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 13874:2003 specifies the signalling protocol for the support of the Path Replacement additional network feature (ANF-PR) at the Q reference point between Private Integrated services Network eXchanges (PINXs) connected together within a Private Integrated Services Network (PISN). ANF-PR is a feature which applies to an established call, allowing that call's connection between PINXs to be replaced by a new connection. 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. ISO/IEC 13874:2003 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 13863. The signalling protocol for ANF-PR 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. ISO/IEC 13874:2003 also specifies additional signalling protocol requirements for the support of interactions at the Q reference point between ANF-PR and other supplementary services and ANFs. ISO/IEC 13874:2003 is applicable to PINXs which can interconnect to form a PISN.

Technologies de l'information — Télécommunications et échange d'information entre systèmes — Réseau privé à intégration de services — Protocole de signalisation d'échange — Caractéristique de réseau additionnelle de remplacement de chemin

General Information

• Status: Published
• Publication Date: 20-Mar-2003
• ICS: 33.040.35 - Telephone networks
• Technical Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Drafting Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 23-May-2025
• Completion Date: 30-Oct-2025

Relations

• Revises: ISO/IEC 13874:1999 - Information technology - Telecommunications and information exchange between systems - Private Integrated Services Network - Inter-exchange signalling protocol - Path replacement additional network feature
• Effective Date: 15-Apr-2008

Overview

ISO/IEC 13874:2003 - "Information technology - Private Integrated Services Network - Inter‑exchange signalling protocol - Path Replacement additional network feature" - defines the Q‑reference‑point signalling protocol to support the Path Replacement additional network feature (ANF‑PR) in QSIG-enabled Private Integrated Services Networks (PISNs). ANF‑PR lets an established call’s connection between Private Integrated services Network eXchanges (PINXs) be replaced by a newly established connection (optionally retaining part of the old path). This document provides the stage‑3 protocol specification and complements service definitions in ISO/IEC 13863.

Key topics and technical requirements

• Scope and applicability: Protocol applies at the Q reference point between PINXs in a PISN and is intended for PINXs that interconnect to form a PISN.
• Protocol layering: ANF‑PR signalling operates on top of basic circuit‑switched call control (ISO/IEC 11572) and reuses generic supplementary‑service procedures (ISO/IEC 11582).
• Roles & states: Defines operational roles (Requesting, Cooperating, Inviting, Transit, Branching, End PINX) and state machines for each role during ANF‑PR procedures.
• Procedures and coding: Message operations, information elements, ASN.1 coding and message sequences for establishing a replacement path; optional procedures to retain parts of the old connection.
• Interactions: Protocol interactions with supplementary services such as Calling/Connected Name Presentation, Call Transfer (SS‑CT), Completion of Calls to Busy/No Reply (SS‑CCBS/SS‑CCNR), Call Forwarding variants, Call Deflection and others.
• Conformance & testing: Protocol Implementation Conformance Statement (PICS) proforma in Annex A, ASN.1 definitions, SDL representations, and example message flows for implementation and test.
• Timers and parameters: Specification includes protocol timers (T1–T4) and operational requirements for reliable switchover.

Applications and who uses it

ISO/IEC 13874:2003 is relevant for:

• PBX/PINX manufacturers implementing QSIG inter‑exchange signalling and ANF‑PR support.
• Telecommunications vendors and system integrators deploying enterprise PISNs requiring call path replacement (e.g., maintenance, rerouting, resilience).
• Network architects and operators designing call continuity and advanced call control behaviors across multi‑vendor private networks.
• Test labs and compliance engineers using the PICS, ASN.1 and SDL artifacts for conformance testing and interoperability verification.

Practical uses include in‑call path migration, network maintenance without dropping active calls, and implementing policy‑driven reconnection logic across corporate telephony networks.

Related standards

• ISO/IEC 13863 (ANF‑PR service specification stages 1–2)
• ISO/IEC 11572 (basic circuit‑switched call control)
• ISO/IEC 11582 (generic supplementary services)
• ISO/IEC 11579‑1 (PISN reference configuration)
• ETS 300 387 (service specification method)

Keywords: ISO/IEC 13874:2003, ANF‑PR, Path Replacement, QSIG, PINX, PISN, inter‑exchange signalling protocol, private network call migration.

