ISO/TR 16056-2:2004

Health informatics — Interoperability of telehealth systems and networks — Part 2: Real-time systems

ISO/TR 16056-2:2004 builds on the introduction to telehealth described in Part 1: Introduction and definitions, and focuses on the technical standards related to real-time applications (including video, audio, and data conferencing) and interoperability aspects of telehealth systems and networks. Specifically, this document addresses four main areas: Standards for real-time telehealth systems: The document describes the technical standards related to real-time telehealth applications, including audio, video, and data conferencing capabilities. It also identifies gaps, overlaps and inconsistencies in the standards, and provides some guidance about how they need to evolve. Interoperability issues in telehealth applications: The document examines interoperability aspects of real-time multimedia conferencing standards and telehealth products, and identifies areas of concern from the interoperability perspective that need to be resolved. Requirements for interoperable telehealth systems and networks: The document defines interoperability requirements at different levels of interaction between telehealth systems and provides some guidelines on how interoperability can be achieved. Framework for interoperable architectures: The document identifies interoperable building blocks for telehealth solutions and interactions between these building blocks, and explores the possibility of standardization of these building blocks. The scope of the document does not include conformity and interoperability tests or functional specifications for telehealth systems and networks.

Informatique de santé — Interopérabilité des systèmes et des réseaux de télésanté — Partie 2: Systèmes en temps réel

General Information

• Status: Published
• Publication Date: 23-Jun-2004
• ICS: 35.240.80 - IT applications in health care technology
• Technical Committee: ISO/TC 215 - Health informatics
• Drafting Committee: ISO/TC 215/WG 2 - Systems and Device Interoperability
• Current Stage: 6060 - International Standard published
• Start Date: 24-Jun-2004
• Completion Date: 14-Feb-2026

Overview

ISO/TR 16056-2:2004 - "Health informatics - Interoperability of telehealth systems and networks - Part 2: Real-time systems" is an informative Technical Report that focuses on real-time telehealth interoperability. Building on Part 1 (Introduction and definitions), it surveys technical standards for synchronous telehealth services (audio, video and data conferencing), identifies gaps and inconsistencies, and provides guidance on achieving interoperable real-time telehealth systems and networks. The report is descriptive (a Technical Report), and explicitly does not include conformity tests or detailed functional specifications.

Key topics and technical requirements

• Multimedia conferencing standards: analysis of relevant standards and recommendations used in real-time telehealth, including families such as H.320, H.321, H.323, H.324 and T.120 for audio/video/data conferencing and collaborative data channels.
• Interoperability issues: identification of common sources of interoperability failures - e.g., gaps and overlaps in standards, loosely defined mandatory/optional features, encoding/decoding inconsistencies, evolving specifications for Gateways/Gatekeepers/MCUs, and bandwidth/media management concerns.
• Interoperability requirements: practical requirements defined across interaction levels, including call setup, acquisition/processing/transmission of multimedia data, control of near- and far-end devices, and call termination.
• Heterogeneous network considerations: guidance for interoperability across mixed network environments (for example, H.320 services over frame relay and other cross-network scenarios) and the role of gatekeepers and MCUs.
• Framework for interoperable architectures: identification of interoperable building blocks and component boundaries - User interface, Medical devices, Data manager, Processing manager, Communications manager, Resource manager, Integration manager - to support modular, standard-aligned telehealth solutions.

Practical applications and who uses it

ISO/TR 16056-2 is valuable for:

• Telehealth system architects and designers planning real-time audio/video/data conferencing solutions.
• Vendors and integrators implementing interoperable teleconsultation, telelearning, and remote monitoring products.
• Health IT managers and clinical program leads selecting equipment and services with interoperability in mind.
• Standards bodies and policy makers assessing gaps and harmonization needs in telehealth standards.

The report helps stakeholders understand where standards enable interoperability, where standards gaps or proprietary implementations create risks, and how to design systems that better interoperate across heterogeneous networks and products.

