SIST EN 300 359-1 V1.3.2:2005

• Abstract:

  To introduce amendment to CCBS B-queue processing Supporting Members: Italtel, Tele Danmark, France Telecom, Siemens Ag, Ericsson

• 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 300 359-1 V1.3.2 (2000-06) - Integrated Services Digital Network (ISDN); Completion of Calls to Busy Subscriber (CCBS) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification

SIST EN 300 359-1 V1.3.2:2005 specifies the stage 3 protocol for Integrated Services Digital Network (ISDN) Completion of Calls to Busy Subscriber (CCBS) using Digital Subscriber Signalling System No. one (DSS1). It defines the signalling procedures, state handling, timers and ASN.1 operations that let a busy call to destination B be completed later when B becomes free, for equipment at the T reference point or coincident S and T reference point.

The Slovenski standard is identical to EN 300 359-1 Version 1.3.2.

What does SIST EN 300 359-1 V1.3.2:2005 specify?

SIST EN 300 359-1 V1.3.2:2005 specifies the stage 3 aspects of the CCBS supplementary service for pan-European ISDN. In practice, that means the DSS1 protocol procedures and switching functions needed to support the service, including use through an intermediate private ISDN at the T reference point.

The document applies to equipment that supports CCBS when attached at either side of a T reference point or coincident S and T reference point. It does not cover the extra protocol requirements for providing the service through a non-ISDN telecommunications network.

The document is organized into clauses for scope, references, definitions, abbreviations, service description, operational requirements, coding requirements, state definitions, signalling procedures, interworking with private ISDNs, interactions, timer values and SDL diagrams. Its annexes separate signalling flows, status request rules, object identifier values and the change record.

Annex	What it covers
Annex A	CCBS signalling flows for the main operating cases
Annex B	Provision of status request procedures
Annex C	Assignment of object identifier values
Annex D	Change record

What are the key requirements of SIST EN 300 359-1 V1.3.2:2005?

SIST EN 300 359-1 V1.3.2:2005 describes how the network must remember a busy call, monitor destination B, recall user A when B becomes free, and then set up the CCBS call automatically. For implementers, this is the core call-back behavior that must work across the user side and the network side.

Service provision and options

Clause 6 allows CCBS to be offered by subscription or as a general service, and withdrawal can be by the subscriber or for administrative reasons. The standard also defines service options that matter operationally: global recall versus specific recall, whether the network checks for identical calls, and whether CCBS request retention is supported if B becomes busy again.

These options affect who receives the recall, whether a repeated request is rejected as duplicate, and whether the original request stays active in queue B. In practice, the operator has to configure these options consistently across the access.

Call information retention and activation

Clause 9 requires network A to retain the basic call information from the failed call, including bearer capability, high layer compatibility, low layer compatibility, calling party address and called party address. It also retains the call failure reason and the CCBS available indication so it can decide whether CCBS may be activated.

To start CCBS, user A sends a CCBSRequest with a callLinkageID. If activation succeeds, network A assigns a cCBSReference, returns it to user A, places the request in queue A and starts timer T-CCBS2. That reference is used later to interrogate, deactivate or complete the service.

Error handling and deactivation

The protocol defines specific failure cases such as outgoingCCBSQueueFull, cCBSIsAlreadyActivated, supplementaryServiceInteractionNotAllowed, longTermDenial and shortTermDenial. These outcomes tell the user whether the request failed because of capacity, duplicate activation, interaction rules or CCBS availability.

Timers also control how long the service remains active and how long the user waits for responses. T-ACTIVATE, T-DEACTIVATE and T-INTERROGATE are user-side waiting times, so implementations must time out transactions cleanly instead of waiting indefinitely.

Queue B processing and B-free detection

Clause 9.5 defines queue B processing at network B. Network B monitors destination B, reserves a B-channel after timer T-CCBS4, and then decides whether B is free enough to trigger recall or call setup.

The status request procedure is important here. Annex B and clause 9.5 distinguish between services where status requests are not supported for existing services and those where they are supported for all bearer capabilities. That affects whether network B can use compatible-terminal checks or must wait for all B-channels to be free.

