ETSI EN 301 141-1 V1.2.2 (1998-09)

SLOVENSKI STANDARD
SIST EN 301 141-1 V1.2.2:2005
01-april-2005
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Integrated Services Digital Network (ISDN); Narrowband Multi-service Delivery System
(NMDS); Part 1: NMDS interface specification
Ta slovenski standard je istoveten z: EN 301 141-1 Version 1.2.2
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
SIST EN 301 141-1 V1.2.2:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 301 141-1 V1.2.2:2005

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SIST EN 301 141-1 V1.2.2:2005
EN 301 141-1 V1.2.2 (1998-09)
European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
Narrowband Multi-service Delivery System (NMDS);
Part 1: NMDS interface specification

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SIST EN 301 141-1 V1.2.2:2005
2 EN 301 141-1 V1.2.2 (1998-09)
Reference
DEN/SPS-09054-1 (akc90ipc.PDF)
Keywords
access, basic, ISDN, NMDS, PSTN
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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 1998.
All rights reserved.
ETSI

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SIST EN 301 141-1 V1.2.2:2005
3 EN 301 141-1 V1.2.2 (1998-09)
Contents
Intellectual Property Rights.5
Foreword .5
Introduction .5
1 Scope.6
2 References.6
2.1 Normative references. 6
2.2 Informative references . 7
3 Definitions and abbreviations .7
3.1 Definitions . 7
3.2 Abbreviations. 7
4 General description .8
5 Layer 1 functions .8
5.1 Powering Aspects. 9
5.1.1 Power available from the transmission system. 9
5.1.2 NMDS behaviour under power fail conditions. 9
6 Layer 2 functions .10
6.1 Overview. 10
6.2 PSTN-GW layer 2 state machine modifications . 10
6.3 PSTN layer 2 activation. 11
7 Layer 3 messages .11
7.1 General. 12
7.2 Error handling. 12
7.3 Maintenance. 12
7.3.1 The new STATUS ENQUIRY and STATUS messages . 12
7.3.1.1 The STATUS ENQUIRY and STATUS messages for PSTN maintenance messages . 12
7.3.1.1.1 The STATUS ENQUIRY message for PSTN maintenance. 13
7.3.1.1.2 The STATUS message for PSTN maintenance. 13
7.3.1.2 The STATUS ENQUIRY and STATUS messages for ISDN maintenance messages. 14
7.3.1.2.1 The STATUS ENQUIRY message for ISDN maintenance . 14
7.3.1.2.2 The STATUS message for ISDN maintenance . 14
8 B-channel selection procedure.15
8.1 Introduction. 15
8.2 B-channel selection. 15
ETSI

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SIST EN 301 141-1 V1.2.2:2005
4 EN 301 141-1 V1.2.2 (1998-09)
Annex A (normative): B-channel selection .17
A.1 General.17
A.2 Outgoing calls (NTN to LE) .17
A.3 Call clearing .18
A.4 Incoming calls (LE to NTN) .18
A.5 PSTN-GW parked state.19
A.6 Clearing from parked state.20
Annex B (informative): Background and motivation for NMDS .21
B.1 Transparent supplementary service operation .21
B.2 Operational benefits.21
Annex C (informative): The PSTN protocol adopted for the NMDS.22
C.1 The V5 PSTN protocol .22
Annex D (informative): The relationship between a directly connected NMDS and one
supported via an access network.23
D.1 Introduction.23
Annex E (informative): The reasons for the new information element values chosen.27
E.1 General.27
E.2 Specific coding rules for information elements in the V5 specifications.27
E.3 Specific codes used for the STATUS ENQUIRY information elements for NMDS .27
E.4 Specific codes used for the STATUS information elements for NMDS.27
Annex F (informative): Permanent activation of basic access digital section.28
Annex G (informative): Remote equipment - functional requirements .29
Annex H (informative): Supplementary services useable at the NMDS .32
H.1 Applicability of PSTN supplementary services.32
H.2 Applicability of ISDN supplementary services.32
Bibliography.33
History.34
ETSI