Related standards

• ISO/TR 16056-1: Part 1 - Introduction and definitions (companion document)
• ITU-T multimedia and conferencing recommendations: H.320, H.321, H.323, H.324, T.120 (surveyed in the report)

Keywords: telehealth interoperability, real-time telehealth systems, multimedia conferencing standards, H.323, H.320, T.120, teleconsultation, telelearning, interoperable telehealth architecture.

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 16056-2
First edition
2004-07-01
Health informatics — Interoperability of
telehealth systems and networks —
Part 2:
Real-time systems
Informatique de santé — Interopérabilité des systèmes et des réseaux
de télésanté —
Partie 2: Systèmes en temps réel

Reference number
©
ISO 2004
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ii © ISO 2004 – All rights reserved

ISO TR 16056-2:2004(E)
Contents Page
Foreword . v
Introduction. vi
1 Scope . 1
2 Normative References. 1
3 Terms and definitions . 2
4 Abbreviations . 12
5 Multimedia Conferencing Standards . 13
5.1 General . 13
5.2 H.320 recommendations . 16
5.3 H.321 and H.310 Recommendations . 17
5.4 H.323 Recommendations . 19
5.4.1 H.323 Terminals . 19
5.4.2 Gateways. 21
5.4.3 Gatekeeper . 21
5.4.4 Multipoint control unit . 21
5.5 H.324 Recommendations . 22
5.6 T.120 Recommendations . 23
5.6.1 T120 Overview. 23
5.6.2 T.120 Layer composition. 23
5.6.3 T.120 Interoperability.24
6 Telehealth applications . 24
6.1 General . 24
6.2 Telelearning . 25
6.3 Teleconsultation . 26
7 Interoperability issues . 28
7.1 General . 28
7.2 Standard-related sources of interoperability issues. 28
7.2.1 Loose adaptation of previous protocols. 29
7.2.2 Loosely defined encoding and decoding methods. 29
7.2.3 Inconsistent definition of mandatory/optional requirements. 29
7.2.4 Gaps in the recommendations. 29
7.2.5 No specifications for data encoding in the H.320/H.323 Recommendations . 30
7.2.6 Evolving T.120 Recommendations. 30
7.2.7 Loosely defined specifications for an MCU. 30
7.2.8 Evolving/undefined specifications for Gateways and Gatekeepers . 30

7.2.9 Loosely defined bandwidth management. 31
7.2.10 Poor standardization of media conferencing . 31
7.3 Product-related Sources of Interoperability Issues . 31
7.3.1 Time delay between the standards (ever-evolving) and products . 31
7.3.2 Implementation of a different subset of the standards. 32
7.3.3 Proprietary solutions. 32
7.4 Implementation-related sources of interoperability issues. 32
7.4.1 Undefined specifications for Gatekeeper Communication. 32
7.4.2 Gateway to Gatekeeper Communication. 32
7.4.3 A decentralized multipoint conference . 33
8 Interoperability requirements. 33
8.1 General . 33
8.2 Call Setup. 34
8.3 Acquisition, processing, and transmission of multimedia data . 35
8.4 Controlling near- and far-end devices .36
ISO TR 16056-2:2004(E)
8.5 Call termination. 36
9 Interoperability in heterogeneous telehealth networks . 36
9.1 General . 36
9.2 Interoperability of H.320 systems over frame relay network. 36
9.3 Interoperability of h.3xx-compliant systems over heterogeneous networks. 37
9.3.1 Gatekeeper functions. 38
9.3.2 MCU functions. 39
9.3.3 Design requirements – Telehealth solutions . 40
10 Framework for interoperable architectures. 41
10.1 General . 41
10.2 Telehealth component boundaries.41
10.2.1 User interface . 41
10.2.2 Medical Devices . 42
10.2.3 Data manager . 42
10.2.4 Processing Manager . 42
10.2.5 Communications Manager . 43
10.2.6 Resource Manager . 43
10.2.7 Integration Manager. 43
Bibliography. 45

