ISO/IEC TR 18057:2004

Information technology — Telecommunications and information exchange between systems — Using ECMA-323 (CSTA XML) in a Voice Browser Environment

ISO/IEC TR 18057:2003 illustrates how ECMA-323 can be used in a Voice Browser environment. These concepts illustrated in this TR can be applied to any Voice Browser environment that provides an XML-based read/write messaging interface (i.e. CSTA Service Boundary) that supports asynchronous events from a CSTA conformant communication platform. SALT enabled browsers that implement a ECMA-323 interface for call control using the SALT smex mechanism is an example of a browser with this capability.

Technologies de l'information — Télécommunications et échange d'information entre systèmes — Utilisation de l'ECMA-323 (CSTA XML) dans un environnement de navigateur de voix

General Information

• Status: Published
• Publication Date: 11-Feb-2004
• ICS: 35.100.10 - Physical layer
• 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: 14-Feb-2026

Overview

ISO/IEC TR 18057:2004 explains how to use ECMA-323 (CSTA XML) for call control in a voice browser environment. Published as a Technical Report (first edition, 2004), it illustrates practical patterns for integrating CSTA XML with voice browsers that expose an XML read/write messaging interface (a CSTA Service Boundary) and support asynchronous events from a CSTA‑conformant communications platform. The report focuses on speech-centric applications where the voice browser handles media and CSTA XML handles telephony control.

Keywords: ISO/IEC TR 18057:2004, ECMA-323, CSTA XML, Voice Browser, call control, XML messaging, telecommunication standards.

Key Topics

• Scope and purpose - Guidance on applying ECMA-323 in voice browser contexts (SALT, CCXML, etc.).
• CSTA concepts - Connection and connection‑state models, state transitions for incoming and outgoing calls.
• CSTA profiles - Defined subsets for voice browser use (Level 1a, Level 1b, Level 2, Basic Telephony) to simplify implementations that only need common call control features.
• Service and event mapping - Examples of service requests/responses and asynchronous events (Delivered, Established, ConnectionCleared, Originated, NetworkReached, etc.).
• Illustrative scenarios - Concrete XML examples for: capability discovery, monitor/start listening, inbound call notification and answer, outbound call initiation, transfer, deflect, single‑step conference, and failure responses.
• Programming examples - Integration samples for SALT/CSTA XML and CCXML/CSTA XML showing typical implementation patterns.
• Normative references - Pointers to ECMA-269 (CSTA services) and ECMA-323 (CSTA XML schemas) as definitive specifications.

Applications

ISO/IEC TR 18057:2004 is practical for:

• Voice browser developers implementing telephony call control via CSTA XML.
• IVR and speech application engineers who need to integrate speech processing with platform call control.
• Contact center and telephony platform integrators exposing a CSTA Service Boundary (XML read/write + asynchronous events).
• SALT‑enabled and CCXML systems that want to use ECMA-323 for call control.
• Developers implementing features like automated answer, call routing, transfer, conferencing, and clear operations using XML messaging.

Who Should Use It

• Software architects and engineers building speech-centric telephony applications.
• Vendors implementing CSTA-compliant communications platforms or middleware.
• Systems integrators connecting voice browsers (SALT/CCXML) to enterprise telephony.

Related Standards

• ECMA-323:2002 - XML Protocol for CSTA (CSTA XML schemas)
• ECMA-269:2002 (ISO/IEC 18051:2003) - CSTA Phase III services
• SALT (Speech Application Language Tags) - voice browser tagset
• CCXML (W3C) - Voice browser call control model

This Technical Report supplies practical, example-driven guidance to accelerate adoption of ECMA-323 for XML-based call control in voice browser environments.

