In addition to the statements made in CCITT
Recommendation E.172 [1], the following shall apply:
- for a specific service request, one TMR value shall be used in the international network and across
internetwork boundaries. The changing of TMR values shall only be allowed when fall-back occurs.
For its value, see subclause 5.2.
It is recommended that national networks use the same TMR values as the international network.
Conversion from the requested service to the TMR value can then be performed in the originating local
exchange. If not done there, then the TMR shall be available at the outgoing international gateway and
onwards. It shall then be forwarded to following exchanges, if possible, even up to the destination
exchange.
At international transit exchanges, as well as at incoming international gateway exchanges, the TMR shall
be examined for routeing purpose, irrespective of the service requested. This does not preclude that
incoming gateway exchanges may need to examine additional information available to determine national
routeing.
Page 9
ETS 300 334: December 1995
5.1.1 Use of the TMR value "64 kbit/s unrestricted preferred"
In addition to the TMR values mentioned in CCITT Recommendation E.172 [1], subclause 8, a new TMR
value has been created for the purpose of indicating when fall-back from 64 kbit/s unrestricted to speech
or 3,1 kHz audio is allowed. The value of this TMR is "64 kbit/s unrestricted preferred".
The settings and the procedure at an interworking point for this TMR value are described in subclause
7.3.35 of ETS 300 356-1 [3].
If, at an interworking point, there is no route available supporting TMR "64 kbit/s unrestricted preferred",
then the fallback procedure should be carried out at this point.
5.1.2 Multirate connection types
Multirate connections are multiple circuit switched connections (n x 64 kbit/s) with a bandwidth between
128 kbit/s and 1 920 kbit/s.
n x 64 kbit/s connections are restricted to operate within a 2 Mbit/s system. The following TMR values are
given in ETS 300 356-1 [3]:
- 2 x 64 kbit/s unrestricted (not used);
- 384 kbit/s unrestricted;
- 1 536 kbit/s unrestricted;
- 1 920 kbit/s unrestricted.
5.2 Relationship between requested service and TMR values
Table 1 gives TMR values for ISDN services to be used across international and internetwork boundaries.

Page 10
ETS 300 334: December 1995
Table 1
TMR value
Requested Service speech 3,1 kHz 64 kbit/s 64 kbit/s
audio unrestricted unrestricted
preferred
(note 3)
64 kbit/s unrestricted X
3,1 kHz audio X
Bearer speech X
service Packet mode case A:B-c X
(note 1)
Packet mode case B:B-c X
(note 1)
Packet mode case B:D-c X
(notes 1, 2)
Telephony 3,1 kHz X
Telefax Group 4 X
Teletex X
7 kHz telephony without fall-back X
Tele
service 7 kHz telephony with fall-back X
(note 3
...