Calling Over Cable: Will IP Catch On?
BY EVAN KOBLENTZ
Carla picks up her home telephone and makes a long-distance call to her
friend Marty. Nothing seems odd to them about having a long-distance
conversation, which happens about 280 million times every day in this
country, by the FCC's 1999 figures. But behind the scenes, there's a new
story to tell: Our heroine's standard Trimline is plugged into a cable
modem. Her voice is digitized and sent over the cable TV provider's IP
network to Marty's location, where a gateway rebuilds the call and routes it
over the PSTN through Marty's local loop.
The idea is not as far-off as it sounds. Working with equipment vendors
like Lucent, Nortel, Samsung, Tollbridge, and Motorola, cable television
providers in the U.S. and Canada are aggressively trying to make 2001 the
year they become reborn as next-gen telcos.
Thanks to deregulation and advancements in class 5 replacement switches
and IP telephony, the environment is ripe for providers with a fast enough
Internet connection and the proper development sense to become CLECs or
long-distance carriers, according to recent reports from the Cahners In-Stat
and Strategis Group research firms.
Through this summer, the cable-meets-VoIP movement may not seem so
obvious. All of the currently available cable telephony offerings use
circuit-switched technology. These services come from providers like Cox
Communications, AT&T, Cablevision, and Comcast. They've been successful,
too: AT&T Broadband, for example, announced signing up more than 75,000
users as of last month. And Mike Paxton, a senior analyst for the Cahners
In-Stat research firm, says that circuit-switched "is currently 90
percent of the cable telephony story, and will continue to be for the next
However, Paxton and experts from equipment vendors, cable carriers, and
other research firms agree that while circuit-switched is a unique interim
revenue stream, IP telephony over cable -- specifically, over managed hybrid
fiber/coaxial, or HFC networks -- is where the future of long-distance is
at, until the day when native fiber-optic lines are common.
Longer-term forecasts are equally optimistic. According to the Strategis
report, "Cable Telephony Forecasts," almost 12 percent of U.S.
households will have cable-based IP telephony by the end of 2005. The report
outlines how cable telephony subscriptions will transition from
circuit-switched to non-lifeline IP to lifeline IP. Lifeline services will
account for a quarter of that 12 percent, the report says.
"I don't think there's a company out there that doesn't think
they're going to see IP telephony," said Lucent Technologies' John
Slevin, director of strategy and business development for cable solutions.
Regarding the timing of such rollouts, he said, "the question is their
priorities. Some are more entrepreneurial than others."
BEHIND THE SCENES
Leading the research into IP cable telephony is the PacketCable working
group, a part of the CableLabs organization. This is the same group who made
DOCSIS 1.0 the cable modem standard. To address real-time applications like
telephony, they're developing DOCSIS 1.1, which adds measures like dynamic
quality of service (QoS). Because cable users share their pipes with
neighboring households, the dynamic QoS switches itself on or off as needed,
thus saving bandwidth for other callers.
Many other issues also face operators who want to become telephone
companies. PacketCable director Ed Miller said that the new standards
address many of these issues, such as voice quality in terms of latency,
fidelity, jitter, and packet loss at the customer end, and legacy signaling
support, data security and theft of service security, scale, and feature
deployment at the provider end. Other issues are provider-specific, like
implementing systems for PSTN gateways and gatekeepers, provisioning,
billing, and network maintenance.
The current trials are small in scale, but important players are
administering them. A trial began in Georgia late last year between Lucent
and High Speed Access Corp., and trials throughout the northeastern U.S. are
being conducted between Nortel Networks and Adelphia Communications.
AT&T, which owns TCI and MediaOne, is working with both Lucent and
Motorola. Set-top box maker Scientific-Atlanta partners with both Net2Phone
and Cox Communications, a test that also includes a video-on-demand service.
Time-Warner has trials underway in Portland, ME, as a value-added feature to
their Road Runner cable modem service. In Canada, Samsung and Vid�otron are
conducting one of the largest trials, reaching more than 2,200 users in
If the trials seem slow to deploy, notes a Nortel white paper called
"The Cable Telephony Opportunity," it's because developing IP
telephony that's easy enough for consumers to use is much more involved than
becoming a traditional CLEC or a cable modem service. The white paper makes
noteworthy points: Some of the IP telephony considerations are technical
architecture, PSTN-level reliability, PSTN-level feature set, and regulatory
"Technical architecture" refers to the actual network
infrastructure. Cable TV networks pass about two-thirds of the roughly 100
million U.S. households. About half of that network is currently equipped to
handle two-way data; Paxton expects the majority of the transition to be
complete in three years, since most rural households involve the most per
capita expense to reach.