List of Figures
Figure 1 - The H.320 Terminal . 16
Figure 2 - A multipoint configuration. 17
Figure 3 - The H.321 Terminal . 18
Figure 4 - The H.323 Terminal . 20
Figure 5 - The H.324 Terminal . 22
Figure 6 - The T.120 Recommendations. 23
Figure 7 - Parties contributing to telehealth interoperability. 28
Figure 8 - Interoperability dimensions for real-time telehealth services . 34
Figure 9 - H.320 video services incorporated into existing data and voice networks over frame relay . 37
Figure 10 - Connectivity in a heterogeneous system and network environment. 38

List of Tables
Table 1 - Summary of the multimedia conferencing standards. 15
Table 2 - Summary of the H.320 Recommendations. 17
Table 3 - The H.323 and T.120 protocol stack . 20
Table 4 - Summary of the H.323 Recommendations. 21
Table 5 - Summary of functionality of a telelearning system . 25
Table 6 - Summary of functionality of a teleconsultation system . 26

iv
ISO TR 16056-2:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a 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), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides 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 shall not be held responsible for identifying any or all such patent rights.
ISO/TR 16056-2 was prepared by Technical Committee ISO/TC 215, Health informatics.
ISO/TR 16056 consists of the following parts, under the general title Health informatics — Interoperability of
telehealth systems and networks:
 Part 1: Introduction and definitions
 Part 2: Real-time systems
ISO TR 16056-2:2004(E)
Introduction
Delivery of health care services by means of telehealth is advancing rapidly. Telehealth enables providing these
services with the use of information and telecommunications technologies. This includes a broad spectrum of
capabilities including acquisition, storage, presentation, and management of patient information (represented in
different digital forms such as video, audio, or data), and communication of this information between care facilities
with the use of communications links.
Telehealth interactions may be carried out in three ways: real-time, store-and-forward or with the use media
streaming methods. While real-time interactions imply that all parties directly participate in the telehealth session,
store-and-forward interactions involve sending, reviewing, and returning an opinion over a period of time.
Streaming is a method of delivery real-time or stored data such as audio, video, documents, still images, or other
data type across networks with a reasonable amount of Quality of Services (QoS). With streaming, a receiving
system can start displaying (or playing) the data before the entire content arrives.
Real-time telehealth sessions usually involve synchronous data transmission while store-and-forward can usually
be regarded as asynchronous. Streaming uses time-synchronized streams of continuous media during
transmission. However, data presentation uses buffering, if the receiving system receives data more quickly than
required. If the data is not received quickly enough, the presentation of the data is interrupted.
Interoperability of telehealth systems and networks is critical in ensuring the telehealth technology serves well the
care recipients and providers and meets their expectations. While this requirement is essential to the long-term
sustainability of telehealth, interoperability is difficult to achieve. There are many reasons that make telehealth
interoperability difficult, however, the following three need urgent addressing: (1) too broad definition of telehealth,
(2) lack of standards specifically designed for telehealth, and (3) collaboration between the information technology
and telecommunications industries.
There are multiple definitions of telehealth. The services provided by telehealth cover a broad spectrum of
activities ranging from videoconferencing through exchange of health information to providing care services in
emergency and complex clinical cases. From a technology perspective, the scope of these services is too broad
and this makes it difficult to develop telehealth standards and products.
There is no ‘official’ telehealth standard. The telehealth industry uses high-level health care guidelines and
technical standards developed for various technology sectors including multimedia conferencing, information
technology, data communications, and security. These guidelines and standards focus on functional and
operational requirements and do not address interoperability. To further complicate the problem, all of these
standards as well as the telehealth needs and practices are rapidly changing.
Telehealth, more than any other recent development, bridges the boundaries between telecommunications and
information technologies. The business goals and attitudes of these two industries are different.
Telecommunications industry has a history of regulation, standardization, and control of the customer premises
equipment. Interoperability and reliability have been the key factors to growth. The information technology industry
(the desktop computing industry in particular) has achieved success through encouraging innovation, diversity,
and tremendous cost-efficiency not always paying attention to interoperability aspects of the technology. The
marriage of these two cultures and the integration of their respective technologies proved to be challenging.
To address the needs for interoperable telehealth systems and networks, telehealth services must be clearly
defined in terms of their scope and interrelationships with other health-related services, a set of telehealth-specific
standards must be developed, and subsequently implemented by the respective industries.
This two-part ISO Technical Report addresses interoperability issues in telehealth systems and networks. This
document has been structured as follows:
Part 1: Introduction and definitions. Covers an introduction to telehealth and includes the definitions of
telehealth, interoperability, and related terms.
Part 2: Real-time systems. Defines the scope of the technical standards related to real-time applications,
(including video, audio, and data conferencing), identifies gaps and overlaps in the standards, defines
requirements for interoperable telehealth systems and networks, and identifies building blocks for
interoperable telehealth solutions.
vi
ISO TR 16056-2:2004(E)
This Technical Report is to be complemented by two other documents that will cover interoperability of store-and-
forward and media streaming telehealth applications.
The target users of these documents are care providers and health care organizations, telehealth equipment
vendors and implementers of telehealth solutions, professional organizations, and governments.