Standards Content (Sample)

TECHNICAL ISO/IEC
REPORT TR
First edition
2004-02-15
Information technology —
Telecommunications and information
exchange between systems — Using
ECMA-323 (CSTA XML) in a Voice
Browser Environment
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Utilisation de l'ECMA-323 (CSTA XML)
dans un environnement de navigateur de voix

Reference number
©
ISO/IEC 2004
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO/IEC 2004
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO/IEC 2004 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope. 1
2 Normative references. 1
3 Brief Overview of ECMA-323. 2
4 Fundamental Concepts. 2
4.1 CSTA Connection. 2
4.2 CSTA Connection State Model . 2
4.3 Connection State Transitions for CSTA Calls. 3
4.3.1 Incoming Call. 3
4.3.2 Outgoing Call. 3
5 CSTA Profiles. 4
5.1 Level 1a Voice Browser Profile. 4
5.1.1 Services. 4
5.1.2 Events. 5
5.2 Level 1b Voice Browser Profile . 5
5.2.1 Services. 5
5.2.2 Events. 5
5.3 Level 2 Voice Browser Profile. 6
5.3.1 Services. 6
5.3.2 Events. 6
5.4 Basic Telephony Profile. 7
5.4.1 Services. 7
5.4.2 Events. 7
5.5 Other Features. 7
6 ECMA-323 Illustrative Examples . 8
6.1 Discovering the Capabilities of a Telephony Platform. 8
6.2 Starting a Monitor (i.e. listening for incoming calls) . 8
6.2.1 Monitor Start – Service Request example . 8
6.2.2 Monitor Start – Service Response example . 9
6.3 Notification of an Inbound Call. 9
6.3.1 Delivered Event example. 9
6.4 Answering an Inbound Call. 10
6.4.1 Answer Call – Service Request example. 10
6.4.2 Answer Call – Service Response example. 11
6.5 Notification of a Connected Call. 11
6.5.1 Established Event example. 11
6.6 Clearing a Connection. 12
6.6.1 Clear Connection– Service Request example. 12
6.6.2 Clear Connection – Service Response example. 12
6.7 Notification of a Cleared Connection. 12
6.7.1 Connection Cleared Event example. 12
6.8 Initiating an Outbound Call . 13
6.8.1 Make Call – Service Request example (refer to Profile). 13
6.8.2 Make Call – Service Response example. 13
6.9 Outbound Call Event Sequence . 14
6.9.1 Originated Event Example. 14
6.9.2 Network Reached Event. 14
6.9.3 Delivered Event. 15
© ISO/IEC 2004 – All rights reserved iii

6.9.4 Established Event.16
6.10 Single Step Transfer.17
6.10.1 Single Step Transfer – Service Request example.17
6.10.2 Single Step Transfer – Service Response example.17
6.11 Notification of a Transferred Connection .17
6.11.1 Transferred Event example.17
6.12 Deflect.18
6.12.1 Deflect – Service Request example.18
6.12.2 Deflect – Service Response example.19
6.13 Notification of a Diverted Connection.19
6.13.1 Diverted Event example.19
6.14 Single Step Conference.20
6.14.1 Single Step Conference – Service Request example .20
6.14.2 Single Step Conference – Service Response example .20
6.15 Notification of an Party Added to a call .21
6.15.1 Conferenced Event example .21
6.16 Failure Response example.22
7 SALT/CSTA XML Programming Example .22
8 CCXML/CSTA XML Programming Example.26
9 CSTA Call Control Features .28
9.1 Services.29
9.2 Events.30

iv © ISO/IEC 2004 – 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.
In exceptional circumstances, the joint technical committee may propose the publication of a Technical Report
of one of the following types:
— type 1, when the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts;
— type 2, when the subject is still under technical development or where for any other reason there is the
future but not immediate possibility of an agreement on an International Standard;
— type 3, when the joint technical committee has collected data of a different kind from that which is
normally published as an International Standard (“state of the art”, for example).
Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether
they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to
be reviewed until the data they provide are considered to be no longer valid or useful.
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 TR 18057, which is a Technical Report of type 3, was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 6, Telecommunications and information exchange
between systems.
ISO/IEC 18057 was prepared by ECMA (as ECMA TR/85) 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.
© ISO/IEC 2004 – All rights reserved v

Introduction
This Technical Report illustrates how CSTA XML (ECMA-323) can be used in a Voice Browser environment.
This TR is part of a suite of ECMA CSTA Phase III Standards and Technical Reports.
All of the Standards and Technical Reports in this Suite are based upon the practical experience of ECMA
member companies and each one represents a pragmatic and widely based consensus.

vi © ISO/IEC 2004 – All rights reserved

TECHNICAL REPORT ISO/IEC TR 18057:2004(E)