When a CCBS call is pending, identical incoming calls can be rejected with cause #34 if the reserved channel must be protected for the CCBS request. Practically, this prevents the waiting CCBS call from being displaced by a normal incoming call to the same destination.

Interworking with private ISDNs

Clause 10 defines the extra procedures when CCBS passes through a private ISDN. The protocol uses operations such as CCBS-T-Request, CCBS-T-Call, CCBS-T-Suspend, CCBS-T-Resume, CCBS-T-RemoteUserFree and CCBS-T-Available.

These procedures separate the originating side, the destination side and the public network behavior. For system integration, this is the part that shows how public and private networks exchange CCBS status, suspend and resume information, and how request retention is handled when both sides support it.

Timer values and dynamic behavior

Clause 13 gives the timer framework used by the service, including the retention timer, status check timers, CCBS service duration timers, recall timer and idle guard timer. The practical value is that implementers know the waiting windows for retention, recall and re-try behavior.

Clause 14 adds SDL diagrams that show the dynamic behavior of the user, network A, network B and private-network processes. These diagrams are the operational map for software designers and test engineers.

What terms does SIST EN 300 359-1 V1.3.2:2005 define?

CCBS busy is the condition where user A cannot accept a CCBS-related event because the access is already full, has no free B-channels, or already has a CCBS recall pending.

call information retention is the procedure by which network A stores the basic information from the failed call so it can later set up an equivalent CCBS call.

CCBS request retention is the option that keeps an original CCBS request in queue B when B becomes busy again after an attempt to complete the call.

queue A is the buffer in network A used to control CCBS requests associated with user A on a per-ISDN-number basis.

queue B is the buffer in network B used to control CCBS requests associated with destination B and to monitor when user B becomes not busy.

existing service means a basic telecommunication service associated with speech, 3,1 kHz audio or 64 kbit/s unrestricted bearer capability.

global recall means the CCBS recall is offered to all compatible terminals, while specific recall means it is offered only to the terminal that activated CCBS.

Who uses SIST EN 300 359-1 V1.3.2:2005?

SIST EN 300 359-1 V1.3.2:2005 is used by ISDN service providers, network operators, switch and gateway vendors, and test laboratories that need to implement or verify CCBS behavior. It is also relevant to quality managers and buyers who need to confirm that an ISDN product supports the correct DSS1 signalling for busy-line callback.

In practice, users apply it to implementation design, interoperability checks, conformance testing, and troubleshooting of activation, recall and call establishment behavior. It is especially relevant where public ISDN and private ISDN interwork.

What changed in SIST EN 300 359-1 V1.3.2:2005 from the previous edition?

SIST EN 300 359-1 V1.3.2:2005 replaces EN 300 359-1 V1.2.4 and earlier ETS 300 359-1 editions. The change record states these updates:

• modification of subclause 9.5.1.1 on determining that CCBS is available
• modification of subclause 9.5.3.1 on queue B processing
• conversion to EN layout
• replacement of references to ETS 300 102 with EN 300 403
• substitution of non-specific references to basic standards where the latest version is intended

Which standards are used with SIST EN 300 359-1 V1.3.2:2005?

Reference	What it contributes
ITU-T Recommendation E.164	International public telecommunication numbering plan used for ISDN numbers
ITU-T Recommendation I.112	ISDN vocabulary
CCITT Recommendation I.130	Method for characterizing telecommunication services and network capabilities
ITU-T Recommendation I.210	Principles of telecommunication services and their description
ITU-T Recommendation I.221	Common specific characteristics of services
ITU-T Recommendation I.411	ISDN user-network interface reference configurations
CCITT Recommendation Q.9	Switching and signalling vocabulary
CCITT Recommendation X.208	ASN.1 notation used for the CCBS operation and error definitions
CCITT Recommendation X.219	Remote operations model, notation and service definition
ITU-T Recommendation Z.100	SDL used for the dynamic description
EN 300 403-1	Circuit-mode basic call control protocol for DSS1
ETS 300 403-2	SDL diagrams for basic call control
EN 300 195-1	Supplementary service interactions
EN 300 196-1	Generic functional protocol for supplementary services, including components and status request procedures
EN 300 267-1	Telephony 7 kHz and videotelephony teleservices, including fallback behavior
ETS 300 358	Functional capabilities and information flows for CCBS
ETS 300 357	Service description for CCBS

What does the SIST EN 300 359-1 V1.3.2:2005 document contain?

