Videophone tested over IP cable network

A videophone system supplier and a broadband cable manufacturer have transmitted what they say is the first point-to-point videophone call on an Internet protocol network over a coaxial cable backbone.

The demonstration linked two ViaIP Internet videophones from 8x8 Inc., Santa Clara, Calif., through IP-enabled cable modems from Com21's ComUnity Access line. The call was transmitted through a Com21 headend switch at 384 kb/s, although the system can go faster or slower. It delivered a picture quality of 352 x 288 pixels, refreshing the image 30 frames per second.

"That's the quality of VHS tape," said an 8x8 spokesman.

The H.323-compliant ViaIP videophone prototype puts a video camera in a set-top box and displays its image on any cable-ready TV. A touch-tone phone provides audio, dialing and navigation of the system's on-screen controls. The system includes a built-in 10BaseT Ethernet interface to link directly to a cable modem, digital subscriber line modem or corporate network.

Coaxial cable represents a promising transmission mode for provisioning residential IP telephony without running ISDN lines into homes. Many large cable operators already are upgrading coaxial lines to provide digital TV and Internet access.

"Broadband Internet access services are producing more than enough revenue to cover cable operators' costs, and subscribers are happy enough with the IP offerings that they're staying signed on," the 8x8 spokesman said. "For operators, that's a prescription for good business. The broadband public network being put in place by the cable companies-and soon by AT&T, Sprint, Qwest, Level 3 and others-will let us deliver what customers want: TV-quality video."

But the market for a cable videophone IP product has yet to be built, said Albert Lill, a telecom analyst with The Gartner Group, Stamford, Conn. "The cable industry will not be ready to roll out IP telephony for several years, " he said. "However, if you are a contender to provide the guts inside, now is the time to start so that you can produce a win when it's needed."