Information technology — Telecommunications and information
exchange between systems — Using ECMA-323 (CSTA XML) in
a Voice Browser Environment
1 Scope
Services for Computer Supported Telecommunications Applications are defined by Standard ECMA-269 and
the XML Protocol for those services are defined by Standard ECMA-323.
In many cases, applications require only a small subset of the features standardized in CSTA. In a voice
browser environment, processing speech (not call control) is usually the major focus of the application. For
example, from a CSTA feature perspective, an application may simply need to answer an incoming call and
then later clear it. As these speech-centric applications evolve they can use additional, more advanced,
features standardized by CSTA that are provided by CSTA-conformant communications platforms.
Since ECMA-269 and ECMA-323 are relatively large standards (combined over 1100 pages), it is a challenge
for application developers without prior knowledge of the CSTA standards to know where to find basic
concepts that they need to understand in order to implement basic CSTA features.
This TR illustrates how ECMA-323 can be used in a Voice Browser environment. These concepts illustrated in
this TR can be applied to any Voice Browser environment that provides an XML-based read/write messaging
interface (i.e. CSTA Service Boundary) that supports asynchronous events from a CSTA conformant
communication platform. SALT enabled browsers that implement a ECMA-323 interface for call control using
the SALT smex mechanism is an example of a browser with this capability.
Throughout this TR the term “ECMA-323 enabled voice browser” is used, in a generic sense, to refer to
browser implementation that support a CSTA conformant ECMA-323 interface.
Examples are provided that show how ECMA-323 can be used in several different environments such as
SALT-enabled browsers and CCXML.
2 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.
This TR provides informative examples of how to use ECMA-323 in a Voice Browser environment. The
following ECMA Standards should be used as the definitive references for CSTA:
ECMA-269:2002, Services for Computer Supported Telecommunications Applications (CSTA) Phase III
(ISO/IEC 18051:2003)
ECMA-323:2002, XML Protocol for Computer Supported Telecommunications Applications (CSTA) Phase III
(ISO/IEC 18056:2003)
ECMA CSTA Standards can be used for call control in many different environments. The following references
provide additional information on using the ECMA CSTA Standards in different environments:
SALT Speech language Application Language Tags 1.0 Specification (SALT), SALT Forum, 15 July 2002,
(http://www.saltforum.org).
© ISO/IEC 2004 – All rights reserved 1

CCXML Voice Browser Call Control: CCXML Version 1.0 - W3C Working Draft, W3C, 11 October 2002,
(http://www.w3c.org/TR/ccxml/).
3 Brief Overview of ECMA-323
ECMA-323 consists of a set of XML Schemas based upon the W3C XML Schema Language
Recommendation. The Standard includes schemas for many categories of services defined in ECMA-269
(Services for Computer Supported Telecommunications Applications (CSTA) Phase III).
Call control is just one category of services in ECMA-323. Examples of other categories of services are:
capability exchange (feature discovery) services, call routing services, services to control a device (e.g.
message waiting, writing to display, forwarding settings), and many others.
CSTA provides a protocol independent abstraction layer for applications. It provides a consistent, standards-
st
based messaging interface that can be used with basic 1 party call control based platforms as well as more
rd st
complex 3 party call control (CTI) platforms, or a combination of both (1 party call control with some
rd
additional 3 party call control features).
CSTA modelling and concepts are also compatible with many procedural and object models such as the SALT
CallControl object (chapter 3 of the SALT specification).
4 Fundamental Concepts
This section introduces some informative modelling concepts that are useful to illustrate how ECMA-323
enabled voice browsers can use ECMA-323 messages. The actual ECMA CSTA standards should be used
for the definitive descriptions.
4.1 CSTA Connection
CSTA call control services are applied to CSTA connections. A CSTA connection refers to a relationship
between a call and a telephony endpoint. A CSTA connection is referenced via a CSTA connection identifier.
A CSTA connection identifier consists of a call identifier and a device (endpoint) identifier.
st
In a typical 1 party call control implementation, a voice browser application manipulates only the CSTA
connection directly associated with the voice browser platform. However, other call control implementations
rd
may also provide application control of other endpoints in the call using CSTA services (via 3 party call
control, for example). A device identifier is included in a CSTA connection identifier to allow any endpoint to be
addressed by a voice browser application.
4.2 CSTA Connection State Model
A ECMA-323 enabled voice browser application is informed of connection state transitions (via ECMA-323 call
control events) by placing a monitor on a telephony endpoint via an associated address (e.g. this is how an
application “listens” for incoming calls).
Each CSTA connection in a call is associated with a connection state. CSTA specifies a connection state
model (see ECMA-269, Figure 6-19) that consists of the following connection states:
• Alerting –Indicates an incoming call at an endpoint. Typically the connection may be ringing or it may be in
a pre-alerting (e.g. offered) condition.
• Connected – Indicates that a connection is actively participating in a call. This connection state can be the
result of an incoming or outgoing call.
• Failed – Indicates that call progression has stalled. Typically this could represent that an outgoing call
attempt that encountered a busy endpoint.
2 © ISO/IEC 2004 – All rights reserved