SIST EN 300 359-1 V1.3.2:2005 contains ASN.1 definitions for CCBS operations, errors and object identifiers, plus the private-network ASN.1 set used for T-reference-point interworking. It also contains state definitions for user A, network A and network B, which show how the service moves from idle to requested, activated, suspended or call-initiation states.

The document includes detailed signalling procedures for activation, deactivation, interrogation, recall, CCBS call setup, queue B processing, call information retention and interactions with other supplementary services. It also contains SDL diagrams that show the message flow between user, network A, network B and private-network entities.

Annex A provides signalling flow examples for specific recall, global recall, deactivation and private ISDN cases. Annex B sets the rule set for status request procedures, Annex C assigns object identifier values, and Annex D records the changes from earlier editions.

SLOVENSKI STANDARD
01-april-2005
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Integrated Services Digital Network (ISDN); Completion of Calls to Busy Subscriber
(CCBS) supplementary service; Digital Subscriber Signalling System No. one (DSS1)
protocol; Part 1: Protocol specification
Ta slovenski standard je istoveten z: EN 300 359-1 Version 1.3.2
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.

European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
Completion of Calls to Busy Subscriber (CCBS)
supplementary service;
Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification

2 ETSI EN 300 359-1 V1.3.2 (2000-06)
Reference
REN/SPS-05201-1
Keywords
CCBS, DSS1, ISDN, protocol, supplementary
services
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ETSI
3 ETSI EN 300 359-1 V1.3.2 (2000-06)
Contents
Intellectual Property Rights.6
Foreword .6
1 Scope.8
2 References.8
3 Definitions.9
4 Abbreviations .10
5 Description .11
6 Operational requirements.11
6.1 Provision and withdrawal .11
6.2 Requirements on the network A side.11
6.3 Requirements on the network B side .12
7 Coding requirements .12
8 State definitions.15
8.1 User A states.15
8.2 User B states.15
8.3 Network A states .16
8.4 Network B states .16
9 Signalling procedures at the coincident S and T reference point .16
9.1 Activation .16
9.1.1 Normal operation.16
9.1.2 Exceptional procedures.17
9.2 User initiated deactivation procedure.19
9.2.1 Normal operation.19
9.2.2 Exceptional procedures.19
9.3 Interrogation.19
9.3.1 General interrogation .19
9.3.1.1 Normal operation .19
9.3.1.2 Exceptional procedures .20
9.3.2 Specific interrogation.20
9.3.2.1 Normal operation .20
9.3.2.2 Exceptional procedures .20
9.4 Invocation and operation.21
9.4.1 Recall indication .21
9.4.1.1 Normal operation .21
9.4.1.2 Exceptional procedures .21
9.4.2 CCBS call request.22
9.4.2.1 Normal operation .22
9.4.2.2 Exceptional procedures .22
9.4.3 CCBS call establishment.23
9.4.3.1 Normal operation .23
9.4.3.2 Exceptional procedures .23
9.4.4 Network initiated deactivation procedures.24
9.4.4.1 Normal operation .24
9.4.4.2 Exceptional procedures .24
9.4.5 B free but A busy procedure .24
9.4.5.1 Normal operation .24
9.4.5.2 Exceptional procedures .25
9.4.6 User A monitoring procedure .25
9.4.6.1 Normal operation .25
9.4.6.2 Exceptional procedures .25
ETSI
4 ETSI EN 300 359-1 V1.3.2 (2000-06)
9.5 Procedures at network B.25
9.5.1 Determination that CCBS is available .25
9.5.1.1 Normal operation .25
9.5.1.2 Exceptional procedures .26
9.5.2 Acceptance of a CCBS request .26
9.5.2.1 Normal operation .26
9.5.2.2 Exceptional procedures .26
9.5.3 Queue B processing .26
9.5.3.1 Normal operation .26
9.5.3.2 Exceptional procedures .27
9.5.4 Determination of user B free.27
9.5.4.1 Normal operation .27
9.5.4.2 Exceptional procedures .28
9.5.5 CCBS call .28
9.5.5.1 Normal operation .28
9.5.5.2 Exceptional procedures .29
9.6 Call information retention .29
9.6.1 Normal operation.29
9.6.2 Exceptional procedures.30
9.7 Basic call information and compatibility checking at user A .30
9.7.1 Normal operation.30
