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The Ultimate VoIP Solution: Page 3 of 6


By now it's become a mantra: The Session Initiation Protocol (SIP) is the future of VoIP. The vendors are saying it, and the network designers are building for it. Even Cisco Systems, the only major VoIP vendor not to offer native SIP client support, will add the capability to its next major release of Cisco Call Manager expected at the end of the year. All this begs the question, just what should network architects be considering when they evaluate an IP PBX?

To answer that question, we assembled a panel of leading VoIP architects and designers and asked them to compose a wish list of ideal telephony requirements (see "The Incredible Panel"). Together, the group mapped out exactly what the Incredible VoIP Architecture should look like. They defined the core of the SIP network--the call-stateful proxy--and prescribed the resiliency, scalability, and E-911 features that such a proxy should deliver. The panel also took into account the remote office, defining an integrated device that provides both remotely managed VoIP and the right mix of security functions. No VoIP solution would be complete without effective management, of course. The panel's ideal VoIP management solution not only integrates with the existing management infrastructure, but allows network architects to define global policies for the telecom network, as well as specify configurations for particular call servers.

As for the Incredible Telephone, our team eschewed the large color displays of high-end models where videoconferecing was concerned. "You don't get anything useful in interactive communications with a 4x7-inch display. You just get an expensive toy," says Brian Rosen, one of our panel experts. (Using the display for phone-based applications is another matter, however.) Our panel also wanted SIP phone sets that didn't use proprietary SIP extensions. Those phones should be able to fail over to a backup power supply or an alternative SIP proxy and offer better-than-PSTN voice quality.

In all, the Incredible VoIP Solution borrows elements from many of today's VoIP systems and mixes them with some features and functions not yet seen. The solution's fully distributed design can be seen on a smaller scale in ShoreTel's VoIP architecture, while the notion of a stateful SIP proxy capable of supporting tens of thousands of IP or analog endpoints is more reminiscent of Siemen's HiPath 7000 or Zultys Technologies' Enterprise Media Exchange server. In terms of diagnostic functions, many of these capabilities can be found in advanced management platforms such as that from Avaya. The emphasis on a single remote device at the remote office falls in line with Cisco's Integrated Services Router line, while Mitel Networks' 5230 IP Phone is probably the closest to the Incredible Telephone.