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SIST EN 301 141-1 V1.2.2:2005
5 EN 301 141-1 V1.2.2 (1998-09)
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 SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.org/ipr).
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 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 European Standard (Telecommunications series) has been produced by ETSI Technical Committee Signalling
Protocols and Switching (SPS).
The present document is part 1 of a multi-part EN covering Narrowband Multi-service Delivery System (NMDS), as
identified below:
Part 1: "NMDS specification";
Part 2: "Protocol Implementation Conformance Statement (PICS) proforma specification".
National transposition dates
Date of adoption of this EN: 18 September 1998
Date of latest announcement of this EN (doa): 31 December 1998
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 June 1999
Date of withdrawal of any conflicting National Standard (dow): 30 June 1999
Introduction
The present document specifies the provision of Public Switched Telephone Network (PSTN) services over an existing
Integrated Services Digital Network - Basic Access (ISDN-BA) digital subscriber line (DSL). Today PSTN terminals -
normal telephones - can be connected to the S/T-interface via a Terminal Adapter (TA) with the support of services that
can be mapped at a feasible cost from ISDN (principally the basic call services).
ETSI

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SIST EN 301 141-1 V1.2.2:2005
6 EN 301 141-1 V1.2.2 (1998-09)
1 Scope
The present standard defines requirements to support the Narrowband Multi-service Delivery System (NMDS) which
provides interfaces connected via a Network Termination Node (NTN) to a Local Exchange (LE), in order to support
existing PSTN and ISDN services over an existing ISDN-Basic Access digital subscriber line (DSL).
The Narrowband Multi-Service Delivery System (NMDS) may also be connected via a V5 interface Access Network
(AN) to a Local Exchange (LE) in order to provide existing PSTN and ISDN services. This optional arrangement is
described in annex D which identifies two alternative methods to provide the same overall functionality.
The present document also contains requirements which relate to the functionality of a (new) Network Termination
Node (NTN) for supporting both Public Switched Telephone Network (PSTN) access and Integrated Services Digital
Network - Basic Access (ISDN-BA) S/T reference point interfaces over a single (digital section) transmission system as
used for existing ISDN-BA. The NTN encompasses NT2-like (noted NT2*) functionality, physical PSTN user port(s)
and PSTN protocol functionality.
An NMDS implementation may contain one ISDN-BA port and/or a limited number of PSTN ports. Typically one or
two PSTN ports would be supported.
In order to maintain an evolutionary path for PSTN services, the national V5 PSTN protocol mapping is assumed to
exist and forms an integral part of this specification.
NOTE: It is an underlying principle of the present document that, wherever practicable, steps may be taken to
minimize the cost of the NTN, subject to maintaining the required functionality.
2 References
References may be made to:
a) specific versions of publications (identified by date of publication, edition number, version number, etc.), in
which case, subsequent revisions to the referenced document do not apply; or
b) all versions up to and including the identified version (identified by "up to and including" before the version
identity); or
c) all versions subsequent to and including the identified version (identified by "onwards" following the version
identity); or
d) publications without mention of a specific version, in which case the latest version applies.
A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
2.1 Normative references
[1] ETR 080 (1996): "Transmission and Multiplexing (TM); Integrated Services Digital Network
(ISDN) basic rate access; Digital transmission system on metallic local lines".
[2] ETS 300 012-1 (1996): "Integrated Services Digital Network (ISDN); Basic User Network
Interface (UNI); Part 1: Layer 1 specification".
[3] ETS 300 324-1 (1994): "V interfaces at the digital Local Exchange (LE); V5.1 interface for the
support of Access Network (AN); Part 1: V5.1 interface specification".
[4] ETS 300 347-1 (1994): "V interfaces at the digital Local Exchange (LE); V5.2 interface for the
support of Access Network (AN); Part 1: V5.2 interface specification".
[5] ETS 300 402-2: "Integrated Services Digital Network (ISDN); Digital Subscriber Signalling
System No. one (DSS1) protocol; Data link layer; Part 2: General protocol specification
[ITU-T Recommendation Q.921 (1993), modified]".
ETSI