9.7.2 Exceptional procedures.30
10 Procedures for interworking with private ISDNs.31
10.1 Procedures for the originating T reference point.31
10.1.1 CCBS available indication.31
10.1.1.1 Normal operation .31
10.1.1.2 Exceptional procedures .31
10.1.2 CCBS supplementary service request .31
10.1.2.1 Normal operation .31
10.1.2.2 Exceptional procedures .32
10.1.3 User B free indication.32
10.1.3.1 Normal operation .32
10.1.3.2 Exceptional procedures .32
10.1.4 Suspend request .33
10.1.4.1 Normal operation .33
10.1.4.2 Exceptional procedures .33
10.1.5 Resume request.33
10.1.5.1 Normal operation .33
10.1.5.2 Exceptional procedures .33
10.1.6 CCBS call establishment.33
10.1.6.1 Normal operation .33
10.1.6.2 Exceptional procedures .33
10.1.7 Deactivation.34
10.1.7.1 Normal operation .34
10.1.7.2 Exceptional procedures .34
10.2 Procedures for the destination T reference point.34
10.2.1 CCBS available indication.34
10.2.1.1 Normal operation .34
10.2.1.2 Exceptional procedures .34
10.2.2 CCBS supplementary service request .35
10.2.2.1 Normal operation .35
10.2.2.2 Exceptional procedures .35
10.2.3 User B free indication.36
10.2.3.1 Normal operation .36
10.2.3.2 Exceptional procedures .36
10.2.4 Suspend request .36
10.2.4.1 Normal operation .36
10.2.4.2 Exceptional procedures .36
10.2.5 Resume request.36
10.2.5.1 Normal operation .36
ETSI
5 ETSI EN 300 359-1 V1.3.2 (2000-06)
10.2.5.2 Exceptional procedures .37
10.2.6 CCBS call establishment.37
10.2.6.1 Normal operation .37
10.2.6.2 Exceptional procedures .37
10.2.7 Deactivation.38
10.2.7.1 Normal operation .38
10.2.7.2 Exceptional procedures .38
11 Interactions with other networks.38
12 Interactions with other supplementary services .38
13 Parameter values (timers).38
14 Dynamic description (SDL diagrams).39
Annex A (informative): CCBS signalling flows .77
Annex B (normative): Provision of status request procedures.85
Annex C (informative): Assignment of object identifier values.86
Annex D (informative): Change record.87
D.1 Changes with respect to the previous EN 300 359-1 V1.2.4 .87
D.2 Changes with respect to the previous ETS 300 359-1 .87
History.88
ETSI
6 ETSI EN 300 359-1 V1.3.2 (2000-06)
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 ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI 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 Services
Protocols for Advanced Networks (SPAN).
The present document is part 1 of a multi-part EN covering the Digital Subscriber Signalling System No. one (DSS1)
protocol specification for the Integrated Services Digital Network (ISDN) Completion of Calls to Busy Subscriber
(CCBS) 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 [3], the following three level structure is used to describe the
supplementary telecommunication services as provided by European public telecommunications operators under the
pan-European ISDN:
- Stage 1: is an overall service description, from the user's standpoint;
- 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 the stage 3 aspects (signalling system protocols and switching functions) to support the
CCBS supplementary service. The stage 1 and stage 2 aspects are detailed in ETS 300 357 [17] and ETS 300 358 [16],
respectively.
ETSI
7 ETSI EN 300 359-1 V1.3.2 (2000-06)
National transposition dates
Date of adoption of this EN: 19 May 2000
Date of latest announcement of this EN (doa): 31 August 2000
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 28 February 2001
Date of withdrawal of any conflicting National Standard (dow): 28 February 2001
ETSI
8 ETSI EN 300 359-1 V1.3.2 (2000-06)
1 Scope
The present document specifies the stage three of the Completion of Calls to Busy Subscriber (CCBS) 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
ITU-T Recommendation I.411 [6]) 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 telecommunication service
(see CCITT Recommendation I.130 [3]).
In addition, the present document specifies the protocol requirements at the T reference point where the service is
