What does a business do when its existing telephone system can't handle additional users?

Until recently, the standard solution was to expand, to buy or to lease a new system, a process that is time-consuming and expensive.

Not any more. Now a business can leverage its existing investment in its private branch exchange (PBX) telephone systems and transform, or "migrate," them into Internet Protocol (IP)-based, multimedia communications systems.

Speaking at a recent technology forum, Henning Schulzrinne, associate professor of computer science and electrical engineering at Columbia's Fu Foundation School of Engineering and Applied Science, explained how businesses can upgrade their traditional telephone systems and add an array of multimedia features. The process would be both gradual and cost effective because the existing system would be used as a gateway to the new Internet-based system.

According to Schulzrinne, co-author of the Session Initiation Protocol or SIP, which is becoming the preferred standard for Internet telephony and multimedia applications, the migration from traditional communications to Internet telephony involves four steps:

Adding Internet Protocol (IP) phones to an existing PBX or Centrex system, making the PBX a gateway.

Adding multimedia capabilities such as audio, video, shared applications and chat to the system

Reversing the PBX by replacing the traditional public switched telephone network connection with a SIP over IP link to the carrier.

Retiring the traditional phones.

Web-based call routing, multiparty video conferencing and programmable call routing are all possible using SIP technology. The technology can also be used in "virtual worlds" to connect "avatars" (graphical representations of users in human-like form) via audio and video. Beyond traditional voice, SIP end systems can control household appliances and industrial equipment, provide instant messaging, and facilitate voiceXML, a scripting language for interactive voice response systems that makes "voice browsing" over the Internet possible.

The forum at which Schulzrinne spoke was co-sponsored by the Columbia's Computer Science Department and SIP Communications (SIPCOMM), which was formed in 1999 to commercialize Columbia's SIP technology, pursuant to license and research agreements executed that same year. It is a Columbia University portfolio company, launched by the University's technology transfer office, Science & Technology Ventures (S&TV). Schulzrinne serves as the company's chief scientific advisor. He is also director of Columbia's Real-time Internet Laboratory, where the SIP communications software was developed.

Commenting on the process of taking his technology from the laboratory to the marketplace, Schulzrinne said, "In general, take-up of Internet telephony has been slower than many people have anticipated. This shouldn't be too surprising since it requires replacing an existing infrastructure that mostly works well. I see the combination of existing services with new capabilities, rather than just replacing traditional telephone services, as the main incentive for the coming transition."

Schulzrinne described the commercialization process as a "learning experience for all involved," noting the recent difficulties in venture capital funding for telecommunications-related startups. He did, however, say that there has been significant progress in licensing the software, with more than one hundred licensees.

SIP is gaining acceptance in the industry. Microsoft is using SIP for its XP internet telephony. Worldcom is putting SIP into its network while CISCO is putting SIP into its routers and networking equipment. In addition, hundreds of companies are incorporating SIP applications in their network enterprises.

"Prof. Schulzrinne's demonstration vividly illustrates the practical uses of SIP technology today in the enterprise," said Joseph R. Flicek, president and CEO of SIP Communications, Inc. "Columbia's computer science SIP system is fully operational and has enabled the department to save money, serve new users and provide many advanced telecom services. Prof. Schulzrinne showed the potential of SIP to change the way people communicate in the future."

Flicek went on to comment on the value of the collaboration between Sip Communications and Columbia. "The partnership between the Columbia Computer Science Department, Science & Technology Ventures and SIPCOMM is advancing the deployment of SIP technologies," said Flicek.

Columbia's technology transfer office, S&TV, identifies, evaluates, protects and licenses the University's intellectual property, encouraging private sector funding for research and development.

"We have been involved in commercializing Columbia's technologies, but more than that we have created a way for the brilliant output of Columbia's scientists to benefit society. In that process, we look to returning the money to the University and the inventors so that they, in turn, can do more research," said Michael Cleare, Executive Director of Columbia's Science & Technology Ventures (S&TV).

By Loralee Nolletti

Session Initiation Protocol Tutorial

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