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SIST EN 301 141-1 V1.2.2:2005
7 EN 301 141-1 V1.2.2 (1998-09)
[6] ITU-T Recommendation I.412 (1988): "ISDN user-network interfaces - Interface structures and
access capabilities".
2.2 Informative references
[7] EN 301 141-2 (V1.2): "Narrowband Multi-service Delivery System (NMDS); Part 2: Protocol
Implementation Conformance Statement (PICS) proforma specification".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following definitions apply:
Narrowband Multi-service Delivery System: A system that provides an interface to the network directly to the LE or
via an AN to support existing PSTN and ISDN services over an ISDN-BA DSL.
Network Termination Node: The functional group on the user side of the digital section (NMDS interface noted T*
reference point) that includes functionality to support an ISDN-BA port and/or one or more PSTN ports.
Network Termination Type 2 *: The functional group within the NTN which, at the user side of the T* reference
point, performs the PSTN layer 2 and the ISDN layer 2 multiplexing and demultiplexing over the D channel, and only
interprets (and then relays) the layer 3 messages to switch the B channels to the ISDN access and the PSTN Gateways as
instructed by the signalling messages.
PSTN-Gateway: The functional group within the NTN which terminates the PSTN interface at the NTN.
T* reference point: The reference point which provides access to the NMDS, between the network termination of the
digital section (NT1) and the Network Termination Node functional group.
V1* reference point: The V1 reference point with the addition of PSTN functionality required to support the NMDS.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AN Access Network
BCC Bearer Channel Control
CPE Customer Premises Equipment
DLCI Data Link Connection Identifier
DSL Digital Subscriber Line
DTMF Dual Tone Multi-Frequency
ISDN Integrated Services Digital Network
ISDN-BA Integrated Services Digital Network - Basic Access
LE Local Exchange
NMDS Narrowband Multi-service Delivery System
NT Network Termination
NT1 NT type 1 (see ETR 080 [1])
NT2* Network Termination Type 2* (see the definition in subclause 3.1 above)
NTN Network Termination Node
NWK Network Layer
PSTN Public Switched Telephone Network
PSTN-GW PSTN Gateway
SAPI Service Access Point Identifier
TA Terminal Adapter
TE Terminal Equipment
TEI Terminal Endpoint Identifier
ETSI

