The demise of many of the most aggressive broadband CLECs and the lack of
public announcements by large carriers have made many in the industry
question the progress of voice over DSL (VoDSL) this year. But it is
during the quiet following the storm of hype surrounding voice over DSL
that we are seeing the first real progress that will result in mass
deployment of this technology. The standards and interoperability progress
made to date have ensured that VoDSL did not sputter out before it got
Much of the progress made was done through a coalition of companies
called OpenVoB. OpenVoB was formed to
accelerate the adoption of voice over broadband. The group -- made up of
silicon, IAD, gateway, and softswitch vendors -- is dedicated to enabling
multi-vendor interoperability based on existing and emerging standards for
voice over broadband. Leveraging existing and emerging standards, OpenVoB
members were able to tackle some of the most challenging VoDSL technical
issues head on.
The Year In Review: VoDSL In 2001
This time last year, the majority of voice over DSL solutions available
were proprietary. These early solutions enabled several data CLECs to
begin testing voice over DSL, however the technology's adoption by larger
carriers was limited because they were unwilling to deploy another
proprietary solution in parallel to the proprietary telecom architecture
they already had in place. The ATM and DSL Forums standardized Class 5
derived voice over DSL in the form of the Loop Emulation Standard. The
availability of this standard, and the support of the large carriers, made
it possible for a host of vendors to begin implementing standards-based
solutions for voice over DSL.
End of story, right? So why didn't VoDSL take off like a rocket? The
problem begins with interpretation of the accepted standard. Each vendor's
unique interpretation of the standard often results in very limited
interoperability between vendors. In order to encourage service providers
to test and ultimately deploy voice over DSL technology, the vendor
community had to furnish service providers with evidence that any-to-any
interoperability based on standards was not only possible, but also
already tested and available.
The first step was to select a baseline set of implementation profiles
for the Loop Emulation Standard. Once selected, members of OpenVoB created
a test plan which it then executed at the University of New Hampshire in a
series of interoperability events. Silicon, IAD, and gateway vendors
worked together to establish a baseline of any-to-any interoperability.
The outcome was the first publicly available implementation guide for the
Loop Emulation Standard.
This document, which allows public access to the methodology of the
standard's implementation, significantly increases the probability of
multi-vendor interoperability, lowers the individual vendors' cost to test
interoperability, and offers service providers a guarantee that the
standards-based products, implemented to the test plan, will in fact work
together. (Visit www.openvob.org to
download the complete implementation guide).
The significant progress made culminated in a public multi-vendor
interoperability demonstration in April 2001. What took years for DSL
equipment manufacturers to accomplish from an interoperability perspective
was proven out in the VoDSL market in less than one year.
These efforts resulted in the acceleration of lab and field trials of
voice over DSL technology by large carriers, allowing them to move to the
final stage prior to mass deployment: operationalization. This
behind-the-scenes work, while not as visible as other stages in the
market's development, is a true indicator that voice over DSL is moving
beyond the hype.
Looking Ahead: VoDSL In 2002
Mass deployment in 2002 relies on several factors. First, a business case
has to be made for the technology. The cost structure of the equipment and
network architecture cannot exceed what exists today, and the technology
must deliver tangible benefits to the service providers' customers,
including lower costs, new services and increased flexibility.
Second, the regulatory environment has to encourage competition without
eliminating incentives for incumbent providers to deploy new services and
architectures. Voice services have always lived in the regulatory domain,
and incumbent carriers are very wary (from a regulatory perspective) of
mass deploying technology that marries the voice and data world without a
clearer understanding of what the impact will be on the bottom line.
Finally, there are still technical hurdles to overcome as service
providers begin the long and difficult process of operationalizing voice
over DSL into their network. Two of these hurdles include flow through
provisioning, and softswitch-based voice over broadband.
Flow Through Provisioning
Flow through provisioning enables service providers to automate the
provisioning of new services, eliminating costly, time-consuming, and
error-prone manual processes while enabling them to benefit from the
revenues generated by customer access to on-demand services. Voice over
DSL is a losing proposition if it relies strictly on manual processes --
the costs are prohibitive and the services can't scale.
The ATM Forum's Management Information Base (MIB) for CPE management
using the LES Embedded Operations Channel, which went to final ballot at
the ATM Forum meeting in July 2001, will enable service providers to
auto-provision customer premise equipment through the voice gateway EMS,
or Element Management System. This capability, once tested in a
multi-vendor environment, dramatically simplifies the provisioning
process, eliminating unnecessary complexity in the network, and lowering
the overall costs of deploying VoDSL service.
Softswitch-Based Voice Over Broadband
Service providers intend to not only deploy derived voice services from a
Class 5 network, but also from networks based on emerging IP and
As a result, the ability to deploy voice over broadband technology
using softswitch-compatible IP signaling and media protocols is critical
to its acceptance as a strategic platform for service providers' long-term
deployment plans. OpenVoB has created a test plan to begin the early
stages of interoperability testing for voice over DSL based on existing
and emerging Multiservice Broadband Network (MBN) standards for access
networks. The group's intention is to focus on the problem of toll-quality
VoIP over the "last mile."
Dead Or Alive?
Voice over DSL is alive and well. While the technology has not ramped up
as quickly as hoped, the inherent complexity associated with changing
decades of circuit-switched voice made it impossible for VoDSL to become
an overnight sensation. However, the migration from circuit to packet in
the service providers' networks is very real, and voice over DSL plays a
starring role in that transition.
2002 will be a very important year for vendors to provide service
providers with the mature, standards-based, proven technology required to
seamlessly integrate voice over DSL into existing networks for mass
Ken Cavanaugh is director of business development at General
Bandwidth and the chairman of OpenVoB.