ISO/IEC 15992:2003

INTERNATIONAL ISO/IEC
STANDARD 15992
Second edition
2003-04-01
Information technology —
Telecommunications and information
exchange between systems — Private
Integrated Services Network —
Inter-exchange signalling protocol —
Call Priority Interruption and Call Priority
Interruption Protection supplementary
services
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Réseau privé à intégration de
services — Protocole de signalisation d'échange — Services
supplémentaires d'interruption de priorité d'appel et de protection
d'interruption de priorité d'appel

Reference number
©
ISO/IEC 2003
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©  ISO/IEC 2003
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ii © ISO/IEC 2003 — All rights reserved

Contents
Foreword v
Introduction vi
1 Scope 1
2 Conformance 1
3 Normative references 1
4 Terms and definitions            2
4.1 External definitions 2
4.2 Called user 3
4.3 Calling user 3
4.4 Call interruption 3
4.5 Call Priority Interruption Capability Level (CPICL) 3
4.6 Call Priority Interruption Protection Level (CPIPL) 3
4.7 Call protection 3
4.8 Established call 3
4.9 Established call user 3
4.10 Established call user's PINX 3
Forced release
4.11 3
4.12 Inter-PINX link 3
4.13 Interrupting PINX 3
4.14 Non-priority call 3
4.15 Priority call 3
4.16 Protected call 3
5 List of acronyms 3
6 Signalling protocol for the support of SS-CPI(P) 4
SS-CPI(P) description
6.1 4
6.2 SS-CPI(P) operational requirements 4
6.2.1 Requirements on the Originating PINX 4
6.2.2 Requirements on the Terminating PINX 4
6.2.3 Requirements on a Transit PINX 4
6.2.4 Requirements on the Interrupting PINX 4
6.2.5 Requirements on the Established call user's PINX 4
6.3 SS-CPI(P) coding requirements 5
6.3.1 Operations 5
6.3.2 Notifications 6
6.3.3 Information elements 6
6.3.4 Messages 7
6.4 SS-CPI state definitions 7
6.4.1 States at the Originating PINX 7
6.4.2 States at the Transit PINX 7
6.4.3 States at the Interrupting PINX 7
6.5 SS-CPIP state definitions 7
States at the Originating PINX
6.5.1 7
6.5.2 States at the Transit PINX 7
6.5.3 States at the Terminating PINX 7
© ISO/IEC 2003 – All rights reserved iii

6.6 SS-CPI signalling procedures for activation, deactivation and registration 8
6.7 SS-CPIP signalling procedures for activation, deactivation and registration 8
6.8 SS-CPI signalling procedures for invocation and operation 8
6.8.1 Actions at the Originating PINX 8
6.8.2 Actions at a Transit PINX 8
6.8.3 Actions at the Interrupting PINX 9
6.8.4 Actions at the Terminating PINX 10
6.8.5 Actions at the Established call user's PINX 10
6.9 SS-CPIP signalling procedures for invocation and operation 10
6.9.1 Actions at the Originating PINX 10
6.9.2 Actions at a Transit PINX 10
6.9.3 Actions at the Terminating PINX 11
SS-CPI impact of interworking with public ISDNs
6.10 11
6.11 SS-CPIP impact of interworking with public ISDNs 11
6.12 SS-CPI impact of interworking with non-ISDNs 11
6.13 SS-CPIP impact of interworking with non-ISDNs 12
6.14 Protocol interactions between SS-CPI(P) and other supplementary services and ANFs 12
6.14.1 Interaction with Calling Name Identification Presentation (SS-CNIP) 12
6.14.2 Interaction with Connected Name Identification Presentation (SS-CONP) 12
6.14.3 Interaction with Completion of Call to Busy Subscriber (SS-CCBS) 12
Interaction with Completion of Call on No Reply (SS-CCNR)
6.14.4 12
6.14.5 Interaction with Call Transfer (SS-CT) 12
6.14.6 Interaction with Call Forwarding Unconditional (SS-CFU) 12
6.14.7 Interaction with Call Forwarding Busy (SS-CFB) 13
6.14.8 Interaction with Call Forwarding No Reply (SS-CFNR) 13
6.14.9 Interaction with Call Deflection (SS-CD) 13
6.14.10 Interaction with Path Replacement (ANF-PR) 13
6.14.11 Interaction with Call Offer (SS-CO) 13
6.14.12 Interaction with Call Intrusion (SS-CI) 13
6.14.13 Interaction with Do not Disturb (SS-DND) 13
6.14.14 Interaction with Do not Disturb Override (SS-DNDO) 13
6.14.15 Interaction with Advice of Charge (SS-AOC) 13
6.14.16 Interaction with Recall (SS-RE) 13
6.14.17 Interaction with Call Interception (ANF-CINT) 13
6.14.18 Interaction with Transit Counter (ANF-TC) 13
6.14.19 Interaction with Wireless Terminal Location Registration (SS-WTLR) 14
6.14.20 Interaction with Wireless Terminal Incoming Call (ANF-WTMI) 14
Interaction with Wireless Terminal Outgoing Call (ANF-WTMO)
6.14.21 14
6.14.22 Interaction with Wireless Terminal Authentication of a WTM user (SS-WTAT) 14
6.14.23 Interaction with Wireless Terminal Authentication of a PISN (SS-WTAN) 14
6.14.24 Interaction with Message Waiting Indication (SS-MWI) 14
6.14.25 Interaction with Common Information (ANF-CMN) 14
6.15 SS-CPI parameter values (timers) 14
6.15.1 Timer T1 14
Annexes
A - Protocol Implementation Conformance Statement (PICS) proforma 15
B - Examples of message sequences 23
C - Specification and Description Language (SDL) representation of procedures 28
D - ASN.1 definitions according to ITU-T Recs. X.208 / X.209 36
iv © ISO/IEC 2003 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In
the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by
the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires
approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and
IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 15992 was prepared by ECMA (as ECMA-264) and was adopted, under a special “fast-track procedure”, by Joint
Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by national bodies of ISO and IEC.
This second edition cancels and replaces the first edition (ISO/IEC 15992:1998), which has been technically revised.

