SIST ETS 300 392-10-24 E2:2003

• Abstract:

  Analysis of predicted needs for digital trunked systems in Europe; definition of services to be provided; analysis of spectrum req ments; characteristics of relevant interfaces Contains: TETRA 03.60 to 03.85

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.10 - Terrestrial Trunked Radio (TETRA)
• 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
• Mandate: T-172-1A
• Ref Project: ETSI ETS 300 392-10-24 ed.2 (2000-04) - Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 10: Supplementary services stage 1; Sub-part 24: Call Retention (CRT)

Overview

SIST ETS 300 392-10-24 E2:2003 defines the Call Retention (CRT) supplementary service for Terrestrial Trunked Radio (TETRA) Voice plus Data (V+D) systems in Europe. Developed by the Slovenski inštitut za standardizacijo (SIST) and aligned with ETSI standards, this document outlines how the CRT service lets TETRA users safeguard ongoing calls and data sessions from being pre-empted by lower-priority communications. The specification describes the “stage 1” user perspective, focusing on expected behaviors and service usability rather than implementation mechanics.

This standard supports the evolving requirements of digital trunked radio networks, addressing both individual and group calls for public safety, transportation, utilities, and other mission-critical sectors relying on resilient radio communications.

Key Topics

• Call Retention (CRT): A supplementary service that protects active calls in TETRA networks from unwanted pre-emption, using a Call Retention Value (CRV) to prioritize which calls remain connected when resources are constrained.
• Call Pre-emption Protection: CRT introduces different CRV levels, allowing flexible assignment of protection priorities on a per-subscriber or per-group basis.
• User Control and Network Assignment:
  • CRT can be invoked by both calling and called parties.
  • The highest CRV requested governs call protection.
  • Default protection levels are assigned if not explicitly set.
• Service Applicability: CRT applies to all circuit mode bearer and teleservices as specified in the core TETRA air interface standards. TETRA Short Data Service (SDS) is excluded.
• Interaction with Other Services: CRT is designed to work independently or in sequence with other TETRA supplementary services, such as call forwarding, call hold, and priority calls, ensuring seamless operation across complex communication scenarios.
• Configuration and Operation: CRT can be made available to all users by default or provided based on subscription or pre-arrangement as determined by the network operator.

Applications

Call Retention (CRT) is critical for:

• Public Safety and Emergency Services: Ensuring high-priority or life-saving communications are not disrupted during major incidents.
• Critical Infrastructure and Utilities: Maintaining essential communications for power, water, and transport operators where lost connectivity can impact public service delivery.
• Group Coordination: Enabling robust group call scenarios where the controlling SwMI (Switching and Management Infrastructure) equitably assigns call retention levels to all group members, supporting operational integrity during resource contention.
• Inter-network Interworking: Facilitating cooperation between TETRA networks and compatible private ISDN infrastructures to maintain retained calls across interconnected networks.
• Customizable User Privileges: Allowing organizations to assign different levels of call protection based on operational roles, such as dispatchers, supervisors, or field units.

Related Standards

• ETS 300 392-2: Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Air Interface (AI) specification.
• ECMA-263: Private Integrated Services Network (PISN); Call Priority Interruption Protection Supplementary Services.
• ITU-T Recommendation I.210: Defines principles for telecommunication services supported by ISDN.
• Other TETRA Supplementary Service Standards: Covering access priority, call completion, forwarding, and group management to create a comprehensive suite for trunked digital radio environments.

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By implementing SIST ETS 300 392-10-24 E2:2003, organizations benefit from standardized, reliable CRT capabilities within modern TETRA digital trunked radio systems, improving operational security and ensuring critical communications are maintained even under dynamic network loads.

SLOVENSKI STANDARD
01-december-2003
Prizemni snopovni radio (TETRA) – Govor in podatki (V+D) – 10. del: Dopolnilne
storitve stopnje 1 – 24. poglavje: Ohranitev klica (CRT)
Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 10: Supplementary
services stage 1; Sub-part 24: Call Retention (CRT)
Ta slovenski standard je istoveten z: ETS 300 392-10-24 Edition 2
ICS:
33.070.10 Prizemni snopovni radio Terrestrial Trunked Radio
(TETRA) (TETRA)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 392-10-24
TELECOMMUNICATION April 2000
STANDARD Second Edition
Source: TETRA Reference: RE/TETRA-03001-10-24
ICS: 33.020
Key words: Data, radio, retention, speech, stage 1, supplementary service, TETRA, V+D
Terrestrial Trunked Radio (TETRA);
VoiceplusData(V+D);
Part 10: Supplementary services stage 1;
Sub-part 24: Call Retention (CRT)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Internet: [e-mail] - http://www.etsi.org
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 2000. All rights reserved.

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ETS 300 392-10-24: April 2000
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 Standards Making Support Dept." at the address shown on the title page.

