SIST EN 300 286-1 V1.2.4:2005

• Abstract:

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

• Status: Published
• Publication Date: 31-Mar-2005
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2005
• Due Date: 01-Apr-2005
• Completion Date: 01-Apr-2005
• Ref Project: ETSI EN 300 286-1 V1.2.4 (1998-06) - Integrated Services Digital Network (ISDN); User-to-User Signalling (UUS) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification

SIST EN 300 286-1 V1.2.4:2005 is the Slovenian adoption of EN 300 286-1 Version 1.2.4 for the Integrated Services Digital Network (ISDN) User-to-User Signalling (UUS) supplementary service. It specifies the Digital Subscriber Signalling System No. one (DSS1) protocol at stage 3, so it defines the signalling procedures, coding and state handling used by the user and the network. The document is intended for implementations at the T reference point or coincident S and T reference point, including private ISDN access.

What does SIST EN 300 286-1 V1.2.4:2005 specify?

SIST EN 300 286-1 V1.2.4:2005 specifies the stage 3 protocol for UUS on the pan-European ISDN. In practice, that means it tells an implementer how user-to-user information is carried, accepted, rejected, cleared and flow-controlled in DSS1 signalling.

The document is structured as a protocol specification with definitions, abbreviations, coding rules, state definitions, signalling procedures, interworking rules, timer values and SDL diagrams. The foreword also places it in a six-part series that includes conformance, user test, and network test material.

Annex	What it covers
Annex A	Informative signalling flows for the main UUS cases
Annex B	Informative diagrammatic descriptions of the coding rules
Annex C	Informative changes relative to the previous ETS 300 286-1
Annex D	Informative bibliography

The scope centers on ISDN operation at the T reference point or coincident S and T reference point, and it also covers the same service when the user is attached through a private ISDN.

What are the key requirements of SIST EN 300 286-1 V1.2.4:2005?

Clause 5 defines UUS as a way to exchange a limited amount of user-generated information transparently over the signalling channel associated with a call. That matters because the network passes the information through without interpreting it, so terminals and networks must preserve the content exactly as carried.

Service model and payload limits

Clause 5 splits UUS into three services. Service 1 carries UUI in call control messages during call setup and clearing, service 2 carries UUI in USER INFORMATION messages during the alerting phase, and service 3 carries UUI in USER INFORMATION messages during the active phase. The clause also says that services can be used individually or in combination, so implementations need to support mixed use on one call where it is configured.

Clause 5 limits the amount of information carried in the User-user information element content to 128 octets per message. A note also records an interim period where some networks may only support 32 octets for service 1, which is important for interoperability with older networks.

Provisioning and network behavior

Clause 6 says UUS is provided only after prior arrangement with the network, while the remote user does not need a subscription. The network may offer service 1 implicit, service 1 implicit plus explicit, service 2, service 3, or combinations of these. For a buyer or integrator, this is the place to check which service options a network profile must support.

Clause 6 also requires the originating and destination network sides to pass UUI in both directions and to check that the service is activated before accepting it. For services 2 and 3, the network controls the flow of UUI received from the local user. That matters because message handling is not just transport - the network also enforces service state and rate limits.

Coding and information elements

Clause 7.1 specifies that UUS uses a Facility information element with invoke, return result, return error and reject components. The ASN.1 definition names the operation UserUserService and the associated service and preferred fields. In practice, this is the encoding an implementation must support when it signals service requests and responses.

Clause 7.3 defines the User-user information element and the More data information element used by the service. Clause 7.3.3 shows the protocol discriminator values for the User-user information element, so equipment has to interpret the payload in the correct context. Clause 7 also ties these encodings to EN 300 196-1 and EN 300 403-1, so the UUS coding is not standalone.

Request, response and clearing rules

Clause 9 is the core signaling section. It distinguishes between required and preferred requests. A required request must cause call rejection if the service cannot be accepted, while a preferred request allows the call to continue without the service.

Clause 9 also requires service 1 to support implicit request, and it lets service 1 be explicitly requested through the Facility information element. Services 2 and 3 are explicitly requested, and multiple UUS services requested during call establishment are handled independently in the same SETUP message. For practical testing, that means the same call can carry separate acceptance or rejection outcomes for different services.

