SIST EN 300 141-1 V1.2.4:2005

• Abstract:

  Update references from ETS 300 102-1 and associated I-ETSs to ETS 300 403.

• Status: Published
• Publication Date: 31-Mar-2005
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2005
• Due Date: 01-Apr-2005
• Completion Date: 01-Apr-2005
• Ref Project: ETSI EN 300 141-1 V1.2.4 (1998-06) - Integrated Services Digital Network (ISDN); Call Hold (HOLD) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification

SIST EN 300 141-1 V1.2.4:2005 is the Slovenian adoption of the ETSI standard for the Integrated Services Digital Network (ISDN) Call Hold (HOLD) supplementary service. It specifies the stage 3 Digital Subscriber Signalling System No. one (DSS1) protocol: the signalling procedures, state handling and message coding needed for a user to hold and later retrieve an existing circuit-switched call.

The document is aimed at equipment and network implementations that support HOLD at the T reference point or the coincident S and T reference point, including access through a private ISDN. In practice, it tells implementers how the network and the user side exchange HOLD and RETRIEVE messages, how notifications are sent, and how conformance testing is supported by the companion parts of the standard.

What does SIST EN 300 141-1 V1.2.4:2005 specify?

SIST EN 300 141-1 V1.2.4:2005 specifies the stage 3 protocol for the HOLD supplementary service in an ISDN environment. It focuses on DSS1 signalling for public ISDN access and also covers the T reference point when the service is reached through a private ISDN.

The document is organized into clauses on scope, references, definitions, abbreviations, service description, operational requirements, coding, state definitions, procedures, interworking, timer values and SDL diagrams. It also includes two informative annexes that help readers understand signalling behaviour and what changed from the previous edition.

Annex	What it covers
Annex A	Informative signalling flows for HOLD and retrieve behaviour
Annex B	Informative changes with respect to the previous ETS 300 141-1

What are the key requirements of SIST EN 300 141-1 V1.2.4:2005?

SIST EN 300 141-1 V1.2.4:2005 defines how HOLD works, what the network must check before accepting a request, which messages and notification indicators are used, and how failed requests are rejected. For an implementer, the practical effect is that the user side, the network side and any test system can all follow the same call-hold and call-retrieve sequence.

Service behaviour and call handling

Clause 5 states that when HOLD is invoked, communication on the B-channel is interrupted, the B-channel is released, and the network reserves a B-channel for later reuse by user A. That means HOLD is not just a signalling marker - it changes the live bearer path and prepares for a later return to speech or data transfer.

Clause 9 limits when user A may request hold. At the originating side, HOLD may be requested in the Active state and, as a network option, in the Call Delivered state; at the destination side, it may be requested in the Active state. This matters because implementations have to validate the current call state before acting on a hold request.

Network checks and reservation

Clause 9.1.1 requires the network to check that the basic service is valid, that user A is subscribed to HOLD, and that the network is in an acceptable state before performing the Hold function. The normal reservation method is the implicit channel reservation function; the explicit channel reservation function is optional and depends on bilateral agreement. In practice, this defines the decision points that a network or PBX must implement before it releases and reserves channels.

Messages and coding

Clause 7 names the HOLD and RETRIEVE message family used for invocation and control: HOLD, HOLD ACKNOWLEDGE, HOLD REJECT, RETRIEVE, RETRIEVE ACKNOWLEDGE and RETRIEVE REJECT. It also assigns additional Notification indicator codepoints for remote hold and remote retrieval. This tells protocol developers exactly which DSS1 messages and notification indications the service uses.

State definitions

Clause 8 defines protocol states for the service, including HOLD Idle, HOLD Hold Requested, HOLD Call Held and HOLD Retrieve Requested on the user side, plus HOLD Idle and HOLD Call Held on the network side. These are protocol states used for the specification, not necessarily implementation states. That distinction matters in testing, because a product can comply without exposing the same internal state names.

Notifications to the remote user

Clauses 9.2 and 9.4 require the network to inform user B when a call is held or retrieved. The network sends a Notification indicator information element with the descriptions remote hold and remote retrieval, using the procedures of EN 300 196-1. In practice, this is what lets the other party know that the call has been suspended or resumed.