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SIST EN 301 141-1 V1.2.2:2005
8 EN 301 141-1 V1.2.2 (1998-09)
UNI User Network Interface
4 General description
The purpose of the NMDS is to support both ISDN-BA and one or more PSTN user ports in the same manner such that
they appear to the user as if they were directly connected to the LE. The support of ISDN-BA user ports utilizes the
same type of functions as used by an NT1 defined in ETR 080 [1], whilst PSTN user ports are supported using the same
PSTN protocol as defined in the V5.1 interface standard ETS 300 324-1 [3] with some modifications.
The LE is service responsible for and controls the tones (voice messages etc.) sent and received over the NMDS. See
figure 1 for the functional architecture of NMDS.
UNI
LE
NTN national
PSTN
protocol
Call
PSTN
ISDN-BA DSL
User Port
Control
ISDN
layer 2
ISDN
mngmnt
User Port
Figure 1: General NMDS functional diagram
The Narrowband Multi-service Delivery System (NMDS) is defined at the T* reference point and the complementary
V1* reference point as shown in figure 2.
On any NMDS, the LE may support up to 10 PSTN (analogue) lines and the NTN may provide up to 10 PSTN
(analogue) access ports. The provision of PSTN and ISDN access ports in the LE requires a bilateral agreement between
the user and the service provider at subscription time.
5 Layer 1 functions
In order to permit transparent operation via an AN, there shall be no changes to the ISDN-BA digital section layer 1
protocols.
Layer 1 at the ISDN-BA UNI shall be in accordance with ETS 300 012-1 [2].
The NTN shall permit layer 1 activation from the ISDN UNI and layer 1 activation/deactivation from the network. In
order to keep the NTN simple, the PSTN gateway shall not require "user side" activation procedures and the network
shall maintain the digital section in a permanently activated state whenever the PSTN protocols are to be supported.
The NTN shall also allow the digital section to be activated regardless of the electrical conditions prevailing at the ISDN
UNI and PSTN port.
To prevent the possibility of the exchange/multiplexer deactivating the digital section as part of the recovery actions
resulting from an ISDN UNI error, the NTN shall always present a UNI "no error" indication to the network.
The permanent activation of the digital section may interfere with certain maintenance operations normally provided
over the embedded operations channel. To overcome any difficulties, the exchange shall be able to detect the activation
state of the ISDN UNI which would have prevailed if the PSTN ports had not been present, using a message-based
maintenance mechanism at layer 3. The ISDN UNI status information element is used for this purpose and is described
elsewhere in the present document.
The NTN shall support full ISDN layer 1 diagnostic loop capability.
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SIST EN 301 141-1 V1.2.2:2005
9 EN 301 141-1 V1.2.2 (1998-09)
The general access structure is described in ITU-T Recommendation I.412 [6]. The access structure for ISDN-BA in
ITU-T Recommendation I.412 [6] is valid also for the PSTN application. The layer 1 transporting the full NMDS
functionality from the NTN to the LE shall be an ISDN-BA layer 1.
C ustom er eq uipm ent A ccess connectio n elem ent
Rec. M .3603[8]
Z
ISD N basic access LE o r A N
NTN
transm ission syste m
PSTN-G W
T*
Rec. M .3602[7]
V *
1
S/T
2B+ D (2B 1Q /4B3T)
LT ET
NT2* NT1
ISDN basic access digital section
ETS 300 297
E T S 300 012
NOTE: The functionality and layout shown in figure 2 can only be one particular example and is not
representative of all architectures where NMDS can be applied.
In actual implementations the NT1 functional group is likely to be physically integrated in an equipment
realizing the NTN functionality.
Figure 2: An example of an NMDS scenario for NMDS
5.1 Powering Aspects
5.1.1 Power available from the transmission system
The power available for NMDS support is the actual power budget provided by the existing ISDN-BA digital section.
Additional power is expected to be provided locally to the NTN. What may happen under local power fail conditions
with respect to NTN user ports is described below. Hence there are no deviations from the requirements specified in the
ISDN-BA standards in order to support NMDS.
5.1.2 NMDS behaviour under power fail conditions
The ISDN-BA standards mandate that a designated instrument may be made available on an S/T Interface. If this
designated instrument is available, then it shall be capable of (at least) making emergency telephone calls.
For the PSTN, the situation is not mandated on a European wide basis and depends upon nationally agreed regulations
which are outside the scope of the present document.
The NMDS may be comprised of one or more PSTN ports, potentially as well as an ISDN-BA port. Hence it is not
possible to define in a standard mandatory behaviour under power-fail conditions. What is more relevant is that
manufacturers are able to adequately define their system's behaviour under power failure conditions. For this reason, a
clause has been inserted into the Protocol Implementation Conformance Statement (PICS) document, EN 301 141-2 [7],
where such behaviour may be explained.
ETSI

