The Web has changed everything! In less than a decade, enterprises have
gone from a wary tolerance of the Internet, to an all-out rush to reinvent
themselves as e-Businesses. Web browsers have dramatically lowered the
barriers between people and information, providing rich media through the
click of a mouse. At the same time, Web development methodologies have
enabled faster and cheaper deployment of end-user information services, both
internal and external to the enterprise.
But how has the Internet changed how people communicate with each other?
Clearly, electronic mail is the Internet's first ï¿½killer app.ï¿½ More
recently, instant messaging has made inroads into the workplace. Each has
speed and cost advantages over ï¿½snailï¿½ mail, but in terms of expressive
power, each has relied almost exclusively on text ï¿½ a restricted subset of
what is available through traditional mail. On the voice front, VoIP has
provided network efficiencies and cost savings, although its affect on end
users has been very limited. Conversely, cell phones have profoundly
impacted how people work and play, but without fundamentally altering the
medium of exchange: Voice.
With all its media flexibility, why hasnï¿½t the Internet made a
significant change in interpersonal communications? Quite simply, because
its full potential will not be realized until we move beyond the simple
transport capabilities of the Internet and into the services capabilities of
the Web. In other words, Voice over IP is just a first step toward the
converged multimedia services offered through Voice over the Web.
Will the Web paradigm do for person-to-person communications what it has
done to information and transaction networking? Will it cross the
enterprise/service provider domains as has IP-enabled networking? Will it
put the end user back in control of his communications space? Will it enrich
how enterprises communicate with customers and enhance how people
collaborate? The answer is ï¿½yes,ï¿½ but the more important question is ï¿½how?ï¿½
Lessons Learned From Converged Applications
Given that the solution lies in converging communications across multiple
media, one place to see how these changes may play out is to look at
converged applications that already exist.
For years, PBXs have supported links to data servers across what are
called Computer Telephony Interfaces (CTI). The major area of application is
in contact centers allowing skill-based routing to the appropriate agents
and screen pops of customer information the moment an agent picks up the
call. In other words, CTI has been traditionally viewed as an enhancement to
an existing voice-driven system. The idea of linking PC desktops to
telephony systems via CTI has been a long-standing ï¿½insurmountable
opportunity.ï¿½ Itï¿½s an opportunity because leveraging the power of the PC
with telephony control could significantly enhance inter-person
communications, personalization, and mobility management of every agent. It
has seemed insurmountable because CTI application development and
integration into enterprise systems has been the realm of a relatively small
number of CTI application development specialists focused on environments
such as contact centers. The initial promise of convergence has not been
realized because of incompatibilities in the entrenched complexity in the
CTI and PC telephony models, and inefficient development paradigms unable to
quickly surmount those difficulties. In fact, many contact centers are
moving from traditional specialized software to Web-based interfaces to
benefit from reduced training and development costs.
Conferencing is another area that has moved toward convergence.
Room-to-room video conferencing has been widely deployed, driving the
development of the H.320 family of standards, which rely on significant
reuse of ISDN Q.931-based signaling. These protocols are sufficiently rich
to have branched beyond videoconferencing to drive the creation of VoIP
gatekeepers (providing telephone number-to-IP address translation and
various resource-management functions), PC clients including Microsoftï¿½s
NetMeeting, VoIP media gateways (e.g., to circuit switched networks), and
multi-point conferencing control units. However, many limitations have been
discovered in trying to scale these solutions cost-effectively, and creating
services that are broadly accessible. Although they introduce multiple
different media, they continue to carry some of the architectural baggage of
legacy voice networks, without benefiting from Web development
methodologies. In fact, we are seeing an increase in competing solutions
offering fledgling video and audio conferencing services on the Web.
Unified messaging, provided on traditional PBXs and VoIP systems,
provides a single interface to a converged inbox for e-mail, voice mail, and
fax. This allows users to receive their mail in whatever medium is most
convenient to them, wherever they are, and with whatever appliance they
wish. The human interface and generally ease of use are important attributes
of these applications. A constant challenge in the design of these systems
is the creation of a user interface that retains all the functionality in
each of its antecedents without introducing complexity. How do the existing
interfaces deal with e-mails that are listened to and voice mails that are
So what patterns have emerged? It is clear that most of these existing
converged applications are outgrowths of traditional communications models.
