Comcast Corp. has discovered that Internet-protocol
telephony might be an option sooner than many observers thought possible, while at the
same time, AT&T Corp. is discovering that the traditional cable-phone approach is
gaining ground as a cost-effective option.
The developments -- involving a test at Comcast's Union,
N.J., system and ongoing commercial deployments of voice service by AT&T Broadband
& Internet Services -- point to the likelihood that MSOs face a more favorable set of
working conditions in offering voice services than they have had to date.
Comcast's trial takes advantage of new voice-over-IP
specifications developed through Cable Television Laboratories Inc.'s PacketCable process
to deliver multiple lines of toll-quality service, complete with all of the features
consumers expect, said Mark Coblitz, vice president of strategic planning at Comcast and
chairman of the PacketCable group.
"Most of the discussion around cable telephony over IP
has focused on the belief that this technology could not deliver the reliability, voice
quality and number of services to satisfy customers' demands right now," Coblitz
said. "Our experience shows otherwise."
But the trial is only in a first stage involving 25 users,
which means that the integrated-access equipment supplied by Lucent Technologies will have
to scale to thousands of users and deliver the same level of quality before Comcast can
move to commercial deployments.
In addition, the customer-premises MTAs
(multimedia-terminal adapters) and headend CMTS (cable-modem-termination systems) Motorola
Inc. is supplying as part of Lucent's "CableConnect Solutions" system must meet
the specs set for version 1.1 of DOCSIS (Data Over Cable Service Interface Specification)
before wide-scale deployments will be possible.
Lucent is confident that all of the pieces will fall
together to support the commercial rollout of PacketCable-compliant IP-telephony services
on a wide scale by the second half of next year, said Dee Dee Nye, vice president of the
vendor's cable-communications group. "You can be sure that IP telephony will be ready
for deployment in that time frame," she said.
Comcast isn't the only MSO testing Lucent's system, Nye
added. "We've been pretty quiet about what we're doing, but we think we have an
integrated solution that is resonating with our target market."
That solution begins with the "PathStar" access
server, which combines the functions of several products into one module, including the
routing/switching process, the IP-voice gateway interface with the public switched
telephone network, call-control and intelligent-network feature provisioning and
These access servers can be positioned at the headend and
at the distribution hubs in arrays supporting up to 100,000 customers, noted Harrison
Miles, director of technical marketing and solutions management within Lucent's cable
"The system is designed so that you can start out at
the headend with a single data shelf supporting up to 40,000 customers, and then add units
at the distribution hubs as your penetration expands," Miles said.
The system is designed specifically for the cable
environment, where MSOs will begin offering IP telephony at the local distribution level
while interfacing with circuit-switched or asynchronous-transfer-mode backbones to connect
with networks outside of the local cable "cloud," he added.
But MSOs will move quickly to an all-IP end-to-end
paradigm, interconnecting with other PacketCable-compliant local IP-telephony networks,
once terabit routers such as what Lucent's newly acquired Nexabit Networks subsidiary is
developing are deployed, Miles said.
Once that happens, operators will need equipment at the
local distribution level that is interoperable with all PacketCable-compliant gear --
requiring conformity with version 1.1 of PacketCable, now slated for release sometime in
"Version 1.0 [of PacketCable, soon to be released
publicly] doesn't solve the zone-to-zone interoperability requirement," CableLabs
vice president for broadband services and technology David Bukovinsky said. "We'll be
addressing that along with some other things, like IP-address privacy, in 1.1."
Posing a stiffer challenge than compliance with
PacketCable, vendor compliance with DOCSIS 1.1 -- which adds quality-of-service control
capabilities to cable modems -- is essential to getting IP-voice services off the ground,
Bukovinsky noted. "Based on what we've seen so far, there's been considerable
progress on hardware [for 1.1 compliance], but the software has a long way to go," he
Backed by surging MSO demand for IP-voice solutions,
CableLabs is doing everything in its power to push vendors along in the
software-development process, Bukovinsky added. But it remains to be seen whether they'll
be ready when certification tests are slated to begin in March, he said.
Meanwhile, AT&T Broadband is gaining confidence in the
non-IP "constant-bit-rate" approach to delivering voice over cable networks,
chief technology officer Tony Werner said. "We're getting really good results in the
marketplace, and the cost model is improving significantly," he said.
Where the total per-customer cost of provisioning voice has
been about $890 at the outset of the company's first deployment in Fremont, Calif., Werner
expects the price to fall to about $590 by the third quarter of next year. "We're
seeing more vendors, including Lucent and Motorola, coming into this space, which will
have an impact on the costs," he said.
By the second half of next year, the cost drops will put
the four-line constant-bit-rate cable option at close to parity with the IP option where
voice services are concerned, Werner noted. But IP voice represents "one more bite
out of the apple" costwise, because the network-interface units supporting IP voice
also support high-speed data. This eliminates the cost of the separate modem required for
current voice customers who want high-speed data, as well.
Werner said it was likely that Bell Laboratories would be
bringing new developments to light on the IP front in the near future. But these concepts
are tied to architectural configurations that go beyond the current version of
PacketCable, meaning that they'll take longer to bring into commercial implementation.
Meanwhile, the performance and cost curves of the non-IP
option are encouraging AT&T to stick with this approach on an aggressive rollout
schedule, Werner noted. Vendors are preparing product that will make it easy to transition
to IP from the existing platform at the headend and customer premises by simply replacing
existing line cards with DOCSIS cards, he added.