provided to the user via an intermediate 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 CCBS supplementary service enables user A, encountering a busy destination B, to have the call completed without
having to make a new call attempt when the busy destination B becomes not busy.
The CCBS supplementary service is applicable to all circuit-switched telecommunication services, except the video
telephony teleservice involving a second connection.
Further parts of EN 300 359 specify the method of testing required to identify conformance to the present document.
The present document is applicable to equipment supporting the CCBS 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 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, 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] ITU-T Recommendation E.164 (1997): "The international public telecommunication numbering
plan".
[2] ITU-T Recommendation I.112 (1993): "Vocabulary of terms for ISDNs".
[3] CCITT Recommendation I.130 (1988): "Method for the characterization of telecommunication
services supported by an ISDN and network capabilities of an ISDN".
[4] ITU-T Recommendation I.210 (1993): "Principles of telecommunication services supported by an
ISDN and the means to describe them".
[5] ITU-T Recommendation I.221 (1993): "Common specific characteristics of services".
[6] ITU-T Recommendation I.411 (1993): "ISDN user-network interfaces - Reference configurations".
[7] CCITT Recommendation Q.9 (1988): "Vocabulary of switching and signalling terms".
[8] CCITT Recommendation X.208 (1988): "Specification of Abstract Syntax Notation One
(ASN.1)".
ETSI
9 ETSI EN 300 359-1 V1.3.2 (2000-06)
[9] CCITT Recommendation X.219 (1988): "Remote operations: Model, notation and service
definition".
[10] ITU-T Recommendation Z.100 (1993): "CCITT Specification and description language (SDL)".
[11] 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]".
[12] ETS 300 403-2: "Integrated Services Digital Network (ISDN); Digital Subscriber Signalling
System No. one (DSS1) protocol; Signalling network layer for circuit-mode basic call control;
Part 2: Specification and Description Language (SDL) diagrams".
[13] EN 300 195-1: "Integrated Services Digital Network (ISDN); Supplementary service interactions;
Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification".
[14] 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".
[15] EN 300 267-1: "Integrated Services Digital Network (ISDN); Telephony 7 kHz and
videotelephony teleservices; Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification".
[16] ETS 300 358: "Integrated Services Digital Network (ISDN); Completion of Calls to Busy
Subscriber (CCBS) supplementary service; Functional capabilities and information flows".
[17] ETS 300 357: "Integrated Services Digital Network (ISDN); Completion of Calls to Busy
Subscriber (CCBS) supplementary service; Service description".
3 Definitions
For the purposes of the present document, the following terms and definitions apply:
busys: see ITU-T Recommendation I.221 [5], subclause 2.1.5.
call: see CCITT Recommendation Q.9 [7], definition 2201.
call information retention: procedure of network A to store the call information of a specific call so that it can be used
for that call.
call state: state as defined in EN 300 403-1 [11], subclause 2.1 for either the user or the network as appropriate. A call
state may exist for each call reference value (and for each additional responding CEI in the incoming call states).
CCBS busy: any one of the following conditions will cause a CCBS busy condition:
- maximum number of calls reached at user A (see ITU-T Recommendation I.221 [5], subclause 2.1.3, item 2);
- no B-channels available at user A;
- CCBS recall pending on user A.
CCBS call: call which is established under the control of the CCBS supplementary service.
CCBS recall: procedure where user A is requested to complete the communication when user B ceases to be busy.
CCBS request retention: if an attempt to establish a CCBS call fails because the destination is busy again, then the
network provider option "CCBS request retention" defines whether the CCBS supplementary service shall continue or