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 13874
Third edition
2003-04-01
Information technology —
Telecommunications and information
exchange between systems — Private
Integrated Services Network —
Inter-exchange signalling protocol —
Path Replacement additional network
feature
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Réseau privé à intégration de
services — Protocole de signalisation d'échange — Caractéristique
de réseau additionnelle de remplacement de chemin

Reference number
©
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 Other definitions 2
4.2.1 Branching PINX 2
4.2.2 Cooperating PINX 3
4.2.3 End PINX 3
4.2.4 Preceding PINX 3
4.2.5 Replaced connection 3
4.2.6 Requesting PINX 3
4.2.7 Retained connection 3
4.2.8 Subsequent PINX 3
Inviting PINX
4.2.9 3
5 List of acronyms 3
6 Signalling protocol for the support of ANF-PR 3
6.1 ANF-PR description 3
6.2 ANF-PR operational requirements 4
6.2.1 Requirements on the Cooperating PINX 4
6.2.2 Requirements on the Requesting PINX 4
6.2.3 Requirements on a Transit PINX 4
Requirements on the Inviting PINX
6.2.4 5
6.3 ANF-PR coding requirements 6
6.3.1 Operations 6
6.3.2 Information elements 9
6.3.3 Messages 10
6.4 ANF-PR state definitions 10
6.4.1 States at the Requesting PINX 10
6.4.2 States at the Cooperating PINX 10
6.4.3 States at a Transit PINX on the retained path, including the branching PINX 11
6.4.4 States at the Inviting PINX 11
6.5 ANF-PR signalling procedures 11
6.5.1 Actions at the Requesting PINX 11
6.5.2 Actions at the Cooperating PINX 12
6.5.3 Actions at a Cooperating/Requesting PINX in the case of a trombone connection 13
6.5.4 Actions at a Transit PINX 13
6.5.5 Actions at Inviting PINX 13
6.6 ANF-PR optional signalling procedures for retention of part of the old connection 14
Actions at the Requesting PINX
6.6.1 14
© ISO/IEC 2003 – All rights reserved iii

6.6.2 Actions at the Cooperating PINX 14
6.6.3 Actions at a Transit PINX on the retained connection 14
6.6.4 Actions at a Transit PINX on the new connection or replaced connection 16
6.6.5 Actions at Inviting PINX on the retained connection 16
6.7 ANF-PR impact of interworking with public ISDNs 16
6.8 ANF-PR impact of interworking with non-ISDNs 16
6.9 Protocol interactions between ANF-PR and other supplementary services and ANFs 16
6.9.1 Interaction with Calling Name Identification Presentation (SS-CNIP) 16
6.9.2 Interaction with Connected Name Identification Presentation (SS-CONP) 16
6.9.3 Interaction with Completion of Calls to Busy Subscriber (SS-CCBS) 17
6.9.4 Interaction with Completion of Calls on No Reply (SS-CCNR) 17
6.9.5 Interaction with Call Transfer (SS-CT) 17
Interaction with Call Forwarding Unconditional (SS-CFU)
6.9.6 18
6.9.7 Interaction with Call Forwarding Busy (SS-CFB) 18
6.9.8 Interaction with Call Forwarding No Reply (SS-CFNR) 18
6.9.9 Interaction with Call Deflection (SS-CD) 18
6.10 ANF-PR parameter values (timers) 18
6.10.1 Timer T1 18
6.10.2 Timer T2 18
6.10.3 Timer T3 18
Timer T4
6.10.4 19
Annexes
A - Protocol Implementation Conformance Statement (PICS) proforma 20
B - Imported ASN.1 definitions 27
C - Examples of message sequences 28
D - Specification and Description Language (SDL) representation of procedures 36
E - ASN.1 definitions according to ITU-T Recs. X.208 / X.209 42
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 13874 was prepared by ECMA (as ECMA-176) 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 third edition cancels and replaces the second edition (ISO/IEC 13874:1999), 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 Path Replacement
additional network feature. The protocol defined in this 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 13874:2003(E)

Information technology — Telecommunications and information
exchange between systems — Private Integrated Services Network —
Inter-exchange signalling protocol — Path Replacement additional
network feature
1Scope
This International Standard specifies the signalling protocol for the support of the Path Replacement additional network feature
(ANF-PR) at the Q reference point between Private Integrated services Network eXchanges (PINXs) connected together within
a Private Integrated Services Network (PISN).
ANF-PR is a feature which applies to an established call, allowing that call's connection between PINXs to be replaced by a
new connection.
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 13863.
The signalling protocol for ANF-PR 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 ANF-PR and other supplementary services and ANFs.
This International Standard is applicable to PINXs which 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.
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 11571:1998, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Networks - Addressing
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 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 13863:1998, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Specification, functional model and information flows - Path replacement additional network
feature
© ISO/IEC 2003 – All rights reserved 1

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 15056:1997, Information technology - Telecommunications and information exchange between systems - Private
Integrated Services Network - Inter-exchange signalling protocol - Transit counter additional network feature
ETS 300 387:1994, Private Telecommunication Network (PTN); Method for the specification of basic and supplementary
services
ITU-T Rec. I.112:1993, Vocabulary of terms for ISDNs
ITU-T Rec. I.210:1993, Principles of telecommunication services supported by an ISDN and the means to describe them
ITU-T Rec. Q.950:2000, Supplementary services protocols, structure and general principles
ITU-T Rec. Z.100:1999, Specification and description language (SDL)
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1 External definitions
This International Standard uses the following terms defined in other documents:
− ANF-PR user (ISO/IEC 13863)
− Application Protocol Data Unit (APDU) (ISO/IEC 11582)
− Basic Service (ITU-T Rec. I.210)
− Call, Basic Call (ISO/IEC 11582)
− Connection (ISO/IEC 13863)
− Incoming Gateway PINX (ISO/IEC 11572)
− Interpretation APDU (ISO/IEC 11582)
− Network Facility Extension (NFE) (ISO/IEC 11582)
− New Connection (ISO/IEC 13863)
− Old Connection (ISO/IEC 13863)