For service 2, clause 9 limits use to a point-to-point arrangement at the called user interface. It also allows at most two USER INFORMATION messages in each direction and says that sending or receiving USER INFORMATION does not change the call state. The network may optionally transfer USER INFORMATION after answer.

For service 3, clause 9 allows use only in the active phase and requires independent flow control in each direction. The document defines timers T1-UUS3, T2-UUS3 and T3-UUS3 as 10 s each, and the SDL diagrams show what happens on request collisions, timeouts and repeated USER INFORMATION messages. That matters for implementations that need to avoid overrunning the peer with UUS traffic.

Interworking and other cases

Clause 10 gives the special rules for private ISDNs, including different handling of rejection indications and flow control. Clause 11 covers interworking with a network that supports only 35 octets for the User-user information element, and with non-ISDN destinations through progress indicators in the basic call. Clause 12 points to EN 300 195-1 for interactions with other supplementary services.

What terms does SIST EN 300 286-1 V1.2.4:2005 define?

• Call control message - A message that changes call state on send or receipt, such as SETUP, ALERTING, CONNECT, DISCONNECT or RELEASE.
• Explicit request - A UUS request signalled with a Facility information element in SETUP or FACILITY, which requires an explicit accept or reject.
• Implicit request - A UUS request signalled by including a User-user information element in SETUP.
• Point-to-point arrangement - The called user interface accepts a response from only one user.
• Point-to-multipoint arrangement - The called user interface can accept responses from more than one terminal, which creates contention handling cases.
• Preferred request - A request where call setup continues even if the UUS service cannot be accepted.
• Required request - A request where call setup is rejected if the UUS service cannot be accepted.
• User-To-User Information (UUI) - The user-generated information transferred between users by the UUS supplementary service.

Who uses SIST EN 300 286-1 V1.2.4:2005?

SIST EN 300 286-1 V1.2.4:2005 is used by ISDN equipment makers, network operators, terminal vendors, and conformance test engineers. They use it to implement UUS signalling in terminals, exchanges and gateways, and to check how calls behave when UUI is requested, accepted, rejected or cleared.

It is also relevant to quality managers and procurement teams who need to verify that an ISDN product supports the right UUS service modes, the right call phases and the right interworking behavior. For test labs, the SDL diagrams and signaling flows provide the basis for protocol validation.

What changed in SIST EN 300 286-1 V1.2.4:2005 from the previous edition?

Annex C states three changes relative to the previous ETS 300 286-1: conversion to EN layout, replacement of references to ETS 300 102 with EN 300 403, and substitution of non-specific references where the intent is to use the latest version. The foreword also says that this version updates the references to the basic call specifications.

Which standards are used with SIST EN 300 286-1 V1.2.4:2005?

• ITU-T Recommendation I.112 - Supplies the ISDN vocabulary used for core terms.
• CCITT Recommendation I.130 - Provides the three-stage method for describing telecommunication services.
• ITU-T Recommendation I.210 - Gives the general principles for telecommunication services supported by ISDN.
• ITU-T Recommendation I.411 - Defines the reference configurations for the user-network interface.
• CCITT Recommendation X.208 - Provides ASN.1, used for the UUS operation and error definitions.
• CCITT Recommendation X.219 - Provides the remote operations model and notation used for Facility components.
• CCITT Recommendation Z.100 - Provides the SDL notation used in the dynamic descriptions.
• EN 300 403-1 - Supplies the basic call control protocol used for message structure, call states and error handling.
• EN 300 403-2 - Supplies the SDL diagrams for basic call control symbol direction and call context.
• EN 300 195-1 - Defines interactions between UUS and other supplementary services.
• EN 300 196-1 - Defines the generic supplementary-service protocol, including Facility information element handling.
• CCITT Recommendation X.244 - Supports one of the protocol discriminator values for User-user information.
• CCITT Recommendation X.25 - Supports the packet-mode related discriminator values cited in the User-user information element.
• Part 2 of EN 300 286 - Covers the Protocol Implementation Conformance Statement proforma.
• Part 3 of EN 300 286 - Covers the user Test Suite Structure and Test Purposes.
• Part 4 of EN 300 286 - Covers the user Abstract Test Suite and partial PIXIT proforma.
• Part 5 of EN 300 286 - Covers the network Test Suite Structure and Test Purposes.
• Part 6 of EN 300 286 - Covers the network Abstract Test Suite and partial PIXIT proforma.