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ETS 300 392-10-24: April 2000
Contents
Foreword.5
1 Scope .7
2 Normative references.7
3 Definitions, symbols and abbreviations .7
3.1 Definitions .7
3.2 Symbols .8
3.3 Abbreviations .8
3.3.1 General abbreviations .8
3.3.2 Supplementary service abbreviations.9
4 SS-CRT stage 1 specification .9
4.1 Description .9
4.1.1 General description .9
4.1.2 Qualifications on applicability to telecommunication services .10
4.2 Procedure .10
4.2.1 Provision/withdrawal.10
4.2.2 Normal procedures.10
4.2.2.1 Activation/deactivation/registration/interrogation .10
4.2.2.1.1 Void.10
4.2.2.1.2 Definition .10
4.2.2.1.3 Registration.10
4.2.2.1.4 Interrogation.10
4.2.2.1.5 Cancellation .11
4.2.2.2 Invocation and operation.11
4.2.2.2.1 Invocation by a calling user.11
4.2.2.2.2 Invocation by a called user.12
4.2.3 Exceptional procedures.12
4.2.3.1 Activation/deactivation/registration/interrogation .12
4.2.3.1.1 Void.12
4.2.3.1.2 Interrogation.12
4.2.3.2 Invocation and operation.12
4.3 Interaction with other supplementary services and ANFs.12
4.3.1 Access Priority (SS-AP).13
4.3.2 Advice of Charge (SS-AOC).13
4.3.3 Ambience Listening (SS-AL) .13
4.3.4 Area Selection (SS-AS).13
4.3.5 Barring of Incoming Calls (SS-BIC).13
4.3.6 Barring of Outgoing Calls (SS-BOC) .13
4.3.7 Call Authorized by Dispatcher (SS-CAD) .13
4.3.8 Call Completion on No Reply (SS-CCNR).13
4.3.9 Call Completion to Busy Subscriber (SS-CCBS).13
4.3.10 Call Forwarding Busy (SS-CFB).13
4.3.11 Call Forwarding No Reply (SS-CFNRy).13
4.3.12 Call Forwarding Not Reachable (SS-CFNRc) .13
4.3.13 Call Forwarding Unconditional (SS-CFU).13
4.3.14 Call Hold (SS-HOLD).14
4.3.15 Call Report (SS-CR).14
4.3.16 Call Waiting (SS-CW).14
4.3.17 Calling Line Identification Presentation (SS-CLIP).14
4.3.18 Calling/Connected Line identification Restriction (SS-CLIR).14
4.3.19 Connected Line identification Presentation (SS-COLP).14
4.3.20 Discreet Listening (SS-DL).14
4.3.21 Dynamic Group Number Assignment (SS-DGNA).14
4.3.22 Include Call (SS-IC).14

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ETS 300 392-10-24: April 2000
4.3.23 Late Entry (SS-LE). 14
4.3.24 List Search Call (SS-LSC) . 14
4.3.25 Pre-emptive Priority Call (SS-PPC) . 14
4.3.26 Priority Call (SS-PC) . 15
4.3.27 Short Number Addressing (SS-SNA). 15
4.3.28 Talking Party Identification (SS-TPI). 15
4.3.29 Transfer of Control (SS-TC) . 15
4.3.30 Transit Counter (ANF-TC) . 15
4.3.31 ANF-ISI-IC . 15
4.3.32 ANF-ISI-GC. 15
4.3.33 ANF-ISI-MM. 15
4.4 Inter-working considerations . 15
4.5 Overall SDL . 15
Annex A (informative): Bibliography . 18
History. 19

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ETS 300 392-10-24: April 2000
Foreword
This European Telecommunication Standard (ETS) has been produced by the Terrestrial Trunked Radio
(TETRA) Project of the European Telecommunications Standards Institute (ETSI).
This ETS is a multi-part standard and will consist of the following parts:
Part 1: "General network design";
Part 2: "Air Interface (AI)";
Part 3: "Interworking at the Inter-System Interface (ISI)";
Part 4: "Gateways basic operation”;
Part 5: “Peripheral Equipment Interface (PEI)";
Part 6: "Line connected Station (LS)";
Part 7: "Security";
Part 9: "General requirements for supplementary services";
Part 10: "Supplementary services stage 1";
Part 11: "Supplementary services stage 2";
Part 12: "Supplementary services stage 3";
Part 13: "SDL model of the Air Interface (AI)";
Part 14: "Protocol Implementation Conformance Statement (PICS) proforma specification”.
Transposition dates
Date of adoption of this ETS: 14 April 2000
Date of latest announcement of this ETS (doa): 31 July 2000
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 January 2001
Date of withdrawal of any conflicting National Standard (dow): 31 January 2001