− Originating PINX (ISO/IEC 11572)
− Outgoing Gateway PINX (ISO/IEC 11572)
− Private Integrated Services Network (PISN) (ISO/IEC 11579-1)
− Private Integrated services Network eXchange (PINX) (ISO/IEC 11579-1)
− Signalling (ITU-T Rec. I.112)
− Supplementary Service (ITU-T Rec. I.210)
− Supplementary Services Control Entity (ISO/IEC 11582)
− Terminating PINX (ISO/IEC 11572)
− Transit PINX (ISO/IEC 11572)
− Trombone Connection (ISO/IEC 13863)
− User (except in the context of ANF-PR user) (ISO/IEC 11574)
4.2 Other definitions
4.2.1 Branching PINX
The Transit PINX at which the retained connection finishes and the new connection starts.
2 © ISO/IEC 2003 – All rights reserved

4.2.2 Cooperating PINX
The end PINX which initiates the establishment of the new connection towards other end PINX involved in the call.
4.2.3 End PINX
Within the context of a call, a PINX which is not acting as a Transit PINX, i.e., an Originating PINX, a Terminating PINX, an
Incoming Gateway PINX or an Outgoing Gateway PINX.
4.2.4 Preceding PINX
The adjacent PINX in the direction of the Cooperating PINX, relative to a particular PINX involved in the old connection.
NOTE 1 - This can be the Cooperating PINX itself or a Transit PINX.
4.2.5 Replaced connection
That part of the old connection which is not retained and is replaced by the new connection.
4.2.6 Requesting PINX
The end PINX which invokes ANF-PR and towards which the new connection is routed.
4.2.7 Retained connection
That part of the old connection which is retained and not replaced by the new connection.
4.2.8 Subsequent PINX
The adjacent PINX in the direction of the Requesting PINX, relative to a particular PINX involved in the old connection.
NOTE 2 - This can be the Requesting PINX itself or a Transit PINX.
4.2.9 Inviting PINX
Any PINX in the connection that is associated with the ANF-PR user and able to request either end PINX to invoke ANF-PR.
5 List of acronyms
ANF Additional Network Feature
ANF-PR Path Replacement additional network feature
APDU Application Protocol Data Unit
ASN.1 Abstract Syntax Notation no. 1
ISDN Integrated Services Digital Network
NFE Network Facility Extension
PICS Protocol Implementation Conformance Statement
PINX Private Integrated services Network eXchange
PISN Private Integrated Services Network
SDL Specification and Description Language
SS-CT Call Transfer supplementary service
6 Signalling protocol for the support of ANF-PR
6.1 ANF-PR description
ANF-PR is invoked by an established call, allowing that call's connection through the PISN to be replaced by a new connection.
Optionally, the direction of the new connection may be decided by the ANF-PR user. If the new connection is required to
satisfy certain criteria, ANF-PR should be used in conjunction with other supplementary services and/or ANFs. In the absence
of specific criteria, the new connection should be established using the routeing rules which apply to basic call establishment.
NOTE 3 - Annex A of ISO/IEC 13863 gives examples of the circumstances under which ANF-PR can be used and criteria which can govern
the selection of the new connection.
ANF-PR may be initiated locally at the Requesting PINX or optionally from an Inviting PINX. The Requesting PINX shall
request the Cooperating PINX to attempt the establishment of a new connection from the Cooperating PINX to the Requesting
PINX. If successful, the new connection shall replace the old connection.
© ISO/IEC 2003 – All rights reserved 3