Error handling and interworking

Clause 9.1.2 lists the reject causes used when HOLD cannot be completed, including cases where the service is not subscribed, not implemented, the call state is invalid, or the call is not a circuit-mode call. Clause 10 adds private ISDN interworking behaviour: if HOLD or RETRIEVE messages arrive and are not implemented, the network rejects them using EN 300 403-1 error handling; if they are implemented, it rejects them with HOLD REJECT or RETRIEVE REJECT and cause #29, Facility rejected. This gives vendors a clear fallback behaviour for mixed public and private networks.

Supplementary services, timers and SDL

Clause 12 points to EN 300 195-1 for interactions with other supplementary services, so HOLD is not implemented in isolation. Clause 13 says there are no timers beyond those already defined in EN 300 196-1. Clause 14 provides SDL diagrams for the user and network processes, which are useful for design reviews, implementation logic and protocol conformance work.

What terms does SIST EN 300 141-1 V1.2.4:2005 define?

SIST EN 300 141-1 V1.2.4:2005 defines several terms that anchor the protocol description.

• basic service - a bearer service or teleservice; the standard uses this term when checking whether HOLD can apply to the call.
• Integrated Services Digital Network (ISDN) - the network environment in which this DSS1 service is specified.
• network - the DSS1 protocol entity on the network side of the user-network interface.
• service; telecommunication service - the general service concept used for HOLD and related supplementary services.
• supplementary service - a service that adds to a basic telecommunication service, such as HOLD.
• user A - the user who invokes HOLD; this is the served user.
• user B - the other party in the call; this is the non-served user.
• DSS1 - Digital Subscriber Signalling System No. one, the signalling system used by the protocol.

Who uses SIST EN 300 141-1 V1.2.4:2005?

SIST EN 300 141-1 V1.2.4:2005 is used by ISDN equipment designers, signalling protocol engineers, telecom network operators and test laboratories. It is also relevant to service providers that offer HOLD as a subscribed or generally available supplementary service.

In practice, users apply it when implementing DSS1 call control, verifying interworking at the T reference point, checking private ISDN behaviour, or building conformance tests. The foreword also notes that later parts of the series define PICS, TSS&TP and ATS/PIXIT material for user-side and network-side testing.

What changed in SIST EN 300 141-1 V1.2.4:2005 from the previous edition?

SIST EN 300 141-1 V1.2.4:2005 replaces the earlier ETS 300 141-1 and updates the references to the basic call specifications. Annex B says the changes include conversion to EN layout, replacement of references to ETS 300 102 with EN 300 403, and replacement of non-specific basic-standard references so they point to the latest versions.

Which standards are used with SIST EN 300 141-1 V1.2.4:2005?

The document cites the following references and companion parts:

Reference	What it contributes
CCITT Recommendation I.411	Reference configurations for ISDN user-network interfaces
CCITT Recommendation I.130	The three-stage method used to describe telecommunication services
CCITT Recommendation I.112	Vocabulary for ISDN terms used in the definitions
EN 300 403-1	Basic call control protocol and call-state framework
EN 300 196-1	Generic functional protocol for supplementary services, including Hold and Retrieve functions
EN 300 195-1	Interactions between supplementary services
CCITT Recommendation Z.100	SDL notation used for the dynamic description
CCITT Recommendation I.210	Principles used to describe telecommunication services

The foreword also identifies the companion parts of the EN 300 141 series: Part 2 covers the PICS proforma, Parts 3 and 5 cover TSS&TP specifications for user and network, and Parts 4 and 6 cover ATS and partial PIXIT proforma specifications for user and network.

What does the SIST EN 300 141-1 V1.2.4:2005 document contain?

SIST EN 300 141-1 V1.2.4:2005 contains the protocol specification, state model and signalling procedures for HOLD, plus the coding rules for the DSS1 messages used by the service. It also includes operational requirements, including subscription and channel-reservation behaviour.