Although this often confers early ease of use advantages, it has a
longer-term effect of restricting the potential evolution. Also, it seems
that the systems richest in features often have the most difficulty evolving
beyond their initial focus. Perhaps it should not surprise us that each of
these applications is now being challenged by Web-based alternatives.
Unification By Design
So if the Web has already redefined information services and is in the
process of redefining purpose-built converged applications, how will it
redefine interpersonal communications? The clear answer is SIP, the Session
Initiation Protocol. SIP extends the Web paradigm just enough to provide
control over ï¿½sessionsï¿½ or calls. By avoiding the temptation to dictate
the characteristics of the media being carried, SIP is medium-agnostic, and
by virtue of not inventing its own addressing, SIP allows for unparalleled
flexibility. But most importantly, by growing out of a Web-based development
environment, it provides the quickest and cheapest integration into existing
and evolving information systems. Thus, SIP unifies the control and
management of diverse communications modes and acts as communications glue
across multiple environments and multiple media.
A simple, but useful, way to characterize the differences between SIP and
its predecessors is to separate communications into the control plane and
the data plane. SIP restricts itself to the control plane where it creates,
modifies and terminates sessions that contain two or more participants.
These sessions may include multimedia conferences, audio and video
streaming, multimedia distribution, or simple telephone calls. The data
plane, or ï¿½bearer path,ï¿½ defines how data, voice, image, or video is
transmitted over various transport networks including IP, ATM, and TDM,
whether wired or wireless. Without allowing for the separation of the
control and data plane, traditional communications application models lead
to vertically integrated applications controlling access from various
devices across multiple transport networks. A SIP-based application, on the
other hand, is unconcerned with the data plane, and thus adheres by design
to a peer-to-peer networking model.
The future of person-to-person multimedia communications is the Web
paradigm, with SIP as a unifying signaling and control plane protocol. What
Signaling System #7 (SS7) has done for the public telephone network, SIP
will do in bringing the Web paradigm to person-to-person communications
across a broad range of media. Telephony apps are buttons on Web pages. The
voice or video control panel is a Web browser, a PC application, a PDA
application, an IP-phone, or all of the above. Phone calls can terminate to
e-mail addresses or URLs. Like the Web, communications value and content can
be anywhere, more accessible than ever before. Best of all, a person can
make a multimedia call as simply as they place a voice call today.
Web-based Communications and Beyond
SIP-based communications will enable an array of new services that enhance
personal productivity across all media and all devices. Personalization
services will leverage user defined communication and call management
profiles. Mobility services will provide the flexibility to be reached
virtually ï¿½anytime, anywhereï¿½ on any device over any network.
Collaborative services, such as multimedia conferencing and screen sharing
will change the dynamics of workplace communications. In todayï¿½s world,
rudimentary methods are used to declare oneï¿½s willingness to be connected:
Only answering calls from specific callers (enabled by CLID and caller name
display), turning off cell phones when in meetings, or automatically
responding to e-mails with a canned message when away from the office. In
the emerging world enabled through SIP, people will be optionally able to
project a different connectivity image or ï¿½virtual presenceï¿½ (send me a
short message on my cell if my boss calls) of themselves to different
communities (family, management, peers, suppliers, and so on).
While there are always many ways of achieving a technical goal,
peer-to-peer networking through SIP, coupled with Web-style development
tools and XML-based data representation, is gaining acceptance across the
industry. Although Microsoft has a dominant position in H.323-based PC
clients with NetMeeting, they have migrated to SIP for the next generation
Windows XP Messenger client. Developing SIP agents in VoIP communication
servers and PBXs provides a valuable bridge between traditional VoIP
environments and the SIP world. SIP-based networking across enterprise and
service provider environments will further extend the reach of these
solutions and provide manage service solution opportunities. The ultimate
value of SIP may come when solutions are developed which combine its power
with the existing feature-rich worlds of PBXs, and carrier-based wire-line,
and wireless, telephony services.
End users are under increasing demands to do more with less time. They
are looking for communication capabilities that increase their personal
productivity, enable them to work when and where they want and enhance their
ability to personalize their services to their specific needs. Enterprises
are looking for ways to serve their customers better and more profitably. A
SIP-based control plane is a key technology that delivers on these values
and brings the Web paradigm to person-to-person communications.
Tony Rybczynski is director of strategic marketing and technologies
for Nortel Networksï¿½ Enterprise Solutions with 30 years experience in
networking. For more information, visit the company's Web site at www.nortelnetworks.com.
E-mail questions or comments to firstname.lastname@example.org.
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