NOTE 4 - The Requesting PINX can be either end PINX involved in a call, i.e., the Originating PINX or the Terminating PINX or, in the
case of interworking with another network, the Incoming Gateway PINX or Outgoing Gateway PINX.
Optional procedures and coding are specified for allowing the retention of one or more elements of the old connection, starting
from the Cooperating PINX and continuing as far as a Transit PINX, subject to any given criteria being achievable in that way.
A new connection is established from the Transit PINX to the Requesting PINX instead of from the Cooperating PINX to the
Requesting PINX.
6.2 ANF-PR operational requirements
6.2.1 Requirements on the Cooperating PINX
ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, is Active.
NOTE 5 - State Active will have been reached as a result of ISO/IEC 11572 call establishment procedures, possibly in conjunction with
supplementary service and/or ANF procedures.
ISO/IEC 11572 protocol control procedures for call establishment at the outgoing side of an inter-PINX link shall apply to the
establishment of the new connection. ISO/IEC 11572 protocol control procedures for call clearing shall apply to the release of
the old connection in the event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for an end PINX,
shall apply.
6.2.2 Requirements on the Requesting PINX
ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, is Active.
NOTE 6 - State Active will have been reached as a result of ISO/IEC 11572 call establishment procedures, possibly in conjunction with
supplementary service and/or ANF procedures.
ISO/IEC 11572 protocol control procedures for call establishment at the incoming side of an inter-PINX link shall apply to the
establishment of the new connection. ISO/IEC 11572 protocol control procedures for call clearing shall apply to the release of
the old connection in the event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for an end PINX,
shall apply.
6.2.3 Requirements on a Transit PINX
6.2.3.1 Transit PINX involved in the replaced connection
ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, on each of the two links
(incoming and outgoing) is Active and whose call control state, as defined in ISO/IEC 11572 is TCC_Call_Active.
NOTE 7 - State Active will have been reached as a result of ISO/IEC 11572 call establishment procedures, possibly in conjunction with
supplementary service and/or ANF procedures.
ISO/IEC 11572 protocol control and call control procedures for call clearing at a Transit PINX shall apply to the release of the
old connection in the event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for a Transit PINX,
shall apply. For ANF-PR the requirements are limited to the passing on of Facility information elements for which the
destination, as indicated in the Network Facility Extension (NFE), is not the Transit PINX.
6.2.3.2 Transit PINX involved in the new connection
ISO/IEC 11572 protocol control and call control procedures for call establishment at a Transit PINX shall apply to the
establishment of the new connection.
ISO/IEC 11572 protocol control and call control procedures for call clearing at a Transit PINX shall apply to the release of the
new connection in the event of failure to complete ANF-PR successfully.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for a Transit PINX,
shall apply. For ANF-PR the requirements are limited to the passing on of Facility information elements for which the
destination, as indicated in the Network Facility Extension (NFE), is not the Transit PINX.
6.2.3.3 Transit PINX involved in the retained connection
The procedures below are applicable only if the optional procedures for retention of part of the old connection (55) are
supported.
4 © ISO/IEC 2003 – All rights reserved

ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, on each of the two links
(incoming and outgoing) is Active and whose call control state, as defined in ISO/IEC 11572 is TCC_Call_Active.
NOTE 8 - State Active will have been reached as a result of ISO/IEC 11572 call establishment procedures, possibly in conjunction with
supplementary service and/or ANF procedures.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for a Transit PINX,
shall apply.
6.2.3.4 Branching PINX
The procedures below are applicable only if the optional procedures for retention of part of the old connection (55) are
supported.
ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, on each of the two links
(incoming and outgoing) is Active and whose call control state, as defined in ISO/IEC 11572 is TCC_Call_Active.
NOTE 9 - State Active will have been reached as a result of ISO/IEC 11572 call establishment procedures, possibly in conjunction with
supplementary service and/or ANF procedures.
ISO/IEC 11572 protocol control procedures for call establishment at the outgoing side of an inter-PINX link shall apply to the
establishment of the new connection. ISO/IEC 11572 protocol control procedures for call clearing shall apply to the release of
the replaced connection in the event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in ISO/IEC 11582 for a Transit PINX,
shall apply.
6.2.4 Requirements on the Inviting PINX
ANF-PR shall be applicable to a call whose protocol control state, as defined in ISO/IEC 11572, is Active. Generic procedures
for the call-related control of supplementary services, as specified in ISO/IEC 11582 for an end PINX, shall apply.
© ISO/IEC 2003 – All rights reserved 5

6.3 ANF-PR coding requirements
6.3.1 Operations
The operations defined in Abstract Syntax Notation number 1 (ASN.1) in table 1 shall apply. The notation is in accordance
with ITU-T Rec. X.680 and X.690. The ITU-T Rec. X.208 and X.209 superseded version is in annex E.
Table 1 - Operations in support of ANF-PR
Path-Replacement-Operations-asn1-97
{iso standard pss1-path-replacement (13874) pr-operations-asn1-97(1)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
IMPORTS OPERATION, ERROR FROM Remote-Operations-Information-Objects
{joint-iso-itu-t (2) remote-operations(4) informationObjects(5) version1(0)}
EXTENSION, Extension{} FROM Manufacturer-specific-service-extension-class-asn1-97
{iso standard
pss1-generic-procedures (11582) msi-class-asn1-97 (11)}
notAvailable, supplementaryServiceInteractionNotAllowed
FROM General-Error-List
{ccitt recommendation q 950 general-error-list (1)}
PartyNumber FROM Addressing-Data-Elements-asn1-97
{iso(1) standard(0) pss1-generic-procedures(11582)
addressing-data-elements-asn1-97 (20)};
Path-Replacement-Operations OPERATION ::={
pathReplacePropose | pathReplaceSetup | pathReplaceRetain | pathReplaceInvite}
pathReplaceInvite OPERATION ::= {
ARGUMENT DummyArg
RETURN RESULT FALSE
ERRORS {
notAvailable |
temporarilyUnavailable |
supplementaryServiceInteractionNotAllowed |
criteriaPermanentlyUnachievable |
criteriaTemporarilyUnachievable |
invalidRerouteingNumber |
unrecognizedCallIdentity |
establishmentFailure |
collision |
unspecified }
ALWAYS RESPONDS FALSE
CODE local: 86 }
6 © ISO/IEC 2003 – All rights reserved

