June 2002

BY TONY RYBCZYNSKI

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 �killer app.� More recently, instant messaging has made inroads into the workplace. Each has speed and cost advantages over �snail� mail, but in terms of expressive power, each has relied almost exclusively on text � 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 hasn�t 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 �yes,� but the more important question is �how?�

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 �insurmountable opportunity.� It�s 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 Microsoft�s 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 read?

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 �sessions� 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 �bearer path,� 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 �anytime, anywhere� on any device over any network. Collaborative services, such as multimedia conferencing and screen sharing will change the dynamics of workplace communications. In today�s world, rudimentary methods are used to declare one�s 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 �virtual presence� (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 Networks� 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 [email protected].

[ Return To The June 2002 Table Of Contents ]