ISO TR 16056-2:2004(E)
Health informatics — Interoperability of telehealth systems and
networks — Part 2: Real-time systems
1 SCOPE
This Technical Report entitled Interoperability of telehealth systems and networks – Part 2: Real-time systems
builds on the introduction to telehealth described in ISO/IEC TR 16056-1 Health informatics - Interoperability of
telehealth systems and networks - Part 1: Introduction and definitions and focuses on the technical standards
related to real-time applications, (including video, audio, and data conferencing) and interoperability aspects of
telehealth systems and networks.
Specifically, this document addresses four main areas:
i) Standards for real-time telehealth systems. This Technical Report describes the technical standards
related to real-time telehealth applications, including audio, video, and data conferencing capabilities. It also
identifies gaps, overlaps and inconsistencies in the standards, and provides some guidance about how they
need to evolve.
ii) Interoperability issues in telehealth applications. This Technical Report examines interoperability aspects
of real-time multimedia conferencing standards and telehealth products, and identifies areas of concerns from
the interoperability perspective that need to be resolved.
iii) Requirements for interoperable telehealth systems and networks. This Technical Report defines
interoperability requirements at different levels of interaction between telehealth systems and provides some
guidelines on how interoperability can be achieved.
iv) Framework for interoperable architectures. This Technical Report identifies interoperable building blocks
for telehealth solutions and interactions between these building blocks, and explores the possibility of
standardization of these building blocks.
The scope of the Technical Report does not include conformity and interoperability tests or functional specifications
for telehealth systems and networks.
2 NORMATIVE REFERENCES
This Technical Report incorporates by dated or undated reference, provisions from other publications. These
normative references are cited in the appropriate places in the text, and the publications are listed hereafter.
For dated references, subsequent amendments and revisions of any of these publications apply to this ISO
Technical Report only when incorporated in it by amendment and revision. For undated references, the latest
edition of the referenced document (including any amendments) applies.
CEN/TC 251/N99-097       Health Informatics - Interoperability of Healthcare Multimedia Report
(1999) Systems. Final draft CEN Report
ISO/IEC 17000:2004 Conformity assessment – Vocabulary and general principles
ITU-T Recommendation G.711
Pulse code modulation (PCM) of voice frequencies.
(1988)
ITU-T Recommendation G.722
7 KHz audio - coding within 64 kbit/s.
(1993)
ITU-T Recommendation G.728 Coding of speech at 16 kbit/s using low-delay code excited linear
(1992) prediction.
ITU-T Recommendation H.221
Frame structure for a 64 to 1920 kbit/s channel in audiovisual teleservices.
(1993)
ISO TR 16056-2:2004(E)
ITU-T Recommendation H.230
Frame-synchronous control and indication signals for audiovisual systems.
(1997)
ITU-T Recommendation H.242 System for establishing communication between audiovisual terminals using
(1996) digital channels up to 2 Mbit/s.
ITU-T Recommendation H.243  Procedures for establishing communication between three or more
(1997) audiovisual terminals using digital channels up to 1920 kbit/s.
ITU-T Recommendation H.224  A real time control protocol for simplex applications using the H.221
(1994) LSD/HSD/HLP channels.
ITU-T Recommendation H.281  A far end camera control protocol for videoconferences using H.224.
(1994)
ITU-T Recommendation H.233  Confidentiality System for Audiovisual Services.
(1996)
ITU-T Recommendation H.234  Encryption key management and authentication system for audiovisual services.
(1996)
ITU-T Recommendation H.320 Narrow-band visual telephone systems and terminal equipment.
(1996)
ITU-T Recommendation T.120
Data protocols for multimedia conferencing.
(1996)
ITU-T Recommendation T.121
Generic application template.
(1996)
ITU-T Recommendation T.122 Multipoint communication service for audiographics and audiovisual
(1993) conferencing service definition.
ITU-T Recommendation T.123 Protocol stacks for audiographic and audiovisual teleconference
(1994) applications.
ITU-T Recommendation T.124
Generic conference control.
(1995)
ITU-T Recommendation T.125
Multipoint communication service protocol specification.
(1994)
ITU-T Recommendation T.126
Multipoint still image and annotation protocol.
(1995)
ITU-T Recommendation T.127
Multipoint binary file transfer protocol.
(1995)
3 TERMS AND DEFINITIONS
For the purposes of this Technical Report, the following definitions apply.
3.1
accreditation
third party attestation related to a conformity assessment body conveying formal demonstration of its competence
to carry out specific conformity assessment tasks