Table 1 - Operations in support of ANF-PR (continued)
pathReplacePropose OPERATION ::= {
ARGUMENT PRProposeArg
RETURN RESULT FALSE
ERRORS {
notAvailable |
temporarilyUnavailable |
supplementaryServiceInteractionNotAllowed |
criteriaPermanentlyUnachievable |
criteriaTemporarilyUnachievable |
invalidRerouteingNumber |
unrecognizedCallIdentity |
establishmentFailure |
collision |
unspecified }
ALWAYS RESPONDS FALSE
CODE local: 4 }
pathReplaceSetup OPERATION ::= {
ARGUMENT PRSetupArg
RESULT DummyResult
ERRORS {
criteriaPermanentlyUnachievable |
criteriaTemporarilyUnachievable |
invalidRerouteingNumber |
unrecognizedCallIdentity |
temporarilyUnavailable |
unspecified }
CODE local: 5 }
pathReplaceRetain OPERATION ::= {
ARGUMENT PRRetainArg
RESULT DummyResult
ERRORS {
notAvailable |
temporarilyUnavailable |
supplementaryServiceInteractionNotAllowed |
criteriaPermanentlyUnachievable |
criteriaTemporarilyUnachievable |
invalidRerouteingNumber |
unrecognizedCallIdentity |
establishmentFailure |
unspecified }
CODE local: 6 }
© ISO/IEC 2003 – All rights reserved 7

Table 1 - Operations in support of ANF-PR (continued)
PRProposeArg ::= SEQUENCE {
callIdentity CallIdentity,
rerouteingNumber PartyNumber,
extension CHOICE {
single [1] IMPLICIT Extension{{PRExtSet}},
multiple [2] IMPLICIT SEQUENCE OF Extension{{PRExtSet}}
} OPTIONAL
}
PRSetupArg ::= SEQUENCE {
callIdentity CallIdentity,
extension CHOICE {
single [1] IMPLICIT Extension{{PRExtSet}},
multiple [2] IMPLICIT SEQUENCE OF Extension{{PRExtSet}}
} OPTIONAL
}
PRRetainArg ::= SEQUENCE {
callIdentity CallIdentity,
rerouteingNumber PartyNumber,
extension CHOICE {
single [1] IMPLICIT Extension{{PRExtSet}},
multiple [2] IMPLICIT SEQUENCE OF Extension{{PRExtSet}}
} OPTIONAL
}
DummyResult ::= CHOICE {
null NULL,
single [1] IMPLICIT Extension{{PRExtSet}},
multiple [2] IMPLICIT SEQUENCE OF Extension{{PRExtSet}}
}
DummyArg ::= CHOICE {
null NULL,
single [1] IMPLICIT Extension{{PRExtSet}},
multiple [2] IMPLICIT SEQUENCE OF Extension{{PRExtSet}}
}
PRExtSet EXTENSION ::= {…}
CallIdentity ::= NumericString (SIZE(1.4))
temporarilyUnavailable ERROR ::= {CODE local: 1000}
-- used when the operation is temporarily not available and none of
-- the other errors applies - a later attempt could be successful
collision ERROR ::= {CODE local: 1001}
-- used when a pathReplacePropose invoke APDU is received by a PINX
-- which has sent a pathReplacePropose invoke APDU
8 © ISO/IEC 2003 – All rights reserved

