Sounding Board: Complexities Snag Cable VoIP Agenda

There's more need than ever for a voice-over-IP solution in the cable industry, but it looks like cable operators may have to wait longer than they had hoped would be necessary before standardized solutions become commercially available.

VoIP on cable, as embodied in the PacketCable specifications developed at Cable Television Laboratories, has emerged as a front-burner item for companies that have been waiting on VoIP to launch voice services and for those who are applying or plan to apply circuit-based cablephone technology to support what is turning out to be a thriving new business. New thinking within the latter group points to use of the PacketCable platform in a hybrid approach that taps the scalability and feature-rich capabilities of the mature circuit-based system while exploiting the bandwidth and operations efficiencies of IP over the distribution portion of the cable network.

Unfortunately, however, it won't be possible to proceed with a hybrid approach that is PacketCable compliant anytime soon, because CableLabs is finding the complexities of the platform are making certification of standard- compliant vendor hardware and software extremely difficult. "People really want to move forward at this point, even those who are using circuit switches to support established voice operations," says an executive at one of the vendors participating in the testing process, who spoke on background. "It's frustrating to everyone concerned that they're not ready to begin certifying product."

In an attempt to clear remaining hurdles blocking progress toward certification of vendors under the PacketCable standard, CableLabs was about to begin a round of interoperability testing at press time that marks a significant departure from the precertification tests it's been conducting. A source close to the process says CableLabs had been conducting what amounts to precertification trial runs and that another one had been scheduled to begin for the third quarter when the decision was made to go another route.

"Based on our need to better understand the differences among vendor interpretations of the standard and how that affects the way their products interact, we've decided to have a big open interoperability event as the next step in preparations for future certification waves," the source says. The aim is to determine to what extent various products interoperate with each other so as to help decide which interpretations of the various profiles under the PacketCable umbrella should be locked in as the ones for everyone to follow, he adds.

Varying vendor interpretations of specifications are commonplace in the standards-setting process across all categories of telecom and cable platforms, but PacketCable is especially difficult because there are so many components in the chain. For example, a media terminal adapter (MTA) must interface with subscribers' modems, the call management server, the cable modem termination system, the system OSS and various servers that deliver certain applications such as security. All of these interfaces must be tested against a variety of signaling and other applications, and all the connected components in the test of an MTA product's compliance must themselves be compliant.

These complexities promise to continue to challenge CableLabs engineers' ability to structure a final certification process. "We're doing our best to get to an official certification wave this year, but we're not making any predictions," the source says.

Meanwhile, pressure is building as virtually all cable entities involved in voice or contemplating voice launches seek to take advantage of what they see as huge benefits of PacketCable technology, including those that plan to use circuit switches. For example, Comcast Corp., which before moving to acquire AT&T Broadband had been contemplating a pure PacketCable play, is testing a telephony solution supplied by Cedar Point Communications that combines access to Class 5 switch features with the PacketCable platform. Comcast president Brian Roberts says the combination of PacketCable and circuit-switched technologies could produce major gains for the industry.

"The real question for our company and our industry is, as telephony goes digital, how do you transition from a circuit to digital IP network?" Roberts says. "We're having some exciting experiences in our Detroit system" in demonstrating how that might be done.

Comcast inherited a base of 15,000 voice customers, now 25,000 voice customers, when it acquired the Detroit area system from AT&T Broadband. Like all AT&T Broadband voice-over-cable services, the system uses a circuit switch. But in the test there's an IP component as well, Roberts notes. "The capital spending is 50 percent reduced because in the middle of the phone call we're experimenting with IP while leaving circuit in the house and circuit in the headend back to the long-distance company or back to the public switched network," he explains.

The good news for companies pursuing the circuit-switched model is that waiting for PacketCable will not affect their ability to generate much-needed new revenue from voice services. But for all the cable companies that are counting on generating voice revenue without having to pay for Class 5 switches, the squeeze on anticipated growth makes the PacketCable frustration a bottom line issue of major consequence. Whether and how far the squeeze extends into next year is now anybody's guess.

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