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SIST EN 301 141-1 V1.2.2:2005
10 EN 301 141-1 V1.2.2 (1998-09)
6 Layer 2 functions
6.1 Overview
The layer 2 used within the NMDS system, used for both PSTN and ISDN-BA services, shall be in accordance with
ETS 300 402-2 [5] but with the following restrictions.
The LE layer 2 state machine shall be as per ETS 300 402-2 [5].
The PSTN gateway layer 2 state machine shall be as defined in subclause 6.2 of the present document, providing a
restricted functionality version of the state machine in ETS 300 402-2 [5].
The PSTN gateway shall use a single permanently activated data link with a fixed Data Link Connection Identifier
(DLCI) for all communication with the network. The DLCI shall consist of a PSTN Terminal Endpoint Identifier (TEI)
allocated from the automatic TEI values (i.e. 64-126) and Service Access Point Identifier (SAPI) set equal to 0. TEI
values 117 to 126 shall be reserved for PSTN use when NMDS is implemented on an access.
The first PSTN gateway to be fitted shall use TEI 126 and be identified as Line 1. TEI values 117 to 125 are reserved
for further PSTN gateways, lines 2 to 10, as shown in the table 1.
Table 1: Allocation of TEI to PSTN ports
TEI value Line number
126 1
125 2
124 3
123 4
122 5
121 6
120 7
119 8
118 9
117 10
The PSTN gateway shall not support the broadcast data link, or TEI management procedures, and shall not initiate
layer 2 establishment, i.e. the DL_ESTABLISH_REQUEST primitive in the TEI assigned state shall not be supported.
On the ISDN port, point-to-point (i.e. TEI 0) or point-to-multipoint procedures may be supported using the full ISDN
TEI assignment procedures as currently defined. These includes TEI assignment and removal procedures. However,
some previously available values are now reserved (see table 1).
It is expected that some implementations may provide additional PSTN-GWs either as separate equipment connected to
the S/T Interface or as further integrated entities. In each case the TEI allocations shall comply with those shown in
table 1. The TEI associated with each external PSTN-GW shall be preprovisioned.
6.2 PSTN-GW layer 2 state machine modifications
The modifications required to the BA layer 2 state machine for the PSTN-GW are specified below as a list of
differences to the state machine contained in annex D of ETS 300 402-2 [5].
Delete states 1, 2, 3, 5.0, 5.2 and 6.
Delete the following input events:
- DL-ESTABLISH-REQUEST;
- DL-RELEASE-REQUEST;
- DL-UNIT DATA-REQUEST;
- UI FRAME IN QUEUE;
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SIST EN 301 141-1 V1.2.2:2005
11 EN 301 141-1 V1.2.2 (1998-09)
- MDL-ASSIGN-REQUEST;
- MDL-REMOVE-REQUEST;
- MDL-ERROR-RESPONSE;
- T203 TIME-OUT.
Renumber state 4, and all references to it, to state 9; rename the state to "LINK NOT ESTABLISHED".
Delete all instances of the following output events replacing the event with "-" if it was the only action associated with
the input event/state combination under consideration:
- DISC UI QUEUE;
- START T203;
- STOP T203;
- RESTART T203;
- MDL-ERR-IND(all variants);
- DL-UNIT-DATA-IND.
Replace all instances of "DISC I and UI QUEUES" with "DISC I QUEUE".
For input event "T200 TIME-OUT" in states 7.0 through to state 7.3 delete the "either" option.
For input event "T200 TIME-OUT; RC Replace all instances of DL-EST-IND and DL-REL-IND with MDL-EST-IND and MDL-REL-IND respectively.
Replace the action for input event "DM F=0 able to enter state 7.0" in state 9 with "-".
6.3 PSTN layer 2 activation
After installing the NTN, the PSTN-GW part of the NTN shall wait for activation from the network. As soon as layer 1
is activated, the LE shall be in a position to attempt layer 2 establishment of the PSTN-GW as and when required (as
immediate service provision may not be required).
Loss of power and resumption of power on the DSL shall force a reset of the PSTN-GW functionality to the idle
condition.
7 Layer 3 messages
The PSTN network layer (NWK) protocol shall be as defined in ETS 300 324-1 [3], clause 13. The national PSTN
mappings are beyond the scope of the present document.
The normal path establishment procedures of ETS 300 324-1 [3] shall be used.
However, the PSTN Port blocking and the PSTN Restart procedures defined in ETS 300 324-1 [3] do not apply to the
NMDS. Hence the following events described in ETS 300 324-1 [3] PSTN functional state machines (clause 13) are not
applicable: MDU-CRTL (port blocked), MDU-CTRL (port unblocked), MDU-CTL (restart request) MDU-CTRL
(restart complete). It results that the states AN0, AN6, LE0 and LE6 defined in ETS 300 324-1 [3] (subclauses 13.2.1.1
and 13.2.1.2) for the V5.1 interface are not used by the NMDS state machine.
The present document provides additions to the message formats and procedures to those found in ETS 300 324-1 [3].
The protocol discriminator value for the additional messages defined in the present document shall be the same as for
ETS 300 324-1 [3], i.e. 48H.
ETSI

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SIST EN 301 141-1 V1.2.2:2005
12 EN 301 141-1 V1.2.2 (1998-09)
7.1 General
The NTN shall support the national PSTN requirements for all applicable signals. All tones and announcements
generated by the network shall be passed as inband signalling transparently over the B-channel to the customer. In the
event of no B-channel being available then the proceed indication shall not be given to the customer until a channel
becomes available i.e. the proceed indication shall not be generated by the PSTN-GW.
DTMF dialled digits shall be passed transparently over the B-channel to the network.
7.2 Error handling
The LE shall support the full error handling procedures defined in ETS 300 324-1 [3] clause 13, relating to the V5.1
PSTN protoco
...