Table 1 - Operations in support of ANF-PR (concluded)
criteriaPermanentlyUnachievable ERROR ::= {CODE local: 1002}
-- used when the special criteria requested cannot be achieved
-- because the necessary resources are permanently unavailable
criteriaTemporarilyUnachievable ERROR ::= {CODE local: 1003}
-- used when the special criteria requested cannot be achieved
-- because the necessary resources are temporarily unavailable
-- a later attempt could be successful
invalidRerouteingNumber ERROR ::= {CODE local: 1004}
-- used when the establishment of the new connection fails because the
-- Called party number information element is not a valid number for
-- routeing the new connection to
unrecognizedCallIdentity ERROR ::= {CODE local: 1005}
-- used when establishment of the new connection fails because it could
-- not be associated with the old connection at the Requesting PINX
establishmentFailure ERROR ::= {CODE local: 1006}
-- used when establishment of the new connection fails and no other error
-- applies
unspecified ERROR ::= {
PARAMETER Extension{{PRExtSet}}
CODE local: 1008}
-- used to convey a manufacturer specific error, possibly with other information
-- of Path-Replacement-Operations
END -- of Path-Replacement-Operations-asn1-97
6.3.2 Information elements
6.3.2.1 Facility information element
APDUs of the operations defined in 6.3.1 shall be coded in the Facility information element in accordance with
ISO/IEC 11582.
When conveying the invoke APDU of operation pathReplaceInvite, the NFE shall be included and the destinationEntity data
element of the NFE shall contain value endPINX.
When conveying APDUs of operations pathReplacePropose and pathReplaceSetup, the NFE shall be included.
When conveying the invoke APDU of operation pathReplacePropose, the destinationEntity data element of the NFE shall
contain value endPINX.
When conveying the invoke APDU of operation pathReplaceSetup, the destinationEntity data element of the NFE shall contain
value endPINX.
When conveying the invoke APDU of operation pathReplaceRetain, the NFE shall be omitted.
When conveying the invoke APDU of operation pathReplaceSetup, the Interpretation APDU shall be included and shall have
the value clearCallIfAnyInvokePduNotRecognised. When conveying any other Remote Operations APDU, the Interpretation
APDU shall either be omitted or have the value rejectAnyUnrecognisedInvokePdu.
© ISO/IEC 2003 – All rights reserved 9

6.3.2.2 Other information elements
The following information elements used during establishment of the new connection and release of the old connection shall be
coded as specified in ISO/IEC 11572:
− Bearer capability
− Called party number
− Cause
− Sending complete
The following information element shall be coded as specified in ISO/IEC 15056:
− Transit Counter
6.3.3 Messages
Except for cases where a basic call message is to be conveyed at the same time, the Facility information shall be conveyed in a
FACILITY message as specified in ISO/IEC 11582.
The following messages used during establishment of the new connection and release of the old connection shall be as specified
in ISO/IEC 11572:
− CALL PROCEEDING
− CONNECT
− CONNECT ACKNOWLEDGE
− DISCONNECT
− RELEASE
− RELEASE COMPLETE
− SETUP
6.4 ANF-PR state definitions
6.4.1 States at the Requesting PINX
The procedures for the Requesting PINX are written in terms of the following conceptual states existing within the ANF-PR
functional entity in that PINX in association with a particular call.
6.4.1.1 State PR-Req-Idle
ANF-PR is not operating.
6.4.1.2 State PR-Req-Initiated
A pathReplacePropose invoke APDU has been sent to the Cooperating PINX.
6.4.1.3 State PR-Req-Completing
The new connection has been established and a pathReplaceSetup return result APDU has been sent to the Cooperating PINX.
6.4.2 States at the Cooperating PINX
The procedures for the Cooperating PINX are written in terms of the following conceptual states existing within the ANF-PR
functional entity in that PINX in association with a particular call.
6.4.2.1 State PR-Coop-Idle
ANF-PR is not operating.
6.4.2.2 State PR-Coop-Establishment
A pathReplaceSetup invoke APDU has been sent in conjunction with the establishment of the new connection.
6.4.2.3 State PR-Coop-Retain
A pathReplaceRetain invoke APDU has been sent to the subsequent PINX.
10 © ISO/IEC 2003 – All rights reserved

