A new generation of premises
devices pegged to recently completed advanced cable-modem
specifications will soon put the cable industry in position
to offer an unprecedented range of voice-enhanced data
services in the small-business sector.
To date, the industry's
pursuit of high-speed-data opportunities in the business
market has been spotty, at best. But operators will quickly
have an opportunity to take advantage of new voice-friendly
modems based on version 1.1 of the Data Over Cable Service
Interface Specification.
Those modems will deliver a
combination of data and multiple-line voice services at
extremely competitive prices, without the complications
surrounding voice-over-IP (Internet protocol) specifications
for first-line-type service.
"There's an absolutely
huge market opportunity for cable in the 'IP Centrex' market
space," noted Gord Boyce, general manager for the
Americas at Nokia's IP-telephony unit in Ontario.
"There are several trials in place where cable
operators are preparing to offer this type of service to the
business sector."
The IP Centrex concept is one
of several business-oriented applications where the
complexities of delivering 911 and other intelligent-network
features of the PSTN (public switched telephone network), as
well as lifeline power backup, are not issues.
Operators or Internet-service
providers using DSL (digital subscriber line) links can use
devices such as what Nokia is supplying to set up the remote
call-management functionalities of a traditional Centrex
service, which telcos offer as an alternative to
premises-based PBXs (private-branch exchanges).
So far, Boyce added, most of
the trials are under way in Europe, but the principles in
play there apply to U.S. opportunities, as well.
"Stateside MSOs see the same benefits, but they've been
waiting for the next generation of modems to become
available," he said.
With an IP-voice initiative
stemming from its recent acquisition of Vienna Systems
Corp., Nokia is one of several vendors offering products
that will allow cable operators to supply specialized voice
services in the near term as part of their high-speed-data
offerings.
"Carrier-class voice
services over IP are a ways off, but there's a lot you can
do with the technology at its present level of
maturity," Boyce noted.
These new applications also
include nonlifeline second or multiple-line services with
PSTN tie-ins through headend-based gateways, and
voice-over-VPNs (virtual private networks), where branch
offices or residential workers are connected to a large
corporate PBX system through a corporate IP-telephony
gateway, as well as to the corporate LAN (local-area
network).
Such connections provide
secured remote access to the full suite of corporate
headquarters-based functionalities in voice and data over a
single data link.
Santa Clara, Calif.-based 8x8
Inc., for example, is working with 3Com Corp. and Com 21
Inc. to develop combination cable-modem and IP-voice devices
for multiple phone connections in small businesses, said
Scott St. Clair, spokesman for the supplier of IP-voice and
videoconferencing components.
"Our four-port
'Symphony' [voice-over-IP] module currently costs $100 per
line, and it has the potential to go even lower as volume
increases," St. Clair added.
The Symphony module connects
the cable or DSL network to the twisted-pair wires that lead
to various telephone extensions at the customer premises,
serving to translate the signals between the legacy premises
equipment and the external IP system.
This allows up to four
separate calls to be conducted simultaneously at the
premises, with each user receiving standard dialtone and
dialing as if it were a standard PSTN connection.
"The module works with a
variety of call-agent protocols, including H.323, SGCP
[Single Gateway Control Protocol] and MGCP [Multimedia
Gateway Control Protocol]," St. Clair noted. "And
it comes with multiple codecs [coder/decoders for
translating and compressing signals] that allow you to use
fax [machines], PCs [personal computers] and other
appliances, as well as standard telephones."
This means if an operator
uses a call-agent controller based on the new PacketCable
Network Client Specification, for example, end-users will be
able to receive such features as call waiting, call
forwarding, hold and transfer, three-way calling and other
common capabilities, maintaining control over the features
through touch-tone phone keypads and voice menus in the
traditional manner.
The triggering mechanism to
activating such services will be the delivery of DOCSIS 1.1
modems, specifications for which were recently issued by
Cable Television Laboratories Inc.
While CableLabs doesn't
expect to begin the certification process for 1.1 units
until the fourth quarter, operators will have an opportunity
to begin running service trials using pre-certified modems
within that time frame.
For example, General
Instrument Corp. has committed to supplying a number of
IP-voice field trials before the year is out in conjunction
with the implementation of 1.1 functionality in
premises-mounted BTIs (broadband telecommunications
interfaces) and the use of call-agent and other management
software from Telcordia Technologies Inc. (formerly Bell
Communications Research, or Bellcore).