The document uses tables for the service states, reject cause usage and notification codepoints. It also gives SDL diagrams for the user process and the network process, which are intended to support design and implementation of the protocol logic.

Annex A provides an informative example of signalling flows for a successful hold-and-retrieve sequence. Annex B summarizes the differences from the previous ETS 300 141-1, which helps readers track what was updated in this edition.

SLOVENSKI STANDARD
01-april-2005
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Integrated Services Digital Network (ISDN); Call Hold (HOLD) supplementary service;
Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol
specification
Ta slovenski standard je istoveten z: EN 300 141-1 Version 1.2.4
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.

EN 300 141-1 V1.2.4 (1998-06)
European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
Call Hold (HOLD) supplementary service;
Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification

2 EN 300 141-1 V1.2.4 (1998-06)
Reference
REN/SPS-05145-S-1 (1b090iqo.PDF)
Keywords
ISDN, HOLD, DSS1, supplementary service
ETSI
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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
3 EN 300 141-1 V1.2.4 (1998-06)
Contents
Intellectual Property Rights. 4
Foreword. 4
1 Scope . 6
2 Normative references. 6
3 Definitions. 7
4 Abbreviations.7
5 Description . 7
6 Operational requirements . 7
6.1 Provision and withdrawal.7
6.2 Requirements on the originating network side.7
6.3 Requirements on the destination network side .8
7 Coding requirements. 8
8 State definitions. 8
9 Signalling procedures at the coincident S and T reference point . 9
9.1 Holding a call - procedures at the interface of user A.9
9.1.1 Normal operation .9
9.1.2 Exceptional procedures.9
9.2 Holding a call - procedures at the interface of user B.10
9.2.1 Normal operation .10
9.2.2 Exceptional procedures.10
9.3 Retrieving a call - procedures at the interface of user A.10
9.3.1 Normal operation .10
9.3.2 Exceptional procedures.10
9.4 Retrieving a call - procedures at the interface of user B.10
9.4.1 Normal operation .10
9.4.2 Exceptional procedures.11
10 Procedures for interworking with private ISDNs . 11
10.1 User A is on a private ISDN .11
10.1.1 Normal operation .11
10.1.2 Exceptional procedures.11
10.2 User B is on a private ISDN .11
10.2.1 Normal operation .11
10.2.2 Exceptional procedures.11
11 Interactions with other networks. 11
12 Interactions with other supplementary services. 12
13 Parameter values (timers). 12
14 Dynamic description (SDL diagrams). 12
Annex A (informative): Signalling flows . 19
Annex B (informative): Changes with respect to the previous ETS 300 141-1. 20
History. 21
ETSI
4 EN 300 141-1 V1.2.4 (1998-06)
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.fr/ipr or 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 standard covering the Digital Subscriber Signalling System No. one (DSS1)
protocol specification for the Integrated Services Digital Network (ISDN) Call Hold (HOLD) supplementary service, as
described below:
Part 1: "Protocol specification";
Part 2: "Protocol Implementation Conformance Statement (PICS) proforma specification";
Part 3: "Test Suite Structure and Test Purposes (TSS&TP) specification for the user";
Part 4: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the user";
Part 5: "Test Suite Structure and Test Purposes (TSS&TP) specification for the network";
Part 6: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the network".
In accordance with CCITT Recommendation I.130, the following three level structure is used to describe the
supplementary telecommunication services as provided by European public telecommunications operators under the pan-
European Integrated Services Digital Network (ISDN):
- Stage 1: is an overall service description, from the user's stand-point;
- Stage 2: identifies the functional capabilities and information flows needed to support the service described in
stage 1; and
- Stage 3: defines the signalling system protocols and switching functions needed to implement the service described
in stage 1.
The present document details stage 3 aspects (signalling system protocols and switching functions) needed to support the
Call Hold (HOLD) supplementary service. The stage 1 and stage 2 aspects are detailed in ETS 300 139 and
ETS 300 140, respectively.
The present version updates the references to the basic call specifications.
ETSI
5 EN 300 141-1 V1.2.4 (1998-06)
National transposition dates
Date of adoption of this EN: 19 June 1998
Date of latest announcement of this EN (doa): 30 September 1998