6.4.3 States at a Transit PINX on the retained path, including the branching PINX
The procedures for a Transit PINX on the retained path are written in terms of the following conceptual states existing within
the ANF-PR functional entity in that PINX in association with a particular call.
6.4.3.1 State PR-Transit-Idle
ANF-PR is not operating.
6.4.3.2 State PR-Transit-Establishment
A pathReplaceSetup invoke APDU has been sent in conjunction with the establishment of the new connection.
6.4.3.3 State PR-Transit-Retain
A pathReplaceRetain invoke APDU has been sent to the subsequent PINX.
6.4.4 States at the Inviting PINX
6.4.4.1 State PR-invite-Idle
ANF-PR is not operating.
6.5 ANF-PR signalling procedures
The signalling procedures specified below are in support of replacement of the entire connection. Additional optional
procedures for retention of part of the old connection are specified in 6.6.
Examples of message sequences are shown in C.1 to C.4 of annex C.
6.5.1 Actions at the Requesting PINX
The SDL representation of procedures at the Requesting PINX is shown in D.2 of annex D.
6.5.1.1 ANF PR initiated by the Requesting PINX
The procedures of 6.5.1.3 and 6.5.1.4 shall apply.
6.5.1.2 Optional support of a request from an Inviting PINX
On receipt of a FACILITY message containing a pathReplaceInvite invoke APDU, the Requesting PINX shall apply the
procedures of 6.5.1.3 and 6.5.1.4 with the following additions.
If the Requesting PINX is unable to act on the pathReplaceInvite invoke APDU while in state PR-Req-Idle, a FACILITY
message containing pathReplaceInvite return error APDU may be returned. No state change shall occur.
While in state PR-Req-Initiated or PR-Req-Completing, a FACILITY message containing a pathReplaceInvite invoke shall be
ignored.
On receipt of a FACILITY message containing a pathReplacePropose return error while in state PR-Req-Initiated, a
pathReplaceInvite return error APDU may be returned to the Inviting PINX.
6.5.1.3 Normal procedures
Examples of message sequences are shown in C.1 and C.3 of annex C.
The Requesting PINX shall send a pathReplacePropose invoke APDU in a FACILITY message to the Cooperating PINX and
enter state PR-Req-Initiated. Within the argument, the rerouteingNumber data element shall contain a number from one of the
native number plans of the PISN (see ISO/IEC 11571). The number, when used as the contents of information element Called
party number in a SETUP message, shall be sufficient to cause routeing of the new connection to the Requesting PINX. The
callIdentity data element shall contain a number which, in conjunction with the rerouteingNumber data element, identifies the
particular ANF-PR entity, and therefore the call on which ANF-PR is being invoked. This number need not have significance
outside the Requesting PINX.
NOTE 10 - The number in the callIdentity data element should be sufficient to distinguish the call concerned from any other call for which
the PINX is acting as an ANF-PR Requesting PINX at that time.
Having agreed the B-channel and sent back a CALL PROCEEDING message in response to an incoming SETUP message, in
accordance with the procedures of ISO/IEC 11572, if the SETUP contains a pathReplaceSetup invoke APDU the Requesting
PINX shall proceed as follows. If the callIdentity data element in the argument of pathReplaceSetup, in conjunction with the
number information in the Called party number information element, identifies an ANF-PR entity in state PR-Req-Initiated, the
Requesting PINX shall associate the new connection (as requested by the SETUP message) with the call on whose behalf that
ANF-PR entity is acting.
© ISO/IEC 2003 – All rights reserved 11

The Requesting PINX shall connect the calling / called user to the B-channel of the new connection and terminate the
B-channel of the old connection in a suitable manner (pending its release).
NOTE 11 - The method of terminating the old connection's B-channel is an implementation matter. Annex B of ISO/IEC 13863 contains
more information on this.
A pathReplaceSetup return result APDU shall be sent in a CONNECT message using the call reference of the new connection
and state PR-Req-Completing shall be entered.
NOTE 12 - On sending CONNECT, the protocol control state for the new connection will become Active.
While in state PR-Req-Completing, if a DISCONNECT message is received using the call reference of the old connection, the
Requesting PINX shall complete the release of the old connection in accordance with the procedures of ISO/IEC 11572, and
enter state PR-Req-Idle. The call shall continue as an active call using the new connection.
6.5.1.4 Exceptional procedures
Examples of message sequences are shown in C.2 and C.4 of annex C.
Receipt of a FACILITY message containing a pathReplacePropose return error APDU or reject APDU during state PR-Req-
Initiated shall cause entry to state PR-Req-Idle, thereby abandoning ANF-PR. The call shall continue to use the old connection.
NOTE 13 - Depending on the error, it may be appropriate to invoke ANF-PR again later. If the error is collision, steps should be taken to
reduce the probability of a further collision, e.g., by using a random delay before invoking again.
Failure to associate an incoming SETUP message containing a pathReplaceSetup invoke APDU with an ANF-PR entity in state
PR-Req-Initiated shall result in the sending of a DISCONNECT message to initiate the clearing of the new connection.
Depending on implementation, the DISCONNECT message shall contain either:
− a suitable cause number in the Cause information element, e.g., 1 "unallocated (unassigned) number"; or
− cause number 29 "facility rejected" in the Cause information element and a return error APDU containing error
invalidRerouteingNumber; or
− cause number 29 "facility rejected" in the Cause information element and a return error APDU containing error
unrecognizedCallIdentity.
If the incoming SETUP message containing a pathReplaceSetup invoke APDU is successfully associated with an ANF-PR
entity in state PR-Req-Initiated but the new connection is unsuitable for some reason, e.g., criteria not satisfied, a
DISCONNECT message shall be sent to initiate clearing of the new connection. The DISCONNECT message shall contain
cause number 29 "facility rejected" in the Cause information element and a return error APDU containing an appropriate error.
The ANF-PR entity shall remain in state PR-Req-Initiated.
NOTE 14 - Receipt of a pathReplacePropose return error APDU can be expected.
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU while in state PR-Req-Initiated, a
pathReplacePropose return error APDU containing error collision shall be returned. No state change shall occur.
NOTE 15 - Receipt of a pathReplacePropose return error APDU containing error collision can be expected.
While in state PR-Req-Completing, if a DISCONNECT message is received using the call reference of the new connection, the
Requesting PINX shall complete the release of the new connection in accordance with the procedures of ISO/IEC 11572,
reconnect the calling / called user to the B-channel of the old connection, and enter state PR-Req-Idle.
6.5.2 Actions at the Cooperating PINX
The SDL representation of procedures at the Cooperating PINX is shown in D.3 of annex D.
6.5.2.1 Normal procedures
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU while in protocol control state Active and
ANF-PR state PR-Coop-Idle, the Cooperating PINX shall determine whether it can proceed with ANF-PR. If so, it shall
attempt to establish a new connection by selecting an outgoing B-channel on a route determined by the contents of the
rerouteingNumber data element within the received argument. If a B-channel is available, a SETUP message shall be sent using
a new call reference in accordance with the procedures of ISO/IEC 11572. The SETUP shall contain a new call reference and
the following information elements.
− Bearer capability, containing bearer capability information as for the old connection;
− Called party number, containing the number received in the rerouteingNumber data element within the - received argument;
12 © ISO/IEC 2003 – All rights reserved