What does the SIST EN 300 286-1 V1.2.4:2005 document contain?

Clause 7 contains the coding rules, including the ASN.1 operation and error definitions, the Facility information element handling, and the User-user information element coding. Clause 7 also identifies the message types and information elements used by UUS.

Clause 9 and Annex A provide the signaling procedures and arrow diagrams for the main cases, including implicit and explicit service 1, service 2 in the alerting phase, service 3 in call establishment and active state, premature clearing, point-to-point and point-to-multipoint arrangements, and service 3 flow control. Clause 14 gives SDL process models for the user side and network side of services 1, 2 and 3.

Annex B gives diagrammatic examples of the coding structures for the UUS request invoke component, return result component and return error component. Together, these annexes support implementation, interoperability testing and protocol conformance work.

SLOVENSKI STANDARD
01-april-2005
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Integrated Services Digital Network (ISDN); User-to-User Signalling (UUS)
supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification
Ta slovenski standard je istoveten z: EN 300 286-1 Version 1.2.4
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 300 286-1 V1.2.4 (1998-06)
European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
User-to-User Signalling (UUS) supplementary service;
Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification

2 EN 300 286-1 V1.2.4 (1998-06)
Reference
REN/SPS-05145-T-1 (2nc90iqo.PDF)
Keywords
ISDN, UUS, DSS1, supplementary service
ETSI
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Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1998.
All rights reserved.
ETSI
3 EN 300 286-1 V1.2.4 (1998-06)
Contents
Intellectual Property Rights. 5
Foreword. 5
1 Scope . 7
2 Normative references. 7
3 Definitions. 8
4 Abbreviations.9
5 Description . 10
5.1 Service 1.10
5.2 Service 2.10
5.3 Service 3.11
6 Operational requirements . 11
6.1 Provision and withdrawal.11
6.2 Requirements on the originating network side.11
6.3 Requirements on the destination network side .11
7 Coding requirements. 11
7.1 Coding of the Facility information element component .11
7.2 Definition of messages.12
7.2.1 CONGESTION CONTROL .12
7.2.2 USER INFORMATION.13
7.3 Definition of information elements.13
7.3.1 Congestion level.13
7.3.2 More data .13
7.3.3 User-user.14
8 State definitions. 15
9 Signalling procedures at the coincident S and T reference point . 16
9.1 Service 1.16
9.1.1 Activation, deactivation and registration.16
9.1.1.1 Service 1 - implicitly requested .16
9.1.1.1.1 Normal operation.16
9.1.1.1.2 Exceptional procedures.17
9.1.1.2 Service 1 - explicitly requested.17
9.1.1.2.1 Normal operation.17
9.1.1.2.2 Exceptional procedures.18
9.1.2 Invocation.19
9.1.2.1 Service 1 invocation during call establishment .19
9.1.2.1.1 Normal operation.19
9.1.2.1.2 Exceptional procedures.19
9.1.2.2 Service 1 invocation during call clearing.20
9.1.2.2.1 Normal operation.20
9.1.2.2.2 Exceptional procedures.21
9.2 Service 2.21
9.2.1 Activation, deactivation and registration.21
9.2.1.1 Normal operation.21
9.2.1.2 Exceptional procedures .21
9.2.2 Invocation.23
9.2.2.1 Normal operation.23
9.2.2.2 Exceptional procedures .24
9.3 Service 3.25
9.3.1 Activation, deactivation and registration.25
9.3.1.1 Service 3 request during call establishment.25
9.3.1.1.1 Normal operation.25
ETSI
4 EN 300 286-1 V1.2.4 (1998-06)
9.3.1.1.2 Exceptional procedures.25
9.3.1.2 Service 3 request during the Active (N10, U10) call state .27
9.3.1.2.1 Normal operation.27
9.3.1.2.2 Exceptional procedures.27
9.3.2 Invocation.28
9.3.2.1 Normal operation.28
9.3.2.2 Exceptional procedures .28
9.3.3 Flow control.29
9.3.3.1 Normal operation.29
9.3.3.2 Exceptional procedures .29
10 Procedures for interworking with private ISDNs . 29
11 Interaction with other networks . 30
11.1 Interworking with an ISDN network supporting only a maximum User-user information element length of
35 octets.30
11.2 Interaction with non-ISDN .30
12 Interaction with other supplementary services. 30
13 Parameter values (timers). 30
14 Dynamic description (SDL diagrams). 30
14.1 Service 1.32
14.1.1 User.32
14.1.2 Network.36
14.2 Service 2.42
14.2.1 User.42
14.2.2 Network.45
14.3 Service 3.51
14.3.1 User.51
14.3.2 Network.56
Annex A (informative): Signalling flows . 63
A.1 Service 1, implicit request, point-to-multipoint. 64
A.2 Service 1, implicit request, point-to-point . 67
A.3 Service 1, explicit request, point-to-multipoint. 69
A.4 Service 1, explicit request, point-to-point . 73
A.5 Service 2 . 75
A.6 Service 3, request during call establishment, point-to-multipoint . 77
A.7 Service 3, request during the Active (N10, U10) call state. 78
A.8 Service 3, flow control. 79
Annex B (informative): Diagrammatic description of coding requirements . 80
