April 2002

ConvergeNet is one of the more exciting attractions that can be found at every Internet Telephony Conference & EXPO�. Essentially, ConvergeNet is a live, on-site network serving as a multi-vendor interoperability proving ground, serving as a proof-of-concept environment on the exhibit floor.

On February 6-8, 2002, ConvergeNet made yet another successful appearance at the Internet Telephony Conference & EXPO�, held at Miami�s famed Hotel Inter-Continental. About 25 percent of the exhibitors at the conference participated, led by event sponsor Mockingbird Networks. Other key participants included VoIP Group, Congruency, Pingtel, and Wombo.

Huge Crowd Delays Start
With almost double the expected attendance on the first day of the show, ConvergeNet took a back seat to keeping booths fully staffed. Even the engineers who were brought to the show specifically to participate in ConvergeNet were asked to man booths and help manage the capacity crowds. However by one o�clock that afternoon, the engineers had all made their way to the ConvergeNet booth to start their testing.

Day 1
It was decided that the Mockingbird Impresaria ESS (which includes a softswitch, SIP server, H.323 Gateway, and a SIP-H.323 protocol translator) would act as the hub of the network. Not only would this make for a better demonstration, but it was also technically necessary, since no two IP telephones on the floor were capable of communicating directly due to protocol and codec support issues. The Congruency i.Picasso 6000 supports H.323 and the G.729 codec. The Pingtel expressa supports SIP and the G.711 codec. The VoIP Group�s gateway supports H.323 and both the G.729 and G.711 codecs. The plan was to have the Mockingbird softswitch facilitate the communication between these non-interoperable devices.

The first scenario was to move calls between the Congruency i.Picasso 6000 and the Pingtel expressa. This would be accomplished by having calls start at the Congruency i.Picasso 6000, move to the Congruency CNS 3200 Enhanced Hosted Communications Platform, over to the Mockingbird Impresaria ESS and then to the Pingtel expressa telephone. All of the signaling was made successfully, as the Mockingbird Impresaria ESS properly translated the H.323 signaling to SIP signaling. However, the calls were rejected by Pingtel�s expressa telephones due to a codec mismatch. There was no device that was part of the ConvergeNet that could transcode the G.729 supported by Congruency to the G.7.11 supported by Pingtel.

Calls going in the opposite direction, from the Pingtel expressa to the i.Picasso 6000 were also rejected due to the same codec mismatch.

Day 2
On the second day, we attempted calls from the Pingtel expressa to the PSTN. This would be accomplished by having calls start at the Pingtel expressa, move to the Mockingbird Impresaria ESS, over to The VoIP Group�s VcomX Gateway and then out into the public network. After a number of hours of trying, the call could not make it out into the public network. It was determined that the problem was in the Faststart procedure within the H.323 signaling protocol. Faststart is part of the Impresaria ESS, but is not implemented on the VcomX Gateway.

Interoperability Is Still An Issue
After successful interoperability events in the past, we were ready to declare interoperability a �dead Issue.� We figured that the technical issues had been solved and that it was high time for the vendors to move on towards created applications, billing systems, and OSS that could work within a converged network. However, it now seems that the upheaval within our industry (with many �Early Entrants� now resigned to the telecom dust heap of history) has caused a momentary backward step in the area of interoperability. Some new entrants into the space are once again supporting proprietary signaling protocols and codecs, or they are fighting protocol and codec wars, choosing to support one over the other, rather than building a flexible product that can work in many environments under many conditions. We hope that by the next installment of ConvergeNet, at Internet Telephony Conference and EXPO � October 1�3 in San Diego � equipment and software manufacturers will have moved beyond these issues so that we can once again begin looking at interesting applications and other required back-office systems that are required for the commercial implementation of converged networks.

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