COMCAST'S IP VOICE TRIAL SIGNALS TECHNOLOGY SHIFT

Self-avowed IP proponent now has switches to burn

In Detroit and its suburbs, Comcast is nearing the end of a voice-over-IP trial that deploys IP in a migratory fashion. The trial represents a departure for the Philadelphia-based multiple systems operator, which has been spearheading cable's VoIP efforts in an attempt to circumvent switched networks. It also could provide important technological information for Comcast when it comes time to migrate AT&T's 1 million-plus circuit-switched customers after the two companies merge later this year.

The trial — which used Arris' cable modem termination system (CMTS), Motorola cable modems and Tollbridge Technologies' GR-303 gateway — started before merger plans between the operators were solidified, a company executive said.

“I've always been against [Telcordia's GR-303 standard] because I didn't want to go out and buy a switch if I didn't already have one,” said Steve Craddock, Comcast's senior vice president of new media development.

Comcast inherited the Detroit switch, which was originally bought by the former MediaOne. The Lucent 5ESS came with about 20,000 telephone subscribers and the capability to handle an additional 80,000 users. Comcast also acquired a MediaOne switch in Alexandria, Va.

The MSO is using Detroit as a proving ground for the migration from circuit-switched to IP technologies, Craddock said.

Because the switch was using only about 20% of its capacity, selecting a few hundred new subscribers for the IP trial was relatively easy. More difficult was getting the correct hardware, Craddock said.

“You needed three components to do this: a CMTS that would work; a modem that provided DOCSIS compatibility and dial tone, and a GR-303 gateway,” Craddock said.

Unlike the more traditional circuit-to-packet deployment, Tollbridge's gateway is being used to take IP connections from the CMTS and turn them into circuit-switched connections that can terminate on the switch.

The trial, which is nearing its conclusion, is providing Comcast with a plethora of information on the operation of the IP network and how it compares with the more conventional switched network, said Tim Collins, vice president of telephony for Comcast's Midwest division.

“We get to see this in operation side-by-side with communities that have our circuit-switched products. We get feedback from them and response in terms of how it works from their perspective and whether they perceive any differences,” he said.

The trial may be a one-time event, though, given Comcast's leadership in CableLabs' PacketCable VoIP specifications effort. It also could be a proving ground for future migratory telephony efforts. Craddock was cautious about drawing too many conclusions from the trial and how it relates to Comcast's plans for AT&T Broadband's switched telephony customers.

For one thing, the size of the Detroit trial permits “swivel chair” provisioning, using one system to provision cable modems and another for the switch. AT&T's larger installed base would preclude that.

“For now, we're just trying this in Detroit to see what happens,” Craddock said.

Tollbridge is also looking ahead. In addition to migrating from circuit switches to IP networks, it's learned how reprogram its gateway into more of a softswitch role.

Replacing the Class 5 switch is one direction the technology will move, said Kevin Woods, vice president of marketing for Tollbridge. “The other direction that it goes in, and probably a longer term development for us, is to be able to migrate circuit switched customers onto the softswitch.”