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ETS 300 392-10-24: April 2000
1 Scope
This ETS specifies the supplementary service Call Retention SS-CRT which is applicable to various basic
services supported by TETRA SwMIs. Basic services are specified in ETS 300 392-2 [4].
SS-CRT is a supplementary service which applies either during call establishment or once call is
established to protect a call from pre-emption by another call of lower priority.
Supplementary service specifications are produced in three stages, according to the method described in
ITU-T Recommendation I.210 [2]. The present document contains the stage 1 specifications of SS-CRT.
The stage 1 descriptions specify the supplementary services as seen by users of networks.
This ETS is applicable to circuit mode TETRA V+D tele-services and bearer services. This ETS is not
applicable to TETRA Short Data Service (SDS).
Man Machine Interfaces and charging principles are outside the scope of this ETS.
This second edition of this ETS is based on the latest edition of ECMA-263 [1]. The first edition of this ETS
was drafted at a time where no published text of ECMA-263 [1] existed. Additions to ECMA-263 [1] have
been made to take into account particular TETRA specifics such as group calls and to include user
requirements and situations not addressed in ECMA-263 [1].
2 Normative references
This ETS incorporates by dated and 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] ECMA-263 (1997): "Private Integrated Services Network (PISN) -
Specification, Functional Model and Information Flows -
Call Priority Interruption and Call Priority Interruption Protection Supplementary
Services (CPI(P)SD)".
[2] ITU-T Recommendation I.210 (1993): "Principles of telecommunication services
supported by an ISDN and the means to describe them".
[3] ITU-T Recommendation Z.100 (1993): "CCITT Specification and description
language (SDL)".
[4] ETSI ETS 300 392-2 (1995): "Terrestrial Trunked Radio (TETRA); Voice plus
Data (V+D); Part 2: Air Interface (AI)".
[5] ETSI ETS 300 392-10-24 (1996): "Terrestrial Trunked Radio (TETRA); Voice
plus Data (V+D); Part 10: Supplementary services stage 1; Part 10-24: Call
retention".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
Call Priority Interruption Capability Level (CPICL): parameter indicating the priority of a call
(ECMA-263); will be used in case of interworking
Call Priority Interruption Protection Level (CPIPL): parameter indicating a level of protection of a call
against interruption from other calls (ECMA-263); will be used in case of interworking

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ETS 300 392-10-24: April 2000
Call Retention Value (CRV): value which defines the relative level of protection of established calls
against pre-emption
established call: active call that is selected for interruption
impending priority interruption state: condition of an established call and a priority call after provision of
an Impending priority interruption warning notification and before the release of the established call
impending priority interruption warning notification: notification provided before the release of the
established call
non-priority call: call that has not been assigned any level of priority
NOTE 1: A non-priority call may be a protected call.
non-protected call: call that has not been assigned any level of protection
NOTE 2: A non-protected call may be a priority call.
priority call: call that has been assigned some level of priority (by a PC or PPC value)
NOTE 3: A priority call may also be a protected call.
protected call: call that has been assigned some level of protection (by a Call Retention Value)
NOTE 4: A protected call may also be a priority call.
served user: user who requests SS-CRT
Switching and Management Infrastructure (SwMI): all of the TETRA equipment for a Voice plus Data
(V+D) network except for subscriber terminals. The SwMI enables subscriber terminals to communicate
with each other via the SwMI
time to priority interruption: duration of the impending priority interruption state
unprotected call: call which has not been assigned a CRV value or has a CRV value equal to zero
3.2 Symbols
For the purposes of this ETS, there are no additional symbols excepted the symbols used in the SDL
representation (ITU-T Recommendation Z.100 [3]).
3.3 Abbreviations
3.3.1 General abbreviations
For the purposes of this ETS, the following general abbreviations apply:
GTSI Group TETRA Subscriber Identity
ISDN Integrated Services Digital Network
ISI Inter System Interface
ITSI Individual TETRA Subscriber Identity
SDL (Functional) Specification and Description Language
SS Supplementary Service
NOTE: The abbreviation SS is only used when referring to a specific supplementary service.
SwMI Switching and Management Infrastructure
TETRA Terrestrial Trunked RAdio

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ETS 300 392-10-24: April 2000
3.3.2 Supplementary service abbreviations
For the purposes of this ETS, the following Supplementary Service abbreviations apply:
AL Ambience Listening
AoC Advice of Charge
AP Access Priority
AS Area Selection
BIC Barring of Incoming Calls
BOC Barring of Outgoing Calls
CAD Call Authorized by Dispatcher
CCBS Call Completion to Busy Subscriber
CCNR Call Completion on No Reply
CFB Call Forwarding on Busy
CFNRy Call Forwarding on No Reply
CFNRc Call Forwarding on Not Reachable
CFU Call Forwarding Unconditional
CLIP Calling Line Identification Presentation
CLIR Calling/Connected Line Identification Restriction
COLP Connected Line Identification Presentation
CR Call Report
CRT Call Retention
CRV Call Retention Value
CW Call Waiting
DGNA Dynamic Group Number Assignment
DL Discreet Listening
HOLD Call Hold
IC Include Call
LE Late Entry
LSC List Search Call
PC Priority Call
PPC Pre-emptive Priority Call
SNA Short Number Addressing
TC Transfer of Control
TPI Talking Party Identification
4 SS-CRT stage 1 specification
4.1 Description
4.1.1 General description
Call Retention (SS-CRT) is a supplementary service that allows the protection of calls against
pre-emption. SS-CRT enables the user to define a relative level of call protection, once established,
against the probability of having the network connection resources pre-empted.
Every call in a Switching and Management Infrastructure (SwMI) shall be assigned a Call Retention Value
(CRV), and, i
...