Nortel and Cisco squared off in a presidential-style debate at VoiceCon today, each defending its own approach for VoIP.

Nortel is a traditional voice switch vendor, with products based on circuit-switched technologies, referred to as Time Division Multiplexing. But it also has products that adapt these traditional networks to IP. Cisco, meanwhile, sells pure IP products to handle voice, treating it as just another data stream.

A number of vendors fall into the Nortel camp, including Avaya and Alcatel, while Cisco's direction is joined in the U.S. by just 3Com and several smaller players.

Tuesday's debate attracted a large audience by VoiceCon standards, with more than 2,500 people, mostly IT managers, in attendance for the second day of the event. Many of them hooted, howled and applauded loudly in response to positions taken by each side.

Cisco's representative, Michael Frendo, vice president of voice systems engineering, fired the first shot, likening the Nortel-style technologies to driving a car with a horse tied to the rear -- just in case the car fails.

"Can I drive 50 mph with my horse tied behind me?" he asked, to laughter.

Philip Edholm, CTO of enterprise solutions at Nortel, won a loud audience response, too, with a reference to singer Janet Jackson's "wardrobe malfunction." "Did anybody see the (Super Bowl) halftime show? That shows it's not a question of what you can do, but what you should do."

As far as updating voice networks, Edholm acknowledged that a company can go with a pure IP system, but he questioned whether it should. He said a long list of Cisco customers have installed Cisco IP voice capability only to back off, including Merrill Lynch.

Frendo fired back, claiming that only a handful of customers did so -- not because they didn't like Cisco's products but because they wanted a different architecture.

In the well-publicized Merrill Lynch case, a senior official at the brokerage who asked not to be named told Computerworld last year that it did away with the Cisco system because it didn't want to lose voice capabilities at a New Jersey office if its data network crashed.

Edholm also contended that Cisco's approach to VoIP seems to omit the idea of a "softphone," which relies on the computer to make calls and does away with the need for a handset. With such an approach, a user can simply click on an icon on a screen to place a call, without needing a phone number or even a person's name.

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