April 2001

BY ADAM ALTMAN

For a long time now, I've been hearing the words "protocol" and "standard" used interchangeably in the Internet telephony industry. While they are similar terms, there is a major difference that is notable when discussing interoperability, mainly because a big part of the effort is finding a common standard to replace or work with the current protocols present. H.323, SIP, MGCP, Megaco, etc., are protocols -- they govern the format of voice calls over IP. However, they should not technically be called standards since none of these are agreed on by everyone involved, not even within each individual protocol. At most, these protocols could be considered "open" standards, but this terminology just confuses matters. Likewise, compression codecs, such as G.711 and G.729 also get confused into the mix when they should only be considered a part of the overall configuration, and should therefore not be considered as either a standard or a protocol. Differentiating all of this may seem like so much "nitpicking," but it does show an example of the confusion surrounding interoperability in general, so making these sorts of distinctions may help clear up some communication issues.

In my last ConvergeNET recap ("Satisfying An Urge To Converge," INTERNET TELEPHONY magazine, December 2000), I discussed the four C's for VoIP interoperability: Commitment, communication, constitution, and convergence. The above example embodies the importance of the communication aspect. General communication between companies participating in the fifth installment of ConvergeNET at INTERNET TELEPHONY Conference & EXPO in Miami from February 7-�9, 2001 was extremely important even before the actual demonstrations began, as were the other C's.

We arrived organized with pre-planned diagrams ready and IP addresses assigned with plenty of time to spare before the show. Heading the H.323 side of ConvergeNET was NetCentrex. With the invaluable help of Science Dynamics and Quintum Technologies, two zones were set up for the test network using NetCentrex's gatekeeper and Quintum's Tenor Gateway, which can act both as a gatekeeper and as a gateway. It was the commitment from these three companies and the constitution to achieve these interoperability tasks that drove ConvergeNET on the H.323 side. While apparent at past ConvergeNETs, this commitment was overwhelmingly evident at this show. It dictated achieving successful convergence on virtually every demonstration attempted. I personally thank them, as should anyone that realizes just how important interoperability is for Internet telephony. (While on the subject, I would also like to thank Way2Call Communications (formerly Shelcad) for their commitment to each and every ConvergeNET thus far.)

Figure 1 shows the H.323 test network for ConvergeNET, which is pretty self-explanatory. Science Dynamics made VoIP calls with everyone on that list: NetCentrex, Quintum, Way2Call, ZMM Technologies, and Addatel. I personally made a few of these VoIP calls and determined that the quality of the calls was generally agreeable to my somewhat discerning ear. Science Dynamics was even able to converge using additional equipment from Quicknet Technologies.

With the exception of Quintum, NetCentrex also registered and converged with all of these companies. Unfortunately, NetCentrex and Quintum could not interoperate between their gatekeepers before the EXPO ended. However, both companies noted how much they learned during the process. I cannot stress enough about the importance of this education.

Before the show was done, Science Dynamics attempted to link with ASC Billing Solutions through their RADIUS servers and then make a VoIP call through NetCentrex's gatekeeper. This type of demonstration was first advocated by Digiquant (formerly Belle Systems) at the previous ConvergeNET in San Diego and came closer to being realized in Miami. They were able to link their RADIUS servers but the configuration for making the actual VoIP calls could not be correctly determined before the show ended. However, I certainly commend the attempt and look forward to this demonstration being successful at the sixth Installment of ConvergeNET at October's INTERNET TELEPHONY Conference & EXPO in San Diego.

On the SIP front, Ubiquity Software headed the charge and showed many of these demonstrations through their SIP Center. As depicted in the SIP diagram, Ubiquity used endpoint equipment from Cisco (both their IP phone and Komodo Fone), Pingtel, and 3Com as well as their own SIP user agent and Helmsman Desktop software to connect through the virtual test bed at www.sipcenter.com to another endpoint. With the exception of the Cisco IP phone, these VoIP calls were all successful. For example, a 3Com SIP phone successfully called both a Komodo Fone and a Pingtel xpressa phone through Ubiquity's SIP proxy server. Unfortunately, testing could not take place using the Cisco IP phone because the correct power adapter required was not available at the show.

In addition, Ubiquity was also able to converge with Indigo Software in the traditional ConvergeNET manner. They successfully called each other from booth to booth across the LAN on the Internet Telephony EXPO Exhibit Hall floor.

Thus ends another ConvergeNET as we stride closer to attaining interoperability and a de-facto standard. We are slowly zeroing in on our goals, and the next installment of ConvergeNET in San Diego should further attest to that commitment that we initially laid on the table almost a year and a half ago. As we pave the road towards better communication while continuing to educate attendees and vendors about interoperability issues, I wonder when I should attempt to clarify all the acronyms meandering around the industry. But alas, that's for another time, so for now, I'm content with taking a "stand" on matters in the realm of interoperability. 

[ Return To The April 2001 Table Of Contents ]