© ISO/IEC 2003 – All rights reserved v

Introduction
This International Standard is one of a series of Standards defining services and signalling protocols applicable to Private
Integrated Services Networks (PISNs). The series uses ISDN concepts as developed by ITU-T and conforms to the framework
of International Standards for Open Systems Interconnection as defined by ISO/IEC.
This International Standard specifies the signalling protocol for use at the Q reference point in support of the Call Priority
Interruption (CPI) and Call Priority Interruption Protection (CPIP) supplementary services. The protocol defined in this
International Standard forms part of the PSS1 protocol (informally known as QSIG).
This International Standard is based upon the practical experience of ECMA member companies and the results of their active
and continuous participation in the work of ISO/IEC JTC 1, ITU-T, ETSI and other international and national standardization
bodies. It represents a pragmatic and widely based consensus.
vi © ISO/IEC 2003 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 15992:2003(E)

Information technology — Telecommunications and information
exchange between systems — Private Integrated Services Network —
Inter-exchange signalling protocol — Call Priority Interruption and Call
Priority Interruption Protection supplementary services
1Scope
This International Standard specifies the signalling protocol for the support of the Call Priority Interruption (SS-CPI) and Call
Priority Interruption Protection (SS-CPIP) supplementary services at the Q reference point between Private Integrated services
Network eXchanges (PINXs) connected together within a Private Integrated Services Network (PISN).
NOTE 1 - This edition of this International Standard does not apply to calls using the circuit-mode multiple rate bearer service.
SS-CPI allows a call request for a priority call to proceed successfully in the case that there is no user information channel
available. This is accomplished by force releasing an established call of lower priority.
SS-CPIP allows for the protection of calls against interruption from priority calls.
The Q reference point is defined in ISO/IEC 11579-1.
Service specifications are produced in three stages and according to the method specified in ETS 300 387. This International
Standard contains the stage 3 specification for the Q reference point and satisfies the requirements identified by the stage 1 and
stage 2 specifications in ISO/IEC 15991.
The signalling protocol for SS-CPI(P) operates on top of the signalling protocol for basic circuit switched call control, as
specified in ISO/IEC 11572, and uses certain aspects of the generic procedures for the control of supplementary services
specified in ISO/IEC 11582.
This International Standard also specifies additional signalling protocol requirements for the support of interactions at the Q
reference point between SS-CPI(P) and other supplementary services and ANFs.
NOTE 2 - Additional interactions that have no impact on the signalling protocol at the Q reference point can be found in the relevant stage 1
specifications.
This International Standard is applicable to PINXs that can interconnect to form a PISN.
2 Conformance
In order to conform to this International Standard, a PINX shall satisfy the requirements identified in the Protocol
Implementation Conformance Statement (PICS) proforma in annex A.
Conformance to this International Standard includes conforming to those clauses that specify protocol interactions between
SS-CPI(P) and other supplementary services and ANFs for which signalling protocols at the Q reference point are supported in
accordance with the stage 3 standards concerned.
3 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the
edition cited applies. For undated references, the latest edition of the referenced document (including any amendments)
applies.
ISO/IEC 11572:2000, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Circuit mode bearer services - Inter-exchange signalling procedures and protocol
ISO/IEC 11574:2000, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Circuit-mode 64 kbit/s bearer services - Service description, functional capabilities and
information flows
ISO/IEC 11579-1:1994, Information technology - Telecommunications and information exchange between systems - Private
integrated services network - Part 1: Reference configuration for PISN Exchanges (PINX)
© ISO/IEC 2003 – All rights reserved 1

ISO/IEC 11582:2002, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Generic functional protocol for the support of supplementary services - Inter-exchange
signalling procedures and protocol
ISO/IEC 13869:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Call Transfer supplementary service
ISO/IEC 13873:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Call Diversion supplementary services
ISO/IEC 13874:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Path Replacement additional network feature
ISO/IEC 15054:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Call Interception additional network feature
ISO/IEC 15431:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Wireless terminal call handling additional network features
ISO/IEC 15991:2003, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Specification, functional mode
...