Washington -- The cable industry's PacketCable team
hopes to complete specifications for products capable of supporting mass deployment of
primary-line telephone service by year-end.
The goal: mass deployment of Internet-protocol telephony
service within two years.
"We're going to produce a technical spec by just
about year's end that will encompass all of the things that we think this thing needs
to have in it to be the kind of product that we're looking for," said Steve
Craddock, vice president for new-media development at Comcast Corp. and chairman of the
PacketCable business committee.
"We're going to run a technical trial starting
next year and turn that into a market trial," Craddock added. "Our view is to
have a real product, mass-deployable, by about 20 months from now."
The latest word on the progress of the
telecommunications-over-IP initiative -- including much fuller discussion of technical
particulars than had been offered previously -- came last week, at the Voice on the Net
Craddock and staff members of Cable Television Laboratories
Inc. who are working on the PacketCable initiative made it clear that they are targeting
as a first priority a voice-over-IP service that is on a par with, if not superior to,
primary-line service from the telephone companies.
Cable-IP-voice capability "has to support primary-line
service, which represents somewhat of a change in direction for some of us," Craddock
Some operators had felt that the benchmark for an
IP-cable-telephony standard should be somewhat lower to fit the product needs of operators
that wanted to pursue second-line business strategies.
But the PacketCable group has come to realize that by the
time systems are ready for deployment, the ability to offer a first-line service will be
"absolutely necessary" to compete in the rapidly evolving
IP-based-telecommunications arena, Craddock said.
This means not only voice quality and latency on a par with
the public switched telephone network, but also: powering independent of the electric
company; compatibility with legacy fax machines and modems; and dialing patterns and user
instructions "just like the PSTN, or easier," Craddock said. "You have to
be able to dial anybody, anytime, anywhere," he added.
PSTN-quality service also requires offering a basic feature
set that at least matches what the telcos provide, noted Ed Miller, project director for
data-network architecture at CableLabs. These include call waiting, three-way calling and
features like caller ID, as well as the ability to provide multiple-line and single-line
This is a very tall order, given the state of IP-voice
technology today and the challenges that cable faces in ensuring that its data modems can
support the constant-bit-rate quality of service that is essential to delivering voice
But the PacketCable team is looking at ideas from various
vendors that suggest that the goal can be reached, assuming that vendors can be persuaded
to share their ideas in the interest of achieving interoperability, Craddock said.
The PacketCable group consists of Comcast, Time Warner
Cable, Rogers Cablesystems, Cox Communications Inc., Cogeco Cable and Le Groupe Videotron
Ltee. as lead MSOs, working with the rest of the industry through CableLabs.
It is focusing on key interface issues that are not the
primary focus of other IP-voice efforts -- which is to say, the access segment of the
This means that out of some 38 interfaces that CableLabs
has identified as important to achieving end-to-end IP-voice-networking capability, the
group is hoping to produce its own specs on eight that are essential to completing the
last-mile segment over cable, said David Bukovinsky, project director for software
architecture at CableLabs.
From a cable perspective, these are the interfaces over the
access network that must be agreed upon "in order to spin silicon," Bukovinsky
said, noting that these elements are in addition to already-selected physical and
media-access-control mechanisms that are part of the DOCSIS (Data Over Cable
Service/Interoperability Specification) modem initiative.
"The goal of PacketCable is to get these interfaces
standardized as fast as possible with the group of vendors that we're working with,
and to allow them to start building product," Bukovinsky said.
These interfaces address two types of client access to the
PacketCable network, he noted.
The mass-market end-user client is a device to be embedded
in DOCSIS modems, which will translate signals from standard telephones to IP packets and
put them out over the cable-data channel on the hybrid fiber-coaxial network.
The PacketCable group is looking at several emerging
client-interface standards for this interface, including IPDC (IP-device-control
protocol), SGCP (single-gateway-control protocol); and "H.323 Lite." All of
these represent efforts within the IP-voice community to enhance network operators'
ability to manage and add features within their operating "clouds" from
centralized control centers.
"As the OpenCable [set-top] project starts producing
product, we're also looking at incorporating this [PacketCable client] product into
the OpenCable boxes," Bukovinsky said. "There, we'll have the potential of
offering video telephony and essentially having a single device in the home that handles
all of these functions."
Craddock suggested that a video-telephony capability along
these lines would trail the introduction of mass-market cable-IP-voice services by
"15 to 20 months."
The second type of device that PacketCable is selecting
interfaces for is a "rich client with distributed control," such as a "SoHo
PBX" (small-office/home-office private-branch exchange), which will support
"multimedia-based feature sets" for users who are communicating through more
"We want to take advantage of some of the richer
signaling protocols and the more interesting client devices and software that's
starting to come out on the market," Bukovinsky said "We can charge a bit more
for services and give customers some innovative features that they could never picture
with a black telephone."
To accommodate cable linkage with these devices,
PacketCable is looking at version two and the still-emerging version three of the H.323
Internet-telephony standard, "as well as some of the extensions that standards bodies
are putting in," Bukovinsky said.
"And we're also looking at extensions ourselves
in certain areas to address needs that other participants in standards bodies have not
had, to date," he added.
Another key point of standardization for PacketCable is the
gateways that link cable-originated or cable-terminated calls to the PSTN and the
protocols used in connecting these with the central call-management controllers, or
"Initially, most of the calls will be terminated to
the PSTN until we achieve critical mass in the rollout of this, so we want to standardize
on the gateway architectures to help drive the costs down and to be able to work with
multiple vendors in our network," Bukovinsky said.
In all of this, he noted, cable is tracking with standards
bodies as they move toward separating the signaling interfaces from the media-translation
interfaces in the interest of bringing SS7 (signaling system 7) into their domain. SS7 is
the intelligent network that runs parallel with the PSTN to set up calls and provide
special capabilities, such as 800 numbering.
DOCSIS modems with certain extension capabilities beyond
the 1.0 version of the standard, often referred to as "DOCSIS 1.1," will be
essential to achieving voice service, said Andrew Sundelin, project engineer for
integrated-service technologies at CableLabs.
The PacketCable group has settled on a real-time polling
technique as a means of identifying which modems are seeking voice-QOS upstream links as a
reasonable means of assuring necessary performance, along with the inclusion of a
cell-based partitioning of packets in the upstream, known as "fragmentation,"
Cable operators are already experimenting with
"legacy" IP-voice systems that are on the market to get more experience with the
technology, Craddock noted. Moreover, some may move ahead with nonstandardized iterations
of IP-telephony services as the industry proceeds with testing and finalization of the
PacketCable standards, he said.
Indeed, noted Kent Elliott, president and CEO of Vienna
Systems Inc., a supplier of client devices and call-management systems that is working
with PacketCable, cable may be only four to six months away from being able to support a
very attractive second-line type of service.
"There's tremendous pent-up demand out there for
low-cost, highly featured second- and multiple-line services, which you'll see MSOs
pursuing," Elliott said.