2 © ISO 2004 – All rights reserved

ISO TR 16056-2:2004(E)
3.2
A-law
variant of the G.711 audio encoding used primarily in North America and Japan
NOTE Related terms include µ-law and G.711
3.3
asynchronous transmission
transmission of individual bytes without time-dependency between the bytes
3.4
audiographics terminal
terminal that has audio and graphics capabilities, but no video capability
3.5
audiovisual terminal
terminal that has audio, video, and graphics capabilities
3.6
basic rate interface
BRI
ISDN service comprising two B (bearer) channels operating at 64 Kbps each and one D (data) channel operating at
16 Kbps
3.7
call
point-to-point multimedia communication between two H.32x endpoints
3.8
call setup
process of establishing a group of communication users and includes the initialization of any shared application and
other resources which the user may require to be available
3.9
call signalling channel
reliable channel used to convey call setup messages following Q.931
3.10
call teardown
process of ending a call and freeing any resources reserved for that call
3.11
centralized multipoint conference
conference call in which all participating terminals communicate in a point-to-point fashion with an MCU
3.12
certification
third-party attestation related to products, processes, systems or persons
NOTE 1 Certification of a management system is sometimes also called registration.
NOTE 2 Certification is applicable to all objects of conformity assessment except for conformity assessment bodies
themselves, to which accreditation is applicable.
ISO TR 16056-2:2004(E)
3.13
channel service unit
CSU
interface used to connect a terminal or computer to a digital medium in the same way that a modem is used for
connection to an analogue medium
3.14
charge coupled device
CCD
device used in cameras as an optical scanning mechanism.
NOTE It consists of a shift register that stores samples of analog signals. An analog charge is sequentially passed along
the device by the action of stepping voltages and stored in potential wells formed under electrodes. The charge is moved from
one well to another by the stepping voltages.
3.15
COder/DECoder
COmpression/DECompression
CODEC
hardware and/or software used with interactive video systems that converts an analog signal to digital, then
compresses it so that lower bandwidth telecommunications lines can be used
NOTE The signal is decompressed and converted back to analog output by a compatible CODEC at the receiving end. The
compression method (algorithm) may be proprietary or standards -based.
3.16
common intermediate format
CIF
ITU-T standard video picture scanning format where information is stored in luminance (brightness) and two color
difference (chrominance) components
NOTE CIF represents 352 pixels/line by 288 lines/image for luminance and 176 pixels/line by 144 lines/image for
chrominance. See also QCIF.
3.17
composite video
type of video signal in which all information -- the red, blue, and green signals, and sometimes audio signals as well,
are mixed together
NOTE Composite video is used by NTSC-compliant devices (see NTSC Standard).
3.18
conformity assessment
demonstration that specified requirements relating to a product, process, system, person or body are fulfilled
NOTE Conformity to a set of specifications is a prerequisite to interoperability. However, conformity to the specifications
alone does not guarantee interoperability of systems.
3.19
data service unit
DSU
device used in digital transmission for connecting a CSU to data terminal equipment (a terminal or computer), in the
same way that a modem is used for connection to an analogue medium
Note See also CSU.
3.20
decentralized multipoint conference
conference in which the participating terminals multicast to all other participating terminals without an MCU
4 © ISO 2004 – All rights reserved