What's unique about implementing this technology in residences compared
to an enterprise VoIP project, he said, is the distributed characteristic.
"You're spreading it out to millions of nodes. You have one switch for
each home instead of one switch for each office," he explained. For
operators, this means laying underground cable or leasing someone else's,
and dealing with federal environmental and labor issues.
By PSTN-level reliability, the issue referred to is
"five-nines" of uptime, with levels of latency and jitter low
enough to be imperceptible to the average human ear, and levels of fidelity
clear enough to match the famous Sprint "pin drop" claim. Most
voice-over-data networks use aggressive compression algorithms, reducing the
standard of 64 KB per call down to 16, 12, or even eight KB. Add to that
equation the issue of normal Internet traffic, and suddenly the
time-sensitive voice packets are stuck in rush-hour gridlock on the
information superhighway. The message to operators is clear: Only a
well-managed semiprivate network is acceptable if you want users to get the
The feature set issue is equally tough for operators to solve. Sending
voice packets is one thing, but what about conference calls, caller ID, call
waiting, and on-hold lamps? What of DTMF tones, fax signaling, stutter
tones, and flash-hooks? These and other features need to be addressed before
IP telephony over cable will be accepted into the mainstream. More vital
features like government-regulated wiretapping and number portability are
being dealt with in the DOCSIS 1.1 specification and various CableLabs/PacketCable
projects, but end-user features will largely be proprietary solutions.
FCC regulation is another challenging issue facing IP telephony in
general. This summer saw much fuss made over H.R. 1291, whereby the House of
Representatives voted to exempt ISPs "or any provider of Internet
access service" from Universal Service contributions. The controversy
stemmed from a last-minute addition to the bill, which states, "Nothing
in this subsection shall preclude the Commission from imposing access
charges on the providers of Internet telephone services, irrespective of the
type of customer premises equipment used in connection with such
This leaves the door ajar for Congress to treat any IP telephony provider
as a standard competitive carrier. Some of the biggest vendors in this space
-- including Net2Phone, ITXC, Dialpad.com, deltathree.com, and Phonefree.com
-- even staged a Washington, D.C. rock-and-roll rally. They argue that being
forced to pay into the Universal Service Fund at such a young and vulnerable
stage in the IP telephony industry's growth will surely suffocate it, maybe
even to the point of extinction. Some analysts went even further, arguing
that the bill amendment was the work of lobbyists for the big-ticket telcos,
who they say fear VoIP technology because it will undercut their price
models and offer better enhanced services.
Regardless of your opinion on the roots of H.R. 1291 or what it may mean,
one thing is certain: For new operators or for traditional cable TV
operators entering the IP telephony space, FCC regulation will be an
important issue to deal with in coming years.
COMPLICATIONS IN THE CABLE INFRASTRUCTURE
Dan Middleton, vice president for cable media solutions at Nortel, cites
other items for potential IP cable telephony operators to deal with. Among
them are the ability to see, understand, and avoid RF interference in the
HFC infrastructure, modulation techniques, and redundant network maintenance
using SNMP methods. He also cited the possible capacity limits of DOCSIS
1.1, although he and other experts agree that DOCSIS 1.1 is a vast
improvement over DOCSIS 1.0. For now, he said, "Getting footprint is
more important than the technology you're using."
The trick to meeting that challenge, says analyst Bruce Rapport, is to
roll out IP cable telephony systems with a better feature set and lower
costs than normal competitive carriers. Rapport's company, DST Innovis,
makes billing and other record-keeping software for cable telephony
The expanded feature set must include a powered line or some other method
of accomplishing primary line reliability levels, he said. Ensuring that
reliability is not easy, wrote NetSpeak
Corp. engineer Linden deCarmo in an article for TMCnet.com, but it can
be done with prudent CMTS testing of bandwidth and packet collision
Other experts note that enhanced features can also include unified
messaging, video-on-demand, and other real-time, multimedia applications,
any of which could make IP cable telephony lines distinct from their
While many people still see Internet telephony as being a niche or
hobbyists' technology outside of the enterprise, the promise of PSTN
quality, phone-to-phone connections, converged voice, data, and video, no
special dialing codes, and no special customer premise equipment other than
a cable modem is an attractive package that can offer a new revenue stream
for cable providers.
"This is a step closer to being a replacement for your traditional
telephone," Lucent's Slevin said.
Evan Koblentz is a technology editor for TMC Labs. TMC Labs is made up
of an experienced staff of engineers who acquire, install, evaluate, and
relay to readers the advantages and pitfalls of the latest hardware and
software for the CTI, Internet telephony, and call center/telemarketing
markets. They review products and services for Internet Telephony,
Communications Solutions, and C@ll Center CRM Solutions magazines.
to the August 2000 table of contents ]