not, i.e. if the "CCBS request retention" is supported, the original CCBS request shall retain its position in the queue B,
and monitoring of user B shall continue. Otherwise the CCBS request will be deactivated.
destination B: entity addressed in the original call.
ETSI
10 ETSI EN 300 359-1 V1.3.2 (2000-06)
existing service: basic telecommunication service associated with speech, 3,1 kHz audio and 64 kbit/s unrestricted
bearer capabilities.
Integrated Services Digital Network (ISDN): see ITU-T Recommendation I.112 [2], definition 308.
invoke component: see EN 300 196-1 [14], subclause 8.2.2.1. Where reference is made to an "xxxx" invoke
component, an invoke component is meant with its operation value set to the value of the operation "xxxx".
ISDN number: number conforming to the numbering plan and structure specified in ITU-T Recommendation E.164 [1].
network: DSS1 protocol entity at the network side of the user-network interface.
network A: network, at the coincident S and T reference point, to which user A is attached.
network B: network, at the coincident S and T reference point, which is identified as destination B.
private network: DSS1 protocol entity at the user side of the user-network interface at the T reference point.
public network: DSS1 protocol entity at the network side of the user-network interface at the T reference point.
queue A: buffer at network A for the control of CCBS requests associated with user A, provided on a per-ISDN number
basis.
queue B: buffer at network B for the control of CCBS requests associated with destination B. Resource is provided in
the buffer for each ISDN number, but the buffer is processed on a per-access basis. The buffer is used to support the
monitoring of user B to become not busy.
reject component: see EN 300 196-1 [14], subclause 8.2.2.4.
return error component: see EN 300 196-1 [14], subclause 8.2.2.3. Where reference is made to an "xxxx" return error
component, a return error component is meant which is related to an "xxxx" invoke component.
return result component: see EN 300 196-1 [14], subclause 8.2.2.2. Where reference is made to an "xxxx" return
result component, a return result component is meant which is related to an "xxxx" invoke component.
service; telecommunication service: see ITU-T Recommendation I.112 [2], definition 201.
supplementary service: see ITU-T Recommendation I.210 [4], subclause 2.4.
user: DSS1 protocol entity at the user side of the user-network interface.
user A: user, at the coincident S and T reference point, who originated the call and to whom the CCBS supplementary
service is provided.
user B: user, at the coincident S and T reference point, which is identified as destination B.
4 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ASN.1 Abstract Syntax Notation One
CCBS Completion of Calls to Busy Subscriber
DCR Dummy Call Reference
DSS1 Digital Subscriber Signalling System No. one
ISDN Integrated Services Digital Network
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11 ETSI EN 300 359-1 V1.3.2 (2000-06)
5 Description
The CCBS supplementary service enables user A, encountering a busy destination B, to have the call completed without
having to make a new call attempt when the destination B becomes not busy.
When user A requests the CCBS supplementary service, the network B will monitor destination B for becoming not
busy.
When the destination B becomes not busy, (i.e. access resources e.g. one B-channel are not busy) then the network will
wait a short time in order to allow the resources to be reused for originating a call. If the resources are not reused within
this time by destination B, then the network B will automatically recall user A.
When user A accepts the CCBS recall, then network A will automatically generate a CCBS call to destination B.
6 Operational requirements
6.1 Provision and withdrawal
CCBS may be provided to subscribers by the service provider on a subscription basis or may be generally available.