ISO TR 16056-2:2004(E)
3.21
endpoint
terminal, gateway, or MCU
3.22
G.711
ITU-T recommendation for the digital representation of speech up to 3.4 KHz of frequency producing a 64 Kbps
data stream
NOTE Commonly used in telephone networks. It comes in two variants: A-law and µ-law.
3.23
G.722
ITU-T recommendation for the digital representation of audio up to 7 KHz of frequency producing a 64 Kbps data
stream with a much higher quality than G.711
3.24
G.728
ITU-T recommendation for the digital representation of audio producing a 16 Kbps data stream producing near-
telephone quality audio.
3.25
gatekeeper
H.323 entity that provides address translation, control access, and sometimes bandwidth management to the LAN
for H.323 terminals, gateways, and MCUs
3.26
gateway
H.323 entity, which provides real-time, two-way communications between H.323 terminals on the LAN and other
ITU terminals on a WAN, or to another H.323 gateway
3.27
generic conference call
GCC
set of conference services described in the ITU-T T.124 Recommendation
3.28
H.221
ITU-T recommendation defining how to multiplex video and audio into frames using 64-1920 Kbps channels for
switched and leased network services, excluding packetized networks
3.29
H.225D
ITU-T recommendation that specifies messages for call control including signaling, registration and admissions,
and packetization/synchronization of media systems
3.30
H.230
ITU-T recommendation that specifies the frame-synchronous control and indication signals for audiovisual systems
3.31
H.231
ITU-T recommendation that specifies the multipoint control unit
3.32
H.235
ITU-T recommendation that defines the security framework used to provide authentication, encryption, and integrity
for H.323 systems
ISO TR 16056-2:2004(E)
3.33
H.242
ITU-T recommendation that specifies how to establish the communication between audiovisual terminals using
digital channels with speeds up to 2 Mbps
3.34
H.243
ITU-T recommendation that specifies the establishment of communication between three or more audiovisual
terminals using digital channels with speeds up to 2 Mbps
3.35
H.245
ITU-T recommendation that specifies messages for opening and closing channels for media streams, and other
commends, requests and indications between two H.323 endpoints
3.36
H.261
ITU-T recommendation that specifies the video encoding and compression algorithm for two video resolutions: 352
x 288 CIF and 176 x 144 QCIF
NOTE H.261 is used in both H.320 and T.120.
3.37
H.263
ITU-T recommendation that specifies a new video codec for video over packet-switched networks or POTS
NOTE H.263 optimizes H.261 for very low bit rate of video coding below 64 Kbps. H.263 provides better motion
compensation, more accurate motion vectors, optimized quantization for very low bit rates, and arithmetic coding.
3.38
H.310
family of ITU-T standards ratified in 1995 that describes the technical specifications for adapting narrow-band ISDN
visual telephone terminals, as defined in H.320, to broadband ISDN (BISDN) and ATM environments
NOTE H.310 adds the MPEG-2 video-compression algorithm that provides MPEG-2 video quality.
3.39
H.320
family of ITU-T standards, ratified in 1990, that specifies how voice and video conferencing systems communicate
over ISDN or leased networks, using a bandwidth from 64 Kbps to 1920 Kbps
3.40
H.323
family of ITU-T standards, ratified in 1996, that extends H.320 to computer networks, including LANs and the
Internet
NOTE H.323 supports both point-to-point and multipoint operations. In addition, H.323 shares many components of the
H.32x specification, such as the H.261 video codec, the G.711 audio codec, the H.263 video codec, G.722, G.723 and G.728.
As a new feature, H.323 specifies a gatekeeper component that allows LAN administrators to manage video traffic for QoS. The
H.323 specification also defines a LAN/H.320 gateway that permits a H.323 node to interoperate with H.320/H.324 terminals.
3.41
H.324
family of ITU-T standards, ratified in 1996, that allows video conferencing over standard analog phone lines with
features similar to those in H.320
NOTE The H.324 standard uses H.263, which contains a better codec for POTS than H.261. H.263 is an improved version
of H.261 that adds a 128 x 96 sub-QCIF (SQCIF) format. By using a 28.8 or 36.6 Kbps modem, H.263 may produce frame rates
approaching those achieved by H.320 systems over ISDN.
6 © ISO 2004 – All rights reserved