B.1 UUS request invoke component (typical example) . 80
B.2 UUS return result component (typical example) . 81
B.3 UUS return error component (typical example) . 81
Annex C (informative): Changes with respect to the previous ETS 300 286-1 . 82
Annex D (informative): Bibliography. 83
History. 84
ETSI
5 EN 300 286-1 V1.2.4 (1998-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in
SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.fr/ipr or http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can
be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server) which
are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Signalling
Protocols and Switching (SPS).
The present document is part 1 of a multi-part standard covering the Digital Subscriber Signalling System No. one (DSS1)
protocol specification for the Integrated Services Digital Network (ISDN) User-to-User Signalling (UUS) supplementary
service, as described below:
Part 1: "Protocol specification";
Part 2: "Protocol Implementation Conformance Statement (PICS) proforma specification";
Part 3: "Test Suite Structure and Test Purposes (TSS&TP) specification for the user";
Part 4: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the user";
Part 5: "Test Suite Structure and Test Purposes (TSS&TP) specification for the network";
Part 6: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the network".
In accordance with CCITT Recommendation I.130, the following three level structure is used to describe the
supplementary telecommunication services as provided by European public telecommunications operators under the pan-
European 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) needed to support
the UUS supplementary service. The stage 1 and stage 2 aspects are detailed in ETS 300 284 and ETR 285, respectively.
The present version updates the references to the basic call specifications.
ETSI
6 EN 300 286-1 V1.2.4 (1998-06)
National transposition dates
Date of adoption of this EN: 19 June 1998
Date of latest announcement of this EN (doa): 30 September 1998
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 March 1999
Date of withdrawal of any conflicting National Standard (dow): 31 March 1999
ETSI
7 EN 300 286-1 V1.2.4 (1998-06)
1 Scope
This first part of EN 300 286 specifies the stage three of the User-to-User Signalling (UUS) 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 [4]) 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 [2]).
In addition the present document specifies the protocol requirements at the T reference point where the service is
provided to the user via a private ISDN.
The present document does not specify the additional protocol requirements where the service is provided to the user via
a telecommunication network that is not an ISDN.
The UUS supplementary service enables a user to send/receive a limited amount of information to/from another user over
the signalling channel in association with a call to the other user.
The UUS supplementary service is applicable to all circuit-switched telecommunication services.
Further parts of EN 300 286 specify the method of testing required to identify conformance to the present document.
The present document is applicable to equipment supporting the UUS supplementary service to be attached at either side
of a T reference point or coincident S and T reference points when used as an access to the public ISDN.
2 Normative references
References may be made to:
a) specific versions of publications (identified by date of publication, edition number, version number, etc.), in which
case, subsequent revisions to the referenced document do not apply; or
b) all versions up to and including the identified version (identified by "up to and including" before the version
identity); or
c) all versions subsequent to and including the identified version (identified by "onwards" following the version
identity); or
d) publications without mention of a specific version, in which case the latest version applies.
A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] ITU-T Recommendation I.112: "Vocabulary of terms for ISDNs".
[2] CCITT Recommendation I.130 (1988): "Method for the characterisation of telecommunication
services supported by an ISDN and network capabilities of an ISDN".
[3] ITU-T Recommendation I.210: "Principles of telecommunication services supported by an ISDN
and the means to describe them".
[4] ITU-T Recommendation I.411 (1993): "ISDN user-network interfaces - Reference configurations".
[5] CCITT Recommendation X.25 (1988): "Interface between Data Terminal Equipment (DTE) and
Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected
to public data networks by dedicated circuit".
[6] CCITT Recommendation X.208 (1988): "Specification of Abstract Syntax Notation One (ASN.1)".
[7] CCITT Recommendation X.219 (1988): "Remote Operations: Model, Notation and Service
definitions".
[8] CCITT Recommendation X.244 (1988): "Procedure for exchange of protocol identification during
