Cable Telephony: to IP, or Not to IP

Cable operators have been looking forward to the day Internet Protocol (IP) telephone technology becomes good enough to ensure a nearly flawless level of service.

Its getting close, but not close enough.

Cable operators have been looking forward to the day Internet Protocol (IP) telephone technology becomes good enough to ensure a nearly flawless level of service. But that day is not today.

"IP telephony is not at the point where its deployable as a commercially viable service," says Michael Goodman, a senior analyst at The Yankee Group.

Voice-over-IP puts voice signals into digital packets similar to the ones that carry data over the Internet. As digitized voice packets, voice communications can then run over data networks and integrate with data and digital video. VoIP lets cable operators use one network to handle all their TV, video, data and voice services.

And cable operators are keen on this cost-effective way to offer telephone services. They know that voice calling is one app that customers will use.

But, Goodman says, no cable operator yet has a VoIP system in place, though the technology will be ready for deployment in one to two years.

A few cable operators are selling telephone service, but they use standard circuit-switched networks — the common technology for analog phone systems run by the regional Bells, long-distance companies and others.

Dallas Clement, a senior vice president of strategy and development at Cox Communications, says his company started its circuit-switched voice service more than four years ago. He says that Cox now has 300,000 telephone customers.

"If we were entering it today, we might make different choices," Clement says. "But all in all, its a service were glad we got into."

Cox charges an average of $50 per month for its primary line service, including local phone calls, long-distance access and extra features such as voice-mail.

AT&T Broadband offers cable telephony using circuit-switched networks, but even this company with its experience in telephone services is pushing to develop IP voice technology. "VoIP for them is priority one, two and three," Goodman says.

Andrew Johnson, AT&T Broadbands vice president of communications, says IP telephony will prove much less costly to expand than a circuit-switched system.

Nevertheless, Johnson says, cable operators offering circuit-switched telephone service can put the heat on telephone operators. AT&T Broadband offers less robust "second line" phone service for $5 per month, and top-quality "primary line" service with basic features for about $33 per month.

Cox and AT&T Broadband are exceptions. Goodman says that most cable operators will stay out of the telephony business until VoIP technology matures. Few can afford to create a separate infrastructure and then toss it out in a few years.

Cable Television Laboratories, the research consortium for the cable TV industry, is now testing the technology standards that will support IP telephony service over coaxial cable connections.

Maria Stachelek, director of business development and standards for CableLabs PacketCable research, says operators are now waiting for networking gear that will support Data Over Cable Service Interface Specification 1.1. DOCSIS 1.0 is the standard for building the current crop of cable modems.

DOCSIS 1.1 addresses issues crucial to IP telephony service, such as prioritizing voice packets, call signaling management, security, device provisioning and event message collection for billing facilitation.

Stachelek says DOCSIS 1.1 also provides features that will allow cable operators to guarantee the quality of service of an IP voice call. She says cable operators have expressed much interest in IP telephony, and DOCSIS 1.1 is specifically designed to address this interest, though it also helps cable operators offer other multimedia data service such as videoconferencing.

CableLabs is testing gear for DOCSIS 1.1 compliance, which will likely be available later this year, Stachelek says. Cable operators can build an IP telephony network without DOCSIS-compliant gear, but until now there have only been "bits and pieces" of equipment on the market to support high-quality IP telephony.