And Canada's Le Groupe
Vidéotron Itée committed to getting commercial voice
services under way by year's end, well before any 1.1 modems
are likely to be certified.
"We expect to see some
[1.1] modems certified in the March-April time frame, but
that doesn't mean product won't be available before that
time," CableLabs executive consultant Rouzbeh Yassini
said.
In fact, Yassini added,
operators are already installing 1.1-ready headend CMTSs
(cable-modem-termination systems) based on Broadcom Corp.'s
"3300" chip, which means equipment can be made
fully compliant with the 1.1 specifications through
downloads of software. "We're in very good shape for
1.1 with the CMTSs," he said.
While most of the 1.1 specs
apply to software overlaid onto the hardware specifications
already implemented in DOCSIS 1.0 modems, there is a
hardware functionality component known as
"fragmentation" that will require new chips to be
installed in modem chassis.
This means that while 1.0
modems can easily operate in conjunction with 1.1 CMTSs, the
1.0 modems cannot be field-upgraded to 1.1 functionality via
software downloads.
Fragmentation -- which
segments packets into shorter pieces to fill all available
bandwidth openings as efficiently as possible -- is one of
several innovations meant to improve operators' ability to
use the upstream portion of the cable plant to support the
quality-of-service requirements of IP telephony.
Other software-based elements
include dynamic QOS, which supports a mixture of
traffic-flow categories through a single interface, and new
scheduling algorithms designed to reduce latency and jitter
and to make more efficient use of bandwidth.
Another element of 1.1, which
was added relatively late in the specification-setting
process, is known as "payload header suppression,"
and it may require hardware modifications, depending on the
types of chips used in the modems.
This technique saves
bandwidth in the downstream, as well as upstream, packet
flows by eliminating packet-header information between the
modem and CMTS that is not needed for that leg of the
IP-signal transport.
"The technique adds a
couple of bytes of information in the header to deliver
enough information so that whatever is needed [out of what
has been removed] can be restored at the end points,"
explained Mark Sumner, a consulting engineer with Motorola
Inc.'s Internet Networking Group. "You're taking away
34 bytes on average and adding two, for a net gain in
efficiency of 32."
The 1.1 specs also include a
new layer of security that uses digital certificates for
modem authentication, and they define the approach for
implementing IP multicast over cable networks.
Yassini cautioned that while
DOCSIS 1.0 certification -- which is now in progress, with
five vendors certified -- has simplified the hardware side
of getting the 1.1 modems certified, the complexities of the
software components are certain to make certification of 1.1
a difficult process. "The software testing is really
complex," he added.
Certification of 1.1 isn't
the only issue operators have to be concerned about in their
preparations for introducing first-line IP-voice services on
a wide scale.
As previously reported,
AT&T Corp. has initiated an architectural approach to
meeting its high performance standards that could take much
longer to bring to market than the MGCP-based IP-voice
architecture.
Moreover, even if operators
choose to base their architectures on MGCP or its precursor,
SGCP, as several are, they are faced with the issue of high
power-consumption levels associated with the current
generation of DOCSIS modems, including the initial
iterations of the 1.1 versions.
As Yassini noted, today's
modems consume up to 5 watts of power, making it difficult,
if not impossible, to back them up with alternative,
battery-generated power supplies, either from the network or
from premises-based power packs.
"It will take roughly
another 18 months before we see external modems that consume
only 1 or 2 watts of power, which is the power level you
need if you're going to be able to back up voice over IP in
providing a lifeline service," Yassini said.
Vendors like Motorola are
working on compromises that would toggle down the modem
functions to accommodate lower power consumption at
something less than first-class performance levels during
power outages, thereby allowing backup power from batteries
to keep the lifeline system operating.
But this type of
functionality will not be available anytime soon and, in any
event, it won't meet the requirements some MSOs are setting
for first-line service.
All of this leaves the
industry in the state of having at hand a voice-over-IP
capability that could prove to be a compelling revenue
opportunity in the small-business and home markets for
second-line or other specialized services, while operators
wait for the "five-nines" (99.999 percent
reliability) version of IP telephony to materialize.
"People who are
currently spending $120 to $200 per month for phone service
might well be interested in a much cheaper service, as long
as they're getting what they want from the service,"
Yassini noted.
With the newly released
specifications for version 1.1 of the standardized cable
modems, he added, operators will be able to deliver QOS,
multiple lines and enhanced features in the IP domain that
are well suited to meeting surging market demand in the
small-business and SoHo (small-office/home-office) markets.