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 March 1999
Date of withdrawal of any conflicting National Standard (dow): 31 March 1999
ETSI
6 EN 300 141-1 V1.2.4 (1998-06)
1 Scope
This first part of EN 300 141 specifies the stage three of the Call Hold supplementary (HOLD) supplementary service for
the pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications
operators at the T reference point or coincident S and T reference point (as defined in CCITT Recommendation I.411 [1])
by means of the Digital Subscriber Signalling System No. one (DSS1) protocol. Stage three identifies the protocol
procedures and switching functions needed to support a telecommunications service (see CCITT Recommendation
I.130 [2]).
In addition the present document specifies the protocol requirements at the T reference point where the service is
provided to the user via a private ISDN.
The present document does not specify the additional protocol requirements where the service is provided to the user via
a telecommunications network that is not an ISDN.
The HOLD supplementary service allows a user to interrupt communications on an existing call and then subsequently, if
desired, re-establish communications.
The HOLD supplementary service is applicable to all circuit-switched telecommunication services.
Further parts of the present document specify the method of testing required to identify conformance to the present
document.
The present document is applicable to equipment, supporting the HOLD supplementary service, to be attached at either
side of a T reference point or coincident S and T reference point when used as an access to the public ISDN.
2 Normative 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.
[1] CCITT Recommendation I.411 (1988): "ISDN user-network interfaces - Reference configurations".
[2] CCITT Recommendation I.130 (1988): "Method for the characterisation of telecommunication
services supported by an ISDN and network capabilities of an ISDN".
[3] CCITT Recommendation I.112: "Vocabulary of terms for ISDNs".
[4] EN 300 403-1: "Integrated Services Digital Network (ISDN); Digital Subscriber Signalling System
No. one (DSS1) protocol; Signalling network layer for circuit-mode basic call control; Part 1:
Protocol specification [ITU-T Recommendation Q.931 (1993), modified]".
[5] EN 300 196-1: "Integrated Services Digital Network (ISDN); Generic functional protocol for the
support of supplementary services; Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification".
[6] EN 300 195-1: "Integrated Services Digital Network (ISDN); Supplementary service interactions;
Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification".
[7] CCITT Recommendation Z.100 1988): "Functional Specification and Description Language (SDL)".
ETSI
7 EN 300 141-1 V1.2.4 (1998-06)
[8] CCITT Recommendation I.210: "Principles of telecommunication services supported by an ISDN
and the means to describe them".
3 Definitions
For the purposes of the present document, the following definitions apply:
basic service: A bearer service or teleservice. The terms bearer service and teleservice are defined in CCITT
Recommendation I.112 [3], § 2.2, definitions 202 and 203, respectively.
Integrated Services Digital Network (ISDN): See CCITT Recommendation I.112 [3], § 2.3, definition 308.
network: The DSS1 protocol entity at the network side of the user-network interface.
service; telecommunication service: See CCITT Recommendation I.112 [3], § 2.2, definition 201.
supplementary service: See CCITT Recommendation I.210 [8], § 2.4.
user A: The user which invokes the HOLD supplementary service for a given call. User A is the served user.
user B: The user engaged in the given call with user A. User B is the non-served user.
user: The DSS1 protocol entity at the user side of the user-network interface.
4 Abbreviations
For the purposes of the present document, the following abbreviations apply:
DSS1 Digital Subscriber Signalling System No. one
HOLD Call Hold
ISDN Integrated Services Digital Network
5 Description
When the HOLD supplementary service is invoked, communication on a B-channel shall be interrupted, the B-channel
shall be released, a B-channel shall be reserved by the network for subsequent reuse by user A.
6 Operational requirements
6.1 Provision and withdrawal
The HOLD supplementary service may be available by prior arrangement with the service provider or it may be generally
available. Withdrawal shall be at the request of the customer or for administrative reasons.
NOTE: As the HOLD supplementary service can often be used together with other supplementary services (e.g. ca
...