Boulder, Colo.— Comcast Corp. has switched on 75 "friendly" homes for its voice-over-Internet protocol (VoIP) telephone-service trial in Philadelphia's western suburbs.
The MSO also plans to add as many as 500 other test homes in April, as it expands by linking five headends within a regional fiber ring serving 180,000 households. The increased reach will allow Comcast to experiment with various mix-and-match bundled elements in its VoIP test.
The update on Comcast's VoIP trial came from cable unit vice president of VoIP Sam Chernak at a March 11 Cable Television Laboratories Inc. media briefing here.
The operator inherited 1.4 million circuit-switched telephony subscribers from AT&T Broadband, but doesn't plan to expand that base either in current or new markets. It will rather focus on improving the former AT&T systems' other offerings, including analog and digital video services.
Once VoIP technology is ready for extensive deployment, it will be a more cost-effective means for cable operators to deploy voice services, Comcast executives said.
Comcast at that point would be able to integrate elements of VoIP into those cable systems with legacy circuit-switch gear and transition those customers to an IP platform.
At the moment, Comcast has built an overlay network to launch VoIP in Coatesville, Pa., and surrounding towns. The dynamic quality-of-service levels needed to launch VoIP on the existing data infrastructure are not quite ready, thus the need for a separate network, Chernak said.
In Coatesville, Comcast installed a separate Data Over Cable System Service Interface Specification 1.1-based cable-modem termination system to handle the VoIP telephone calls, alongside an existing DOCSIS 1.0 CMTS to steer data traffic.
Calls are processed from the home through a multimedia terminal adapter, then transmitted via the cable plant to the DOCSIS 1.1 CMTS.
From there, phone calls travel through the soft switch and gateway to the public switched telephone network.
Once quality-of-service issues are cleared up — hopefully this year, Chernak said — Comcast will be able to run data and telephony within the same plant, saving money and making VoIP more cost effective.
"You get efficiencies when you have integrated high-speed-data and voice plant and find reasonable ways to allocate costs," Chernak said. "When you have one MTA and a common CMTS and you figure out a way to allocate cost, you get good economics."
Comcast plans to use its existing data billing system to handle VoIP.
"We believe such integration will be compelling in the overall economics of a cable telephone business," he said.
The key for Comcast is to layer VoIP onto its existing data plant with very little incremental cost, said Chernak. When dynamic quality-of-service can be layered onto existing CMTSs, "that's when we see very compelling economics."
Comcast is using eight vendors in the initial test, said Chernak.
Once the headend fiber ring is activated in the next month, "we'll look at bundled solutions," Chernak said.
While those solutions might not be completely PacketCable-compliant, Chernak said it was important to strike a balance on costs to keep VoIP economical.
The trial is powered by eight-hour batteries in the MTAs, but Comcast plans to install lithium ion batteries by year's end, he said.
"We'll be looking to expand the ring in summer," Chernak said. "Then we will be able to trial other architectures."
Some of that new testing is underway within Comcast's labs in southern New Jersey, he said.
"The five headends gives us latitude to test a bunch of things," he said. "The key is to get the network out there to cover a responsible amount of people if forces act upon us to act more aggressive [with VoIP]."