ISO TR 16056-2:2004(E)
3.42
interoperability
the ability of two or more systems (computers, communication devices, networks, software, and other information
technology components) to interact with one another and exchange information according to a prescribed method
in order to achieve predictable results
3.43
interoperability testing
an assessment of the ability of two or more systems to interact with one another and exchange usable electronic
data
NOTE As conformity to the specifications alone does not guarantee interoperability of systems, interoperability testing is
required to assess the ability of two or more systems to interact with one another and exchange usable electronic data.
Interoperability testing does not include assessment of performance, robustness or reliability nor does it measure the conformity
of an implementation. Two systems can be interoperable but still not compliant to the standard or specification.
3.44
µ-law
variant of the G.711 audio encoding used primarily in North America and Japan
NOTE See also G.711 and A-law.
3.45
multipoint control unit
MCU
endpoint on the LAN which enables three or more terminals and gateways to participate in a multipoint conference
NOTE The MCU includes a mandatory MC and optional MPs.
3.46
multipoint controller
MC
An entity that provides for the control of three or more terminals in a multipoint conference
3.47
multipoint processor
MP
entity that provides for the processing of audio, video, and/or data streams in a multipoint conference
NOTE The MP provides for the mixing, switching, or other processing of media streams under the control of the MC.
3.48
multipoint conference
conference between three or more terminals, which may be on the LAN or on the circuit switched network
3.49
NTSC Standard
standard for television broadcasting established by the National Television Standards Committee (NTSC)
NOTE Used in North America, Japan and some other countries. NTSC format: Lines / frame: 525; Frames per second (fps):
30; Interlace ratio: 2:1; Aspect ratio: 4:3; Color matrix equation: Y = 0.3*R + 0.59*G + 0.11*B; I = 0.6*R – 0.28*G - 0.32*B; Q =
0.21*R – 0.52*G + 0.31 * B; where R = red, G = green, and B = blue.
3.50
point-to-point protocol
protocol defined in RFC 1661, the Internet standard for transmitting network layer datagrams (e.g. IP packets) over
serial point-to-point links
ISO TR 16056-2:2004(E)
3.51
primary rate interface
PRI
ISDN service comprising 23 B (bearer) channels operating at 64 Kbps each and one D (data) channel operating at
16 Kbps
3.52
pulse code modulation
technique of used for the digital sampling of sound
NOTE The input waveform with a bandwidth up to 4.0 KHz is sampled at the recommended rate of 8,000 samples per
second. Each sample is converted to one of 212 digital values and then compressed on either the A-law or the µ-law. This
sampling scheme is adequate for voice communication.
3.53
quality of service
QoS
set of network technologies that enable a network to handle data traffic with a minimum amount of negative effects
in a network environment used by many other users
NOTE Subscribers of QoS specify requirements in service-level agreements (SLAs) regarding throughput, packet loss,
latency, and jitter.
3.54
quarter common intermediate format
QCIF
represents 176 pixels/line by 144 lines/image for luminance and 88 pixels/line by 72 lines/image for chrominance
NOTE See also CIF.
3.55
real-time streaming protocol
RTSP
application-level protocol that establishes and controls one or more time-synchronized streams of continuous
media
NOTE RTSP has been designed to serve up multimedia from a cluster of hosts and acts as a network remote control for
multimedia servers.
3.56
real-time transport protocol
RTP
data communication protocol capable of delivering real-time data such as live or interactive audio and video over IP
packet-switched networks
NOTE RTP runs over UDP and uses its multiplexing and error checking features.
3.57
specified requirement
need or expectation that is stated
NOTE Specified requirements can be stated in normative documents such as regulations, standards and technical
specifications. Specific requirements are intended to define some feature of a real implementation and offer the possibility of
testing.
3.58
synchronized multimedia integration language
SMIL
enables simple authoring of interactive audiovisual presentations
NOTE SMIL is typically used for rich media/multimedia presentations, which integrate streaming audio and video with
images, text or any other media type.
8 © ISO 2004 – All rights reserved

