Moving ISDN-Based Videoconferencing onto the IP Network
by John Bartlett
Posted 7/2004; Published 11/2003




Driven by cost, efficiency and quality concerns, the installed base of ISDN (H.320) videoconferencing users is moving to IP (H.323). Often this comes as part of a broader consolidation of circuit-switched traffic onto IP packet backbones. This article briefly explains why this move is afoot, and discusses factors that contribute to a successful transition.


First of all, corporate decision-making in the post bubble telecom world is driven primarily by cost. ISDN-based videoconferencing is a visible and useful service in most large corporations, but it can be expensive.


Many organizations look at the unused capacity in their IP packet data networks as a potentially “free” substitute for the dedicated ISDN lines. Some also think their IP networking staff could take over for the people who have been running their ISDN videoconferences. And features of the newer H.323 systems, like centralized management and simplified call setup for users, also help cut costs and improve efficiency.


These features improve on the older, ISDN-based systems that required trained staff at each videoconferencing site to maintain the equipment, establish calls and monitor call quality on finicky ISDN lines. With H.323, the requirements for IT support staff can be reduced, and smaller centralized staffs can support larger deployments.


Another major driver for conversion to IP is call quality. ISDN lines have a habit of developing bit loss, and of then dropping out, requiring either manual or automatic redialing. Meanwhile the conference is either on hold or operating at a much poorer level of video quality, because it is trying to function on the remaining bandwidth.


Another factor to consider is that ISDN is no longer a primary focus for the telecom providers, so its quality is not likely to improve dramatically, whereas IP is a big focus both for the carriers and for the enterprise.


Before making the conversion, however, four areas must be addressed:



Business case


Videoconferencing architecture


IP network evaluation


Transition planning


Attending carefully to all four will ensure a smooth transition, and that no conferencing or networking functions will be lost along the way.


About the author:

John Bartlett is a vice president at NetForecast, where he focuses on real-time traffic, Internet performance and quality of service (QOS) techniques.



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