virtual call establishment on packet switched public data networks".
ETSI
8 EN 300 286-1 V1.2.4 (1998-06)
[9] CCITT Recommendation Z.100 (1988): "Specification and description language (SDL)".
[10] 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]".
[11] EN 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".
[12] EN 300 195-1: "Integrated Services Digital Network (ISDN); Supplementary service interactions;
Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification".
[13] 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".
3 Definitions
For the purposes of the present document, the following definitions apply:
call control message: A message as defined in EN 300 403-1 [10], subclause 3.1, which on sending or receipt causes a
change of the call state at either the network or the user. Call control messages also include the PROGRESS message but
not the INFORMATION message.
NOTE: For the purposes of other standards, the information message may be considered as a call control message.
called network: The network to which the called user is attached.
called user: A user that receives a call request which may include a request of the UUS supplementary service.
calling network: The network to which the calling user is attached.
calling user: A user that initiates a call and may include a request of the UUS supplementary service in the call request.
contention: Contention exists when the called user has a point-to-multipoint arrangement and multiple responses to an
incoming call are sent to the network. These responses may carry different information related to the UUS supplementary
service.
explicit request: An explicit request of a UUS supplementary service is one where the request is explicitly identified by
including a Facility information element with an appropriate component in either the SETUP or FACILITY message sent
by the served user. The explicit request requires an explicit response (acceptance or rejection).
explicit service 1: Service 1 explicitly requested.
implicit request: An implicit request of a UUS supplementary service is one where the request is implicitly identified by
including a User-user information element in the SETUP message sent by the served user.
implicit service 1: Service 1 implicitly requested.
Integrated Services Digital Network (ISDN): See ITU-T Recommendation I.112 [1], definition 308.
invoke component: See EN 300 196-1 [13], 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".
network: The DSS1 protocol entity at the network side of the user-network interface.
point-to-multipoint arrangement: In the context of the present document, a point-to-multipoint arrangement exists at the
called user's interface, if the network has the knowledge that the point-to-multipoint layer 3 procedures shall be applied at
the called user's interface. Consequently, responses from more than one terminal are accepted in case of an incoming call.
point-to-point arrangement: In the context of this standard, a point-to-point arrangement exists at the called user's
interface, if the network has the knowledge that the point-to-point layer 3 procedures shall be applied at the called user's
interface. Consequently, a response from only one user is accepted in case of an incoming call.
ETSI
9 EN 300 286-1 V1.2.4 (1998-06)
preferred request: A preferred request of a UUS supplementary service is one where the call setup shall continue even if
the request for the UUS supplementary service cannot be accepted.
premature clearing: The calling or called user initiates call clearing before the call has reached the Active (N10, U10)
call state.
receiving network: The network to which the receiving user is attached.
receiving user: The user receiving USER INFORMATION messages as part of service 2 or 3.
reject component: See EN 300 196-1 [13], subclause 8.2.2.4.
remote network: The network to which the remote user is attached.
remote user: The user who receives a request for service 3 in the Active (U10) call state.
required request: A required request of a UUS supplementary service is one where the call setup shall be rejected if the
request for the UUS supplementary service cannot be accepted.
requesting network: The network to which the requesting user is attached.
requesting user: The user who sends a request for the UUS supplementary service 3 in the Active (U10) call state.
return error component: See EN 300 196-1 [13], 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 [13], 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".
sending network: The network to which the sending user is attached.
sending user: The user sending USER INFORMATION messages as part of service 2 or 3.
served user: The user who is the requester of the UUS supplementary service. For service 1 and service 2, the served
user is always at the originating side. For service 3, the served user may be at the originating or the destination side.
