The last laugh: Com21 unveils upstream multiplexer, plans for IP telephony

Describing the fortunes of Com21 over the last few years as a roller coaster would be a little too easy. Initially targeting cable operators entering telephony, the company was at the forefront of an emerging market, only to watch the market crash as the industry refocused on core video businesses.

But in the next few years, don't be surprised to see the Milpitas, Calif., company's name pop up again as cable operators re-evaluate the market in light of developments around Internet telephony technology. At next month's National Cable Television Association show, Com21 will unveil what Vice President of Marketing Buck Gee calls a "high-speed RF switch."

The Remote Path Multiplexer, working with Com21's Com-Controller headend receiver, reduces the problem of noise funneling in hybrid fiber/coax networks.

Funneling occurs on the reverse path when noise is combined on several paths. Because of this, most cable modem headend systems are designed to handle a limited number of upstream paths. The result is that cable operators often must target neighborhoods and begin generating revenue before they can move to a widescale rollout.

The RPM funnels several upstream paths into a single channel. Intelligent multiplexing within the unit transmits only signals from one return path into the headend unit's receiver. The result is that each ComController unit can handle up to 96 reverse paths.

"This is going to speed cable modem rollouts across large metropolitan areas," said Gee.

More important, the multiplexer is just one more step in Com21's plan to provide an integrated voice/data product to cable operators. "It's always been our view that voice, data and video will be delivered over the same cable," said Gee.

At the heart of that system is an asynchronous transfer mode architecture that will allow cable operators to provide multiple tiers of data service as well as guaranteed bandwidth for telephony.

Although not fully deployed with voice, Com21 already has shipped more than 200 systems. One of the largest deployments to date has been with Halifax Cable, which has deployed the modems in systems passing 65,000 homes.

Halifax evaluated systems from Bay Networks' LANCity division, Zenith, Terayon and Motorola before choosing Com21's system, according to Jeff Campbell, manager of data services for Halifax.

"We like the flexibility and that they are small and focused," Campbell said. He cited the system's ability to provision constant bit rate (CBR) services. Since introducing five tiers of business data service late last year, the company has signed about 50 accounts. "The Com21 system has allowed us to act like a bridge and get people on a different system," said Campbell. "The other thing the CBR does is that it positions us to offer IP telephony."

Among the service tiers, all of which are symmetrical, Halifax offers increments of 64 kb/s up to a T-1 type service. Com21's system could allow other levels, but the company must be aware of the competition, said Campbell.

"We are looking at expanding that, but right now the market is still very young and people are basing their decision on what's available in the telco world," he said.

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