• Held – Indicates that an endpoint is no longer actively participating in a call. For implementations that
support multiple calls per endpoint (i.e. line), a connection could be Held while the line is used to place
another call (consultation transfer on an analog line, for example).
• Initiated – A transient state, usually indicating that the endpoint is initiating a service (e.g. dialtone).
• Null – There is no relationship between the call and the endpoint.
• Queued – Indicates that the call is temporarily suspended at a device (e.g. call has been parked, camped
on).
The CSTA Connection State is provided in ECMA-323 events.
4.3 Connection State Transitions for CSTA Calls
4.3.1 Incoming Call
The following figure illustrates the CSTA events for an incoming call. The connection state of endpoint on the
voice browser platform (called connection) is indicated in parenthesis.
• Delivered Event (Alerting) – Indicates call is alerting. Calls that are “auto-answered” do not sent this event.
A CSTA Answer Call service can be used to answer the call. This results in an Established event.
• Established Event (Connected) – indicates call has been answered. Media path has been established.
The CSTA Clear Connection service can be used to clear the call. A Connection Cleared event is
generated as the result of the Clear Connection service.
• Connection Cleared Event (Null) – indicates connection has cleared. This can be the result of the Clear
Connection service or as the result of any party clearing from the call.

Incoming Call is Call is
Delivered Established Connection
call arrives answered cleared
Event Event Cleared Event
4.3.2 Outgoing Call
The following figure illustrates the CSTA events for an outgoing call. The connection state of the endpoint on
the Voice Browser platform (originating connection) is indicated in parenthesis. This sequence could be the
result of a CSTA Make Call service.
• Originated Event (Connected) – Indicates that the originating connection (an endpoint on the voice
browser platform) is connected.
• Delivered Event (Connected) – Indicates the call is alerting the called party.
• Established Event (Connected) – indicates the called party has answered the call. Media path has been
established.
• Connection Cleared Event (Null) – indicates connection has cleared.

© ISO/IEC 2004 – All rights reserved 3

called party called called
Delivered Established Connection
Originated
is alerted party party
Event Event Event Cleared Event

5 CSTA Profiles
Since many CSTA features are optional, and to enhance application portability across different CSTA
implementations, CSTA standards require a minimal subset of functionality as conformance criteria.
ECMA-269 specifies a set of Profiles. At least one profile is required to be supported. The following profiles
most closely match the call control services and events needed by a Voice Browser application.
th
• Level 1a Voice Browser Profile (added in ECMA-269 5 edition) – provides support for answering an
incoming call, clearing, and moving the call to another endpoint using the Single Step Transfer Call
service. The Get Switching Function Capabilities Service is not required to be supported in this profile.
th
• Level 1b Voice Browser Profile (added in ECMA-269 5 edition) - provides support for answering an
incoming call, clearing, and moving the call to another endpoint using the Deflect Call service. The Get
Switching Function Capabilities Service is not required to be supported in this profile.
th
• Level 2 Voice Browser Profile (added in ECMA-269 5 edition) – provides support for making a call in
addition to the services and events required in either the Level1a Voice Browser Profile of the Level 1b
Voice Browser Profile. The Get Switching Function Capabilities Service is required to be supported in this
profile.
• Basic Telephony Profile –provides support for answering an incoming call, creating an outgoing call, and
clearing the call. The Get Switching Function Capabilities Service is required to be supported in this profile.
NOTE Telephony platforms that interface with networks and/or endpoints that do not expose the underlying
network/device signalling are not expected to provide all of these CSTA events. For example, if the telephony network
does not provide a busy indication, the Failed event is not required.
5.1 Level 1a Voice Browser Profile
5.1.1 Services
The following CSTA services are included in the Level 1a Voice Browser Profile:
• Answer call – Answers an alerting call. In a voice browser, the answering device is an endpoint on the
platform.
• Clear Connection – Clears a connection. In a voice browser environment, the clearing device is an
endpoint on the voice browser platform.
• Single Step Transfer (of a connected call) – Transfers a call to another endpoint. In a voice browser
environment, the transferring device is an endpoint on the voice browser platform and is no longer
involved with the call after the single step transfer service is completed.
• Monitor Start – Establishes a device-type monitor on an endpoint. In a voice browser environment, the
monitored device is an endpoint on the voice browser platform.
• Monitor Stop – Terminates an existing monitor.
4 © ISO/IEC 2004 – All rights reserved