service; telecommunication service: See ITU-T Recommendation I.112 [1], definition 201.
service 1: A form of the UUS supplementary service where UUI can be sent and received as part of call control messages
for originating and terminating calls.
service 2: A form of the UUS supplementary service where UUI can be sent and received independently of call control
messages in the alerting phase of a call.
service 3: A form of the UUS supplementary service where UUI can be sent and received independently of call control
messages once the connection has been established.
supplementary service: See ITU-T Recommendation I.210 [3], subclause 2.4.
user: The DSS1 protocol entity at the user side of the user-network interface.
user information: The information contained in octet 4 and onwards of the User-user information element.
User-To-User Information (UUI): The information transferred between users in the User-user information element by
the UUS supplementary service.
4 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ASN.1 Abstract Syntax Notation one
DSS1 Digital Subscriber Signalling System No. one
ISDN Integrated Services Digital Network
SDL Specification and Description Language
ETSI
10 EN 300 286-1 V1.2.4 (1998-06)
UUI User-to-User Information
UUS User-to-User Signalling
5 Description
The UUS supplementary service enables a user to send/receive a limited amount of user-generated information (i.e. the
User-user information element and, in addition for services 2 and 3, the More data information element) to/from another
user. This information shall be passed transparently (i.e. without modification of content) through the network over the
signalling channel in association with the call. The network shall not interpret or act upon this information.
The information is contained in either call control messages or in separate USER INFORMATION messages. The amount
of information (i.e. the User-user information element content) is limited to 128 octets per message.
NOTE: During an interim period of time, some networks may support only the transfer of 32 octets of UUI per
message on service 1.
Within the UUS supplementary service three different services may be provided by the network:
- service 1: exchange of user-to-user information between users during the setup and clearing phases of a call,
within call control messages;
- service 2: exchange of user-to-user information between users in the alerting phase of a call, within USER
INFORMATION messages;
- service 3: exchange of user-to-user information between users in the active phase of a call, within USER
INFORMATION messages.
Services 1, 2 and 3 may be used individually or in any combination in association with a single call.
Services 1, 2 and 3 are requested by the calling user. As a network option, service 3 can be requested by the called user
during the active phase of a call.
Service 1 may be requested either implicitly or explicitly. Services 2 and 3 are always requested explicitly. Networks
supporting the UUS supplementary service 1 shall support at least the service 1 implicitly requested.
In case of explicit request, the calling user shall, at call setup, specify whether the requested UUS supplementary
service(s) is(are) required or preferred for the call (required request/preferred request).
The UUS supplementary service can be used in conjunction with the videotelephony teleservice. For videotelephony calls
involving two connections, the procedures in the present document for activation and invocation (including flow control)
apply independently for each connection.
5.1 Service 1
For this service, both users may exchange UUI during the setup and the clearing phases of a call by including UUI in basic
call control messages.
In addition, if a point-to-multipoint arrangement exists at the called user's interface, the following applies:
- in the network-to-called-user direction: in case of premature clearing by the calling user, UUI shall, if provided in
the clearing request, be delivered to all terminals having confirmed the call at this time;
- in the called user-to-network direction: if UUI is sent in the alerting indication, it is up to the called user to avoid
contention. In case the call is cleared by the called user before the active phase by means of multiple clearing
messages, the UUI (if any) received together with the selected rejection cause shall be sent to the calling user.
5.2 Service 2
For this service, both users may send UUI after the alerting indication has been sent/received and until the connect
indication has been sent/received. As a network option, the network can deliver the UUI to the called user after the
connection has been established.
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11 EN 300 286-1 V1.2.4 (1998-06)
The UUI is sent in USER INFORMATION messages and is limited to two messages in each direction.
Service 2 is only applicable if a point-to-point arrangement exists at the called user's interface.