Withdrawal may happen on subscriber's request or for administrative reasons.
As a service provider option, the CCBS supplementary service can be offered with a subscription option which shall
apply to the whole access of user A.
Table 1 summarizes the subscription options for the CCBS supplementary service.
Table 1: Subscription option
Subscription option Value Meaning
Recall mode Global recall CCBS recall offered to all compatible terminals.
Specific recall CCBS recall offered to the terminal which has activated the
CCBS supplementary service.
If the subscription option is not offered, one of the two values shall be chosen by the network provider.
Table 2 summarizes the network options which apply to the CCBS supplementary service.
Table 2: Network options
Network option Value Meaning
Check for identical calls Yes The network checks if CCBS is requested for a call identical to
a call for which CCBS is already activated.
No The network does not check if CCBS is requested for a call
identical to a call for which CCBS is already activated.
CCBS request retention Yes User A's CCBS request is continued if user B is busy again.
No User A's CCBS request does not continue if user B is busy
again. User A can activate CCBS again.
6.2 Requirements on the network A side
The network A side shall register whether the CCBS supplementary service specific functions have to be performed in
network A or in an attached private ISDN.
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12 ETSI EN 300 359-1 V1.3.2 (2000-06)
6.3 Requirements on the network B side
The network B side shall register whether the CCBS supplementary service specific functions have to be performed in
the network B or in an attached private ISDN.
7 Coding requirements
Tables 3 and 4 show the definition of the operations and errors required for the CCBS supplementary service using
ASN.1 as defined in CCITT Recommendation X.208 [8] and using the OPERATION and ERROR macro as defined in
figure 4/X.219 of CCITT Recommendation X.219 [9].
The formal definition of the component types to encode these operations is provided in EN 300 196-1 [14], clause D.1.
The inclusion of components in Facility information elements is defined in EN 300 196-1 [14], subclause 11.2.
Table 3: ASN.1 description of CCBS operations and errors used
at the coincident S and T reference point
CCBS-Operations-and-Errors {ccitt identified-organization etsi(0) 359 operations-and-errors(1)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
EXPORTS CallInfoRetain, EraseCallLinkageID,
CCBSRequest, CCBSDeactivate, CCBSInterrogate, CCBSErase,
CCBSRemoteUserFree, CCBSCall, CCBSStatusRequest, CCBSBFree,
CCBSStopAlerting,
InvalidCallLinkageID, InvalidCCBSReference, LongTermDenial, ShortTermDenial,
CCBSIsAlreadyActivated, AlreadyAccepted, OutgoingCCBSQueueFull,
CallFailureReasonNotBusy, NotReadyForCall;
IMPORTS OPERATION, ERROR
FROM Remote-Operation-Notation
{joint-iso-ccitt remote-operations(4) notation(0)}
notSubscribed, supplementaryServiceInteractionNotAllowed
FROM General-Errors
{ccitt identified-organization etsi(0) 196 general-errors(2)}
Address, PartyNumber, PartySubaddress
FROM Addressing-Data-Elements
{ccitt identified-organization etsi(0) 196 addressing-data-elements(6)}
Q931InformationElement
FROM Embedded-Q931-Types
{ccitt identified-organization etsi(0) 196 embedded-q931-types(7)};
CallInfoRetain ::= OPERATION
ARGUMENT callLinkageID CallLinkageID
EraseCallLinkageID ::= OPERATION
ARGUMENT callLinkageID CallLinkageID
CCBSRequest ::= OPERATION
ARGUMENT callLinkageID CallLinkageID
RESULT SEQUENCE {
recallMode RecallMode,
cCBSReference CCBSReference}
ERRORS {notSubscribed, InvalidCallLinkageID, ShortTermDenial,
LongTermDenial, CCBSIsAlreadyActivated,
supplementaryServiceInteractionNotAllowed,
OutgoingCCBSQueueFull, CallFailureReasonNotBusy}
CCBSInterrogate ::= OPERATION
ARGUMENT SEQUENCE {
cCBSReference CCBSReference OPTIONAL,
partyNumberOfA PartyNumber OPTIONAL}
RESULT SEQUENCE {
recallMode RecallMode,
callDetails CallDetails OPTIONAL}
ERRORS {InvalidCCBSReference, notSubscribed}
CCBSDeactivate ::= OPERATION