− Sending complete;
− Facility;
− Optionally, Transit Counter with the transit count field set to zero.
The Facility information element shall contain a pathReplaceSetup invoke APDU. Within the argument, data element
callIdentity shall have the same contents as the corresponding data element in the argument of the received pathReplacePropose
invoke APDU.
The Cooperating PINX shall terminate the new connection's B-channel suitably.
NOTE 16 - The method of terminating the new connection's B-channel is an implementation matter. Annex B of ISO/IEC 13863 contains
more information on this.
State PR-Coop-Establishment shall be entered.
The protocol control procedures of ISO/IEC 11572 shall apply during the establishment of the new connection.
NOTE 17 - Initially protocol control will enter state Call Initiated. On receipt of a CALL PROCEEDING message, state Outgoing Call
Proceeding will be entered and on receipt of CONNECT, state Active will be entered.
On receipt of a CONNECT message (using the call reference of the new connection) containing a pathReplaceSetup return
result APDU, the Cooperating PINX shall disconnect the B-channel of the old connection and connect the calling / called user
instead to the B-channel of the new connection. A DISCONNECT message shall be sent using the call reference of the old
connection, thereby initiating the clearing procedures of ISO/IEC 11572 for the old connection. State PR-Coop-Idle shall be
entered. The call shall continue as an active call using the new connection.
6.5.2.2 Exceptional procedures
If the Cooperating PINX is unable to comply with the pathReplacePropose invoke APDU, it shall send back a FACILITY
message containing a pathReplacePropose return error APDU with a suitable error.
If the new connection fails to be established for any reason, the Cooperating PINX shall send using the old connection a
FACILITY message containing a pathReplacePropose return error APDU with a suitable error. Reasons can include:
− unable to select a B-channel for the new connection;
− receipt of a call clearing message using the new connection's call reference without a pathReplaceSetup return error APDU
or reject APDU;
− receipt of a call clearing message using the new connection's call reference with a pathReplaceSetup return error APDU or
reject APDU;
− timer expiry at the Cooperating PINX.
In each case state PR-Coop-Idle shall be entered and the call shall continue as an active call using the old connection.
On receipt of a FACILITY message containing a pathReplaceInvite invoke APDU while in state PR-Coop-Retain or PR-Coop-
Establishment, a FACILITY message containing a pathReplaceInvite return error APDU may be returned to the Inviting PINX.
No state change should occur.
6.5.3 Actions at a Cooperating/Requesting PINX in the case of a trombone connection
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU, the Cooperating PINX can determine
from the rerouteingNumber data element in the argument whether the Requesting PINX is the same as the Cooperating PINX,
i.e., whether a trombone connection exists.
In the case of a trombone connection, establishment of the new connection and switching over to it will be intra-PINX matters.
The only further signalling which will occur at the Q reference point will be the clearing of the old connection.
6.5.4 Actions at a Transit PINX
No special actions are required in support of ANF-PR.
6.5.5 Actions at Inviting PINX
The SDL representation of procedures at the Inviting PINX is shown in D.1 of annex D.
© ISO/IEC 2003 – All rights reserved 13

6.5.5.1 Normal procedures
On determining that ANF-PR is to be invoked during a call whose protocol control state is Active, the Inviting PINX shall send
a pathReplaceInvite invoke APDU in a FACILITY message to the Requesting PINX. If the old connection is cleared it shall be
interpreted as ANF-PR is successful.
6.5.5.2 Exceptional procedures
On receipt of a FACILITY message containing a pathReplaceInvite return error or reject APDU the action shall be
implementation dependent.
NOTE 18 - Depending on the error, it may be appropriate to invoke ANF-PR again later or invoke ANF-PR in the other direction. If the
error is collision, steps should be taken to reduce the probability of a further collision, e.g., by using a random delay before invoking again.
6.6 ANF-PR optional signalling procedures for retention of part of the old connection
Examples of message sequences are shown in C.5 to C.7 of annex C.
6.6.1 Actions at th
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