5.3 Service 3
For this service, both users may send UUI in the active phase of a call using USER INFORMATION messages.
The network shall provide flow control limiting the number of messages exchanged in a certain period of time. The flow
control of each direction shall be operated independently.
6 Operational requirements
6.1 Provision and withdrawal
The UUS supplementary service shall be provided to the user after prior arrangement with the network. No subscription is
required for the remote user.
As a network option, one or any combination of the following possibilities can be provided separately or globally:
- service 1 implicit, or service 1 implicit together with service 1 explicit;
- service 2;
- service 3.
The UUS supplementary service shall be withdrawn by the network upon request of the subscriber or for network reasons.
As a network option, withdrawal can be done separately per service provided, or globally for all services provided to the
served user.
6.2 Requirements on the originating network side
The originating network shall be able to receive UUI from the user and convey it towards the destination network; and to
receive UUI from the destination network and convey it to the user.
For services 2 and 3, the network shall control the flow of UUI received from the local user.
The originating network shall check that the service has been activated; otherwise appropriate error handling shall take
place.
6.3 Requirements on the destination network side
For the destination network the same requirements apply as for the originating network side.
7 Coding requirements
7.1 Coding of the Facility information element component
Table 1 shows the definition of the operation and errors required for the UUS supplementary service using ASN.1 as
defined in CCITT Recommendation X.208 [6] and using the OPERATION and ERROR macro as defined in figure
4/X.219 of CCITT Recommendation X.219 [7].
The formal definition of the component types to encode these operations and errors is provided in EN 300 196-1 [13],
annex D, subclause D.1.
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12 EN 300 286-1 V1.2.4 (1998-06)
The inclusion of components in Facility information elements is defined in EN 300 196-1 [13], subclause 11.2.2.1.
All components (invoke, return result, return error and reject) shall be included within a Facility information element.
This Facility information element may be included in any appropriate message as specified in EN 300 196-1 [13],
subclause 8.3.1.1, unless a more restrictive specification is given in clause 9.
Table 1: Operation and error definitions for the UUS supplementary service
User-To-User-Signalling-Operations {ccitt identified-organization etsi(0) 286
operations-and-errors(1)}
DEFINITIONS ::=
BEGIN
EXPORTS         UserUserService, RejectedByUser, RejectedByNetwork, Service, Preferred;
IMPORTS         OPERATION, ERROR
FROM Remote-Operation-Notation
{joint-iso-ccitt remote-operations(4) notation (0)};
UserUserService     ::= OPERATION
ARGUMENT SEQUENCE {
[1] IMPLICIT Service,
[2] IMPLICIT Preferred}
RESULT
ERRORS {rejectedByUser, rejectedByNetwork}
Service         ::= INTEGER {
service1 (1),
service2 (2),
service3 (3)}
(1.3)
Preferred        ::= BOOLEAN   -- True = preferred request
-- False = required request
RejectedByNetwork    ::= ERROR
RejectedByUser     ::= ERROR
userUserService UserUserService   ::= 1
rejectedByNetwork RejectedByNetwork ::= 1
rejectedByUser RejectedByUser    ::= 2
END -- of User-To-User-Signalling-Operations
7.2 Definition of messages
This subclause gives the message structure for the messages used in the UUS supplementary service. The general
definition of the message structure and the key to the interpretation can be found in EN 300 403-1 [10], clause 3.
7.2.1 CONGESTION CONTROL
This message is sent by the network to indicate the establishment or termination of flow control on the transmission of
USER INFORMATION messages. See table 2.
Table 2: Congestion control message content
Message type: CONGESTION CONTROL
Message type value: 01111001
Significance: local
Direction: network-to-user
Information Element Reference Direction Type Length
Protocol discriminator 4.2/EN 300 403-1 n fi uM 1
Call reference 4.3/EN 300 403-1 n fi u M 2 - 3
Message type 4.4/EN 300 403-1 n fi uM 1
Congestion level 7.3.1 n fi uM 1
Cause 4.5/EN 300 403-1 n fi u O (note 1) 2 - 32
Display 4.5/EN 300 403-1 n fi u O (note 2) 2 - 82
NOTE 1: Included if user-to-user information has been discarded as a result of flow control.
NOTE 2: Included if the network provides information that can be presented to the user.
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13 EN 300 286-1 V1.2.4 (1998-06)
7.2.2 USER INFORMATION
This message is sent by the user to the network to transfer information to the remote user. This message is also sent by the
network to the user to deliver information from the other user. See table 3.
Table 3: User information
