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Second Quarter 1998

Alon Cohen on: Version 2 of H.323 

By Greg Galitzine

 On February 6, 1998, the International Telecommunications Union met to discuss (among other things) version 2 of the H.323 standard.

I had a chance to speak with Alone Cohen, CTO at VocalTec Communications, Ltd., regarding the potential impact of the ITT’s decision, the differences between the new and existing versions of H.323, and VocalTec's participation in all of this. The following is a result of that conversation. I'd also like to thank Marty Querzoli of LNS Communications for his help in setting up this interview for INTERNET TELEPHONY™.

IT: How will the intended industry impact of version 2 differ from that of version 1?
AC: While version 1 dealt mainly at the LAN level, version 2 creates the playing field for the future of the IP communications industry, establishing standards for WANs, or large intranets, right up to the full Internet. In general, it will greatly enlarge the potential market by allowing for larger installations on behalf of larger organizations.
IT: What are the main differences between v1 and v2?
AC: Version 2 has a very enhanced addressing capability based on a very enhanced set of verbs defined in its RAS v2 protocol. H.323 v2 has mechanisms to provide high availability and fault tolerant operation, like support for backup Gatekeepers, and backup clients (end points). H.323 v2 also defines a full security framework to enable equipment vendors to support security functions like authentication, authorization, and non-repudiation, in addition to call privacy. H.323 v2 supports a much (7:1) faster call setup time than provided by H.323 v1.
IT: What was VocalTec’s role in all of this?
AC: Some of the above features were initiated and driven by VocalTec. The H.323 v2 Gatekeeper basically contains elements from our existing addressing technology called CMA. The provisioning for fault tolerant operation, was one of the first elements that VocalTec contributed to the H.323 v2 standard.
IT: What is VocalTec’s position towards the new standard?
AC: As a company entirely dedicated to IP telephony, VocalTec believes that the implementation of the H.323 v2 features — especially on the Gatekeeper side — is essential in making IP telephony a large-scale, successful telecommunications tool.
IT: What was done to improve call quality?
AC: On top of the reduction of the call setup time, H.323 v2 is capable of supporting the IETF standard for RTP redundancy, which is a mechanism that enables the transmitter to add redundant information to help the receiver reconstruct lost packets. This mechanism has important economical aspects because it enables IP telephony to work on non-well-behaved but inexpensive networks like the public Internet, and still provide good audio quality. The new H.323 v2 also supports IETF protocols like RSVP (Resource ReSerVation Protocol) which will enable the system to request certain guarantees from the network. This will ensure a guaranteed level of service from an IP telephony network.
IT: Can IP telephony become a viable replacement for traditional telephony?
AC: Certainly. With the above capabilities and the economics of using a unified network for voice and data, and the low price of connection, driven by the large number of IP linked devices (any PC on a LAN/WAN/Internet), provides a very viable replacement. In addition, the extended capability exchange and capability negotiation elements of the H.323 standard enable existing and installed IP telephony networks and platforms to gradually be upgraded, in order to provide much higher audio quality than available today in any phone system. The use of an IP network as a base for future telephony enables the implementation of easy-to-use, new and exciting services, ranging from Web-based applications to much enhanced intelligent network services.

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