5.1.2 Events
The following CSTA events are included in the Level 1a Voice Browser Profile:
• Connection Cleared – Indicates that an endpoint has disconnected from a call.
• Delivered – Indicates that a call is alerting an endpoint.
• Established – Indicates that an endpoint has answered or been connected to a call.
• Failed – Indicates that a call cannot be completed (e.g. call has encountered a busy endpoint).
• Transferred – Indicates that an existing call has been transferred from an endpoint (on the voice browser
platform) to another endpoint and has been disconnected from the call. This implies that the transferring
device connection state is Null – no Connection Cleared event is generated for the transferring device
after the Transferred event.
5.2 Level 1b Voice Browser Profile
5.2.1 Services
The following CSTA services are included in the Level 1b Voice Browser Profile:
• Answer call – Answers an alerting call. In a voice browser, the answering device is an endpoint on the
platform.
• Clear Connection – Clears a connection. In a voice browser environment, the clearing device is an
endpoint on the voice browser platform.
• Deflect (of a connected call) – Moves a connection away from the deflecting device. In a voice browser
environment, the deflecting device is an endpoint on the voice browser platform and is no longer involved
with the call after the Deflect Call service is completed.
• Monitor Start – Establishes a device-type monitor on an endpoint. In a voice browser environment, the
monitored device is an endpoint on the voice browser platform.
• Monitor Stop – Terminates an existing monitor.
5.2.2 Events
The following CSTA events are included in the Level 1b Voice Browser Profile:
• Connection Cleared – Indicates that an endpoint has disconnected from a call.
• Delivered – Indicates that a call is alerting an endpoint.
• Diverted – Indicates that the endpoint (on the voice browser platform) has redirected a call to another
endpoint and is no longer involved with the call.
• Established – Indicates that an endpoint has answered or been connected to a call.
• Failed – Indicates that a call cannot be completed (e.g. call has encountered a busy endpoint).
© ISO/IEC 2004 – All rights reserved 5

5.3 Level 2 Voice Browser Profile
5.3.1 Services
In this profile, a CSTA implementation is required to provide its capabilities to applications via the ECMA-323
Get Switching Function Capabilities service. The capabilities include the list of ECMA-323 services and events
supported by a telephony platform and the various types of behavior options supported by an implementation
(the profile(s) supported, the types of digits that are allowed in the dialing string for an outbound call, etc.).
Many of the parameters are optional and do not need to be provided in the ECMA-323 message.
The following CSTA services are included in the Level 2 Voice Browser Profile:
• Answer call – Answers an alerting call. In a voice browser, the answering device is an endpoint on the
voice browser platform.
• Clear Connection – Clears a connection. In a voice browser environment, the clearing device is an
endpoint on the voice browser platform.
• Make Call – Establishes a call between two devices. In a voice browser environment, the originating
device is an endpoint on the voice browser platform.
• Monitor Start – Establishes a device-type monitor on an endpoint. In a voice browser environment, the
monitored device is an endpoint on the voice browser platform.
• Monitor Stop – Terminates an existing monitor.
In addition, at least one of the following services must be supported in order to move a connected call away
from an endpoint:
• Single Step Transfer (of a connected call) – Transfers a call to another endpoint. In a voice browser
environment, the transferring device is an endpoint on the voice browser platform and is no longer
involved with the call after the single step transfer service is completed.
• Deflect (of a connected call) – Moves a connection away from the deflecting device. In a voice browser
environment, the deflecting device is an endpoint on the voice browser platform and is no longer involved
with the call after the Deflect Call service is completed.
5.3.2 Events
The following CSTA events are included in the Level 2 Voice Browser Profile:
• Connection Cleared – Indicates that an endpoint has disconnected from a call.
• Delivered – Indicates that a call is alerting an endpoint.
• Established – Indicates that an endpoint has answered or been connected to a call.
• Failed – Indicates that a call cannot be completed (e.g. call has encountered a busy endpoint).
• Network Reached – For an outbound call, indicates that the call has been connected to an external
network via a Network Interface Device.
• Originated – For an outbound call, indicates that the originating endpoint (on the voice browser platform)
is connected to the call.
In addition:
• Diverted (if the Deflect Service was used to move a connected call).
• Transferred (if the Single Step Transfer Service was used to move a connected call)
6 © ISO/IEC 2004 – All rights reserved