Message type: USER INFORMATION
Message type value: 0010 0000
Significance: access
Direction: both
Information Element Reference Direction Type Length
Protocol discriminator 4.2/EN 300 403-1 both M 1
Call reference 4.3/EN 300 403-1 both M 2 - 3
Message type 4.4/EN 300 403-1 both M 1
More data 7.3.2 both O (note) 1
User-user 7.3.3 both M 3 - 131
NOTE: Included by the sending user to indicate that another USER INFORMATION message pertaining to the
same message block will follow.
7.3 Definition of information elements
This subclause gives the coding for the information elements used in the UUS supplementary service. The general
definition of the information element structure can be found in EN 300 403-1 [10], clause 4.
7.3.1 Congestion level
The purpose of the Congestion level information element is to describe the congestion status of the call. It is a single octet
information element coded as shown in figure 1 and table 4.
87654321 Octet
Congestion level
1011 Congestion level 1
Information element identifier
Figure 1: Congestion level information element
Table 4: Congestion level information element
Congestion level (octet 1)
Bits
4 3 2 1
0 0 0 0 receiver ready
1 1 1 1 receiver not ready
All other values are reserved.
7.3.2 More data
The More data information element is sent by the user to the network in a USER INFORMATION message, and delivered
by the network to the destination user in the corresponding USER INFORMATION message. The presence of the More
data information element indicates to the destination user that another USER INFORMATION message will follow,
containing information belonging to the same block.
The use of the More data information element is not supervised by the network.
The More data information element is coded as shown in figure 2.
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14 EN 300 286-1 V1.2.4 (1998-06)
87654321 Octet
More data
10100000 1
Information element identifier
Figure 2: More data information element
7.3.3 User-user
The purpose of the User-user information element is to convey information between ISDN users. This information is not
interpreted by the network, but is carried transparently and delivered to the receiving user(s).
The User-user information element is coded as shown in figure 3 and table 5. There are no restrictions on the contents of
the user information field.
In addition to the USER INFORMATION message, the User-user information element can be included in the SETUP,
ALERTING, CONNECT, DISCONNECT, PROGRESS, RELEASE and RELEASE COMPLETE messages.
NOTE 1: On service 1, during an interim period of time, some networks may only support the transfer of 35 octets of
the User-user information element per message.
NOTE 2: The User-user information element is transported transparently by an ISDN between a call originating
entity, e.g. a calling user, and the addressed entity, e.g. a user or a high layer function network node
addressed by the call originating entity.
87654321 Octet
User-user
01111110 1
Information element identifier
Length of user-user contents 2
Protocol discriminator 3
User information 4 etc.
Figure 3: User-user information element
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15 EN 300 286-1 V1.2.4 (1998-06)
Table 5: User-user information element
Protocol discriminator (octet 3)
Bits
8 7 6 5 4 3 2 1
0 0 0 0 0 0 0 0 User-specific protocol (note 1)
0 0 0 0 0 0 0 1 OSI high layer protocol
0 0 0 0 0 0 1 0 CCITT Recommendation X.244 (note 2)
0 0 0 0 0 0 1 1 Reserved for system management convergence function
0 0 0 0 0 1 0 0 IA5 characters (note 4)
0 0 0 0 0 1 1 1 CCITT Recommendation V.120 rate adaption
0 0 0 0 1 0 0 0 CCITT Recommendation Q.931 (I.451) user-network call control messages
0 0 0 1 0 0 0 0 } reserved for other network layer or layer 3 protocols,
through } including CCITT Recommendation X.25
0 0 1 1 1 1 1 1 } (note 3)
0 1 0 0 0 0 0 0 }
through } national use
0 1 0 0 0 1 1 1 }
0 1 0 0 1 0 0 0 }
through } reserved for ETSI
0 1 0 0 1 1 1 1 }
0 1 0 1 0 0 0 0 } reserved for other network layer or layer 3 protocols,
through } including CCITT Recommendation X.25
1 1 1 1 1 1 1 0 } (note 3)
All other values are reserved.
NOTE 1: The user information is structured according to user needs.
NOTE 2: The user information is structured according to CCITT Recommendation X.244 [8] which specifies the
structure of CCITT Recommendation X.25 [5] call user data.
NOTE 3: These values are reserved to discriminate these protocol discriminators from the first octet of a CCITT
Recommendation X.25 [5] packet including a general format identifier.
NOTE 4: The user information consists of IA5 characters.
8 State definitions
The call states associated with basic call control according to EN 300 403-1 [10] shall apply.
The following UUS supplementary service specific states are defined for the user:
- Idle: the service is deactivated;
- Calling User Reques
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