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13 ETSI EN 300 359-1 V1.3.2 (2000-06)
ARGUMENT cCBSReference CCBSReference
RESULT
ERRORS {InvalidCCBSReference}
CCBSErase ::= OPERATION
ARGUMENT SEQUENCE {
recallMode RecallMode,
cCBSReference CCBSReference,
addressOfB Address,
q931InfoElement Q931InformationElement,
eraseReason CCBSEraseReason}
-- The Bearer capability, High layer compatibility (optional) and Low layer compatibility
-- (optional) information elements shall be embedded in q931InfoElement.
CCBSRemoteUserFree ::= OPERATION
ARGUMENT SEQUENCE {
recallMode RecallMode,
cCBSReference CCBSReference,
addressOfB Address,
q931InfoElement Q931InformationElement}
-- The Bearer capability, High layer compatibility (optional) and Low layer compatibility
-- (optional) information elements shall be embedded in q931InfoElement.
CCBSBFree ::= OPERATION
ARGUMENT SEQUENCE {
recallMode RecallMode,
cCBSReference CCBSReference,
addressOfB Address,
q931InfoElement Q931InformationElement}
-- The Bearer capability, High layer compatibility (optional) and Low layer compatibility
-- (optional) information elements shall be embedded in q931InfoElement.
CCBSCall ::= OPERATION
ARGUMENT cCBSReference CCBSReference
ERRORS {InvalidCCBSReference, AlreadyAccepted,
NotReadyForCall}
CCBSStatusRequest ::= OPERATION
ARGUMENT SEQUENCE {
recallMode RecallMode,
cCBSReference CCBSReference,
q931InfoElement Q931InformationElement}
RESULT BOOLEAN -- free=TRUE, busy=FALSE
-- The Bearer capability, High layer compatibility (optional) and Low layer compatibility
-- (optional) information elements shall be embedded in q931InfoElement.
CCBSStopAlerting ::= OPERATION
ARGUMENT cCBSReference CCBSReference
CallDetails ::= SEQUENCE SIZE(1.5) OF CallInformation
CallInformation ::= SEQUENCE {
addressOfB Address,
q931InfoElement Q931InformationElement,
cCBSReference CCBSReference,
subAddressOfA PartySubaddress OPTIONAL}
-- The Bearer capability, High layer compatibility (optional) and Low layer compatibility
-- (optional) information elements shall be embedded in q931InfoElement.
InvalidCallLinkageID ::= ERROR
InvalidCCBSReference ::= ERROR
LongTermDenial ::= ERROR
ShortTermDenial ::= ERROR
CCBSIsAlreadyActivated ::= ERROR
AlreadyAccepted ::= ERROR
OutgoingCCBSQueueFull ::= ERROR
CallFailureReasonNotBusy ::= ERROR
NotReadyForCall ::= ERROR
CallLinkageID ::= INTEGER (0.127)
CCBSReference ::= INTEGER (0.127)
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14 ETSI EN 300 359-1 V1.3.2 (2000-06)
CCBSEraseReason ::= ENUMERATED {
normal-unspecified (0),
t-CCBS2-timeout (1),
t-CCBS3-timeout (2),
basic-call-failed (3)}
RecallMode ::= ENUMERATED {
globalRecall (0),
specificRecall (1)}
cCBSOID OBJECT IDENTIFIER ::= {ccitt identified-organization etsi(0) 359
operations-and-errors(1)}
callInfoRetain CallInfoRetain ::= globalValue {cCBSOID 1}
cCBSRequest CCBSRequest ::= globalValue {cCBSOID 2}
cCBSDeactivate CCBSDeactivate ::= globalValue {cCBSOID 3}
cCBSInterrogate CCBSInterrogate ::= globalValue {cCBSOID 4}
cCBSErase CCBSErase ::= globalValue {cCBSOID 5}
cCBSRemoteUserFree CCBSRemoteUserFree ::= globalValue {cCBSOID 6}
cCBSCall CCBSCall ::= globalValue {cCBSOID 7}
cCBSStatusRequest CCBSStatusRequest ::= globalValue {cCBSOID 8}
cCBSBFree CCBSBFree ::= globalValue {cCBSOID 9}
eraseCallLinkageID EraseCallLinkageID ::= globalValue {cCBSOID 10}
cCBSStopAlerting CCBSStopAlerting ::= globalValue {cCBSOID 11}
invalidCallLinkageID InvalidCallLinkageID ::= globalValue {cCBSOID 20}
invalidCCBSReference InvalidCCBSReference ::= globalValue {cCBSOID 21}
longTermDenial LongTermDenial ::= globalValue {cCBSOID 22}
shortTermDenial ShortTermDenial ::= globalValue {cCBSOID 23}
cCBSIsAlreadyActivated CCBSIsAlreadyActivated ::= globalValue {cCBSOID 24}
alreadyAccepted AlreadyAccepted ::= globalValue {cCBSOID 25}
outgoingCCBSQueueFull OutgoingCCBSQueueFull ::= globalValue {cCBSOID 26}
callFailureReasonNotBusy CallFailureReasonNotBusy ::= globalValue {cCBSOID 27}
notReadyForCall NotReadyForCall ::= globalValue {cCBSOID 28}
END -
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