ISO TR 16056-2:2004(E)
3.59
synchronous transmission
data communications in which transmissions are sent at a fixed rate, with the sending and receiving devices
synchronized
3.60
T.120
family of ITU-T standards, ratified in 1996, that defines collaborative document sharing and whiteboard activities
NOTE The T.120 standards provide the audiographic portion of the H.320, H.323 and H.324 families. They also work
independently as an audiographic conference for a low-bandwidth channel. The whiteboard capability provides document-
sharing functions for multiple users so that they can simultaneously view and annotate a document with pens, highlighters and
drawing tools. This specification also allows data-only T.120 sessions when no video communications are required or provided.
In addition, T. 120 supports multipoint meetings in which the participants use different transmission media.
3.61
T.121
ITU-T standard that provides a generic application template (GAT), which specifies a common set of guidelines for
building application protocols and the management facility that controls the resources used by the application
NOTE T.121 also describes how an application protocol, such as T.127 for file transfer, performs the following functions:
- Registers itself with the conference.
- Applies its capabilities locally and remotely.
- Interoperates and negotiates capabilities with other applications.
To ensure application consistency, T.121 is a required standard for products developed under T.120. The ITU also recommends
that non-standard applications incorporate T.121 to provide product interoperability.
3.62
T.122
ITU-T standard that defines the multipoint services, which allow one or more participants to send data as part of a
conference
NOTE These multipoint services are implemented by T.125, which provides the mechanism for transporting the data.
Together, the T.122 and T.125 standards make up the T.120 multipoint communication services (MCS).
3.63
T.123
ITU-T standard that defines the transport and sequencing of data, and for controlling the flow of data across
networks, including connect, disconnect, send, and receive functions
NOTE For data transport, T.123 defines a series of network interface profiles. Also, T.123 provides an error-correcting
mechanism that ensures accurate and reliable data delivery. T.123 Annex B, an addition to the T.123 data conferencing
standard, also defines the protocol for secure data conferencing.
3.64
T.124
ITU-T standard that provides the generic conference control (GCC) for initiating and administering multipoint data
conferences.
NOTE The GCC performs the following functions:
- Serves as the information centre, directing users and data in and out of conferences and monitoring progress so that the
latest conference information is always available,
- Maintains lists of conference participants and their applications; the GCC identifies compatible applications and features so
that products can interoperate, and
ISO TR 16056-2:2004(E)
- Tracks MCS resources so that conflicts do not occur when conference participants use multiple application protocols, such
as T.127 for file transfer and T.128 for application sharing.
3.65
T.125
ITU-T standard that specifies how data is transmitted within a conference
NOTE T.125 defines the private and broadcast channels that transport the data, and ensures accurate and efficient
communication among multiple users. T.125 also implements the multipoint services defined by T.122.
3.66
T.126
ITU-T standard that specifies how an application sends and receives whiteboard information, in either compressed
or uncompressed form, for viewing and updating among multiple conference participants
NOTE The role of T.126 is to manage the multi-user workspace provided by the whiteboard.
3.67
T.127
ITU-T standard that defines how files are transferred simultaneously among conference participants
NOTE T.127 (also known as T.MBTF for Multipoint binary file transfer) enables one or more files to be selected and
transmitted in compressed
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