The Emergence of a
past few years, the trade press and voice and data product vendors have heralded the
arrival of a new era of communications. Their articles and brochures depicted a world in
which real-time mixed media communications on the corporate Local Area Network (LAN) becomes a widely used, business-useful
capability. With the click of a button, end users in this new era would be able to
communicate robustly with the richness of mixed media (voice, video, and data application
Corporations would begin to migrate all
corporate communications onto a single network reducing both cost and complexity.
Real-time and near real-time calling would join file server, E-mail server, and other
traditional LAN traffic on a single, merged network.
Collaboration using mixed media across
geographically dispersed locations would increase productivity and lower travel costs.
Telecommuting would become less isolating and more productive. The possibilities seemed to
be almost endless.
Many of those heralding this new arrival
predicted that the market for solutions would grow quickly. Others were more cautious,
noting there was really not a standard defining the interoperation of this type of
offering from different manufacturers.
Many vendors built products that used
proprietary call setup signaling or proprietary voice, video, and/or application sharing
protocols. To their credit, many of these offerings did provide a viable mixed media
conferencing service on customers’ data networks. Unfortunately, these products did
not interoperate with one another.
Potential customers, having experienced or
witnessed the headaches associated with trying to make different vendors’ data
products interoperate, were hesitant to buy these proprietary implementations. In the end,
those who were cautious were in much bigger numbers. As a result, the market developed
Essential to Market Growth
The players in the industry realized the
need for another approach to create this new market and generate revenue from their new
products in a more timely way. Seeking a cooperative way to leverage this market, many of
the vendors came together under the auspices of the International Telecommunications Union
(ITU), a United Nations agency based in Geneva, Switzerland, to formalize standards for
interoperation between their LAN-based mixed media communications products.
In 1990, the ITU sanctioned the H.320
suite of standards for audio compression and communications standards. It was now possible
to link narrow-band visual telephony and terminal equipment from different vendors on the
same conference. Effective deployment of cameras enabled users to see one another and
“still shots” of data and documents. H.320 used fractional T1, switched 56, and
Early deployments of H.320 were expensive,
which limited market acceptance. Some vendors produced an alternative that worked over
regular telephone lines (POTS) to gain market entry. This less-costly alternative had some
success, but it was limited by its low, irregular transmission quality, limited feature
set, and lack of interoperability. Mixed media was not yet ready for business-critical
The H.320 standards resulted in
significant, ground-breaking developments for ISDN-based collaboration. They paved the way
for subsequent standards (e.g., T.120, below) that further enriched mixed media
communications’ potential. LAN-based collaborations should similarly benefit from the
H.320 standards suite.
Later, the T.120 recommendation
established data protocols for multimedia conferencing in multi-vendor, data-only
conferences. It also added document sharing to any H.32X video- conference. This allowed
users to interactively collaborate in real-time by sharing applications. Coupled with the
H.320 standards, interactivity became more meaningful.
Early deployments of the more robust mixed
media capabilities were limited to point-to-point applications. This clearly limits its
usefulness to business, which often needs entire workgroup participation and/or
involvement of additional subject matter expertise on an ad hoc basis. Hence,
vendors today are turning away from point-to-point to concentrate more on platform
deployment of robust mixed media communications. This represents the market for greatest
business usefulness and long-term growth.
1990, momentum surrounding development for mixed media standards has grown. More than
ever, prospective purchasers require confidence of full mixed media interoperability to
make the required business investment. Vendors need to produce standards-compliant
services to meet that need and maximize market opportunities. Standards-setting efforts
support both concerns. The result of these efforts is a standard known as H.323, for
video-enabled telephony systems and equipment
for local area networks which provide a non-guaranteed quality of service. It forms the
basis for ensuring that the LAN-based offerings built by manufacturers are interoperable.
H.323 has rapidly gained wide acceptance within the industry as the leading standards
platform upon which to build LAN-based mixed media products. Among other things, the H.323
a protocol for controlling
access to and use of LAN for mixed media calling. This component is known as Registration,
Admission Control, and Status (RACS).
all the signaling required to
set up calls on non-guaranteed quality of service LANs. This component is based on the
ISDN Q.931 protocol, known as H.225 Call Control.
the required and optional
encoding and synchronization formats for the voice, video, and data streams to be
communicated between participants, and
a mechanism for negotiating
which encoding formats will be used for voice, video, and data exchange and for setting up
and tearing down these connections, known as H.245.
Since the ratification of H.323 Issue 1 in
May 1996, the vast majority of the players, large and small, in the mixed media
conferencing business have been building products that conform to H.323 standard. To
further ensure interoperability between their products, they joined together and formed an
interoperability testing effort under the umbrella of the Internet Engineering Task Force
(IETF). It is to this forum that vendors bring their evolving products and test them with
one another. Vendors now meet regularly to interconnect their products and run through a
series of tests to ensure that the products they offer to customers work well together.
Lucent Technologies leads the IETF Study
Group 15 work in development and refinement of standards in transport networks, switching
and transmission systems, and equipment (including the relevant signal processing
elements). Lucent also leads the IETF Study Group 16s work in mixed media service
definition and mixed media systems (including the associated terminals modems,
protocols, and signal processing).
Seeing the need for bridging the worlds of
voice, data, and video, Lucent introduced the MultiMedia Communications eXchange (MMCX).
The MMCX extends easy-to-use business telephony calling features to real-time voice, data,
and video collaboration sessions over local and wide area networks. As the first
H.323-enabled server in the market, the MMCX allows any standards-compliant endpoint to
serve as a practical business tool, enabling users to assign a telephone number to their
desktop, conference up to six parties for a mixed media session and route calls to voice
mail or covering extensions.
In addition, the MMCX enables any H.323
standards-compliant endpoint to take advantage of the following telephony-enabled
the ability to make telephone
calls out into the public telephone network,
use of the public telephone
network as a wide area network to call between server communities when high quality of
service is required,
use of server capabilities to
reduce the bandwidth used across these distances to reduce the cost of operation between
the server communities, and
the ability to use the Lucent
Technologies DEFINITY(r) ECS advanced features to which the MMCX provides access to
"traditional PBX" features, such as: call detail records, class of service, and
class of restriction, least-cost routing, hunt group access, etc.
Lucent Technologies extends
existing standards to provide features and value-adds that are not yet supported by the
H.323 standard. This allows the MMCX to be fully interoperable with other vendors
products while giving the flexibility to bring customers added features and functionality.
Of course, Lucent continues its work within the standards body to add these extensions to
H.323 where it makes sense to do so.
As the H.323 standard evolves and products
that allow use of LANs for real and near-real time communication become commonplace, look
to Lucent Technologies to: continue driving the standards so that they allow development
of new, more powerful features in H.323 products, develop H.323-based products that
provide the level of business-usefulness the market expects from Lucent Technologies, and
add value to the H.323-based offerings of other industry players.
As a driving force for standards, Lucent
Technologies is confident that mixed media communications will become a reality for the
industry as a whole. Business users will finally be able to realize the promise of the
merged voice and datanetworks.
Extracted from a white
paper on mixed media standards published
by Lucent Technologies in June 1997.