5.4 Basic Telephony Profile
5.4.1 Services
In this profile, the CSTA implementation is required to provide its capabilities to applications via the
ECMA-323 Get Switching Function Capabilities service. The capabilities include the list of ECMA-323 services
and events supported by a telephony platform and the various types of behavior options supported by an
implementation (the profile(s) supported, the types of digits that are allowed in the dialing string for an
outbound call, etc.). Many of the parameters are optional and do not need to be provided in the ECMA-323
message.
The following CSTA services are included in the Basic Telephony Profile:
• Answer call – Answers an alerting call. In a voice browser, the answering device is an endpoint on the
platform.
• Clear Connection – Clears a connection. In a voice browser environment, the clearing device is an
endpoint on the voice browser platform.
• Make Call – Establishes a call between two devices. In a voice browser environment, the originating
device is an endpoint on the voice browser platform.
• Monitor Start – Establishes a monitor on an endpoint. In a voice browser environment, the monitored
device is an endpoint on the voice browser platform.
• Monitor Stop – Terminates an existing monitor.
5.4.2 Events
The following CSTA events are included in the Basic Telephony Profile:
• Connection Cleared – Indicates that an endpoint has disconnected from a call.
• Delivered – Indicates that a call is alerting an endpoint.
• Established – Indicates that an endpoint has answered or been connected to a call.
• Failed – Indicates that a call cannot be completed (e.g. call has encountered a busy endpoint).
• Network Reached – For an outbound call, indicates that the call has been connected to an external
network via a Network Interface Device.
• Originated – For an outbound call, indicates that the originating endpoint (on the voice browser platform)
is connected to the call.
• Service Initiated – Indicates that the endpoint (on the voice browser platform) is requesting service (i.e.
dialtone). Some endpoints bypass this state and are not expected to provide this event (e.g. endpoints
that do not provide dialtone).
5.5 Other Features
The services defined in these profiles are a very small subset of the call control features standardized in
CSTA. A telephony platform may provide any number of additional ECMA-323 services and may even provide
features that have not been standardized in ECMA-323 by using the ECMA-323 extension mechanism.
© ISO/IEC 2004 – All rights reserved 7

The following ECMA-323 services and events may also be very useful for voice browser applications:
• Single Step Conference service – This services adds another device into an existing call. Unlike the
Single Step Transfer service, no devices are dropped from the call as a result of this service.
• Conferenced event – Indicates that a device has been added to an existing call and that no devices have
been removed from the existing call.
• Get Switching Function Devices service – This service provides the list of endpoint identifiers that are
provided by the telephony platform. If this service is not supported, a voice browser application will have to
determine the endpoint identifiers outside of the ECMA-323 interface.
6 ECMA-323 Illustrative Examples
This section provides some examples of ECMA-323 XML messages (W3C Instance Documents) in the
context of voice browser usage scenarios. Examples include:
• discovering the features supported by a telephony platform
• establishing a monitor on a device (i.e. listen for incoming calls)
• notification of an inbound alerting connection
• answering an inbound connection, notification of a connected connection
• clearing a connection, notification of a cleared connection
• initiating an outbound call
• a single step transfer scenario
• a single step conference scenario
6.1 Discovering the Capabilities of a Telephony Platform
The ECMA-323 Get Switching Function Capabilities service can be used by a voice browser application to
determine the features (services and events) that a telephony platform supports.
See ECMA-323, 11.1.3, for the format of the information provided.
6.2 Starting a Monitor (i.e. listening for incoming calls)
In order to receive ECMA-323 call control events, a CSTA monitor must be placed on a telephony endpoint via
the ECMA-323 Monitor Start service.
6.2.1 Monitor Start – Service Request example
This example shows how a voice browser application places a monitor on an endpoint that is associated with
the identifier 22343. Note that by omitting the ECMA-323 optional parameters, the most relevant type of
monitoring (a device-type monitor on a device) is requested.
The mandatory Service Request parameters are:
• monitorObject – the device identifier of the endpoint. This can either be obtained by ECMA-323 (see 6.1)
or by mechanisms outside of ECMA-323.

8 © ISO/IEC 2004 – All rights reserved




22343


6.2.2 Monitor Start – Service Response example
This example shows the response to the Monitor Start request. The monitorCrossRefID of 99 will be provided
in all ECMA-323 events associated with this monitor request.
The mandatory Service Response parameters are:
• monitorCrossRefIdentifier – this parameter provides a handle to correlate subsequent ECMA-323 events
with this monitor request. Since each ECMA-323 event contains this handle, it can be used to associate
the event to the voice browser application that issued the Monitor Start request.


99

6.3 Notification of an Inbound Call
When an inbound call arrives at a monitored endpoint, an ECMA-323 Delivered event is provided by the
telephony platform.
The Delivered event contains information about the call such as ANI and DNIS information provided by the
network for example. This information enables a voice browser application to determine if it should answer the
call or reject it, how the call should be handled, etc.
6.3.1 Delivered Event example
The event contains the following parameters:
• monitorCrossRefID – this parameter represents the handle provided in the Monitor Start response.
• connection – this parameter contains connection identifier that is used in CSTA services that are to be
applied to this connection (e.g. Answer Call).
• alertingDevice – this parameter provides the endpoint identifier of the alerting connection. For inbound
calls, it is the endpoint on the voice browser platform. For outbound calls, the alerting device represents
the called device that is alerting.
• callingDevice – this is the local representation of the calling device. Due to features in the telephony
platform (transfers, forwarding, conferences, etc.) the calling device may have changed before it has
reached the voice browser platform.
• calledDevice – this is the local representation of the called device. Due to features in the telephony
platform (transfers, forwarding, conferences, etc.) the called device may have changed before it has
reached the voice browser platform.
• lastRedirectionDevice – indicates if the call has been previously redirected.
• localConnectionState – indicates the connection state of “alerting” at the near end connection. This will
typically be the connection associated with the monitored device on the voice browser platform.
© ISO/IEC 2004 – All rights reserved 9

• cause – indicates the cause of the event. In this case, it represents a “new” call.
• networkCallingDevice – for inbound calls, this represents the calling device information provided by the
network (ANI, for example). This information will always remain with the call and will never change (unlike
the callingDevice).
• networkCalledDevice – for inbound calls, this represents the called device information provided by the
network (DNIS, for example). This information will always remain with the call and will never change
(unlike the calledDevice).
• associatedCallingDevice – this parameter is provided when the call in an inbound call. The network
interface device identifier is 023 in this example. This could also be provided with the value of “notKnown”.


99

1
22343


22343


14085551212


22343




alerting
newCall

14085551212


18001234567


023


6.4 Answering an Inbound Call
After the voice browser application is notified of the incoming call it uses the ECMA-323 Answer Call service
to answer the call.
6.4.1 Answer Call – Service Request example
The mandatory Service Request parameters are:
• callToBeAnswered – the connection identifier of the alerting connection. The application uses the contents
of the connection parameter provided in the Delivered event.
10 © ISO/IEC 2004 – All rights reserved




1
22343


6.4.2 Answer Call – Service Response example
The telephony platform provides a positive response to the Answer Call service request. There are no
mandatory Service Request parameters.




6.5 Notification of a Connected Call
As the result of the Answer Call service, an ECMA-323 Established event is provided by the telephony
platform to indicate that the connection is now in the connected state.
If the telephony platform was configured to “auto-answer” the call, the Established event would be the first
event sent to the voice browser application.
6.5.1 Established Event example
Since the Estab
...