Managed and Centrex and hosted, oh my! For companies looking for an
alternative to a premise-based phone system, there are plenty
available, and they come in all shapes and sizes. Hosted voice, IP
Centrex, managed IP PBXs and network-based voice service are all
viable alternatives to the do-it-yourself model. But these terms
are often used interchangeably -- incorrectly in most cases --
causing confusion among the buying community as to which product to
use in what situation.
For many organizations, the complexity of running VoIP is more
than the IT department wants to deal with, so an outsourced
solution seems appealing. Sifting through the various offerings can
be quite confusing, however, and leaves potential buyers scratching
their heads as to exactly what the service is and how it works. A
clearer understanding of exactly what's available will help you at
least ask the proper questions to distinguish between the services.
Of course, this assumes that the people selling the product also
fully understand the differences between their offerings, which
isn't always the case!
The products
When considering an outsourced service, there are four basic
product categories. Hosted IP PBX, managed IP PBXs, network-based
services and IP Centrex. The basic premise of all of these services
is that a third party manages everything and provides a "service"
to the organization -- but they do differ. The main benefit of an
outsourced service is that much of the risk is transferred to the
service provider, but the customer does lose direct control of the
solution.
Managed IP PBX
This is where the traditional IP PBX is on premise. The enterprise
could choose to manage the products itself but chooses to outsource
the management to a third party. It's important to note that not
all managed services are created equal. They range from simple
moves, adds and changes up to fully outsourced management of the
entire lifecycle of VoIP. Most VoIP services today are managed
services and are offered by most telcos and systems integrators,
and even by many vendors such as Avaya and NEC Unified
Solutions.
 | | | | | The main theme behind a hosted,
IP Centrex, and network-based voice service is that the call
control is somewhere "in the cloud." All that's needed on the
customer premise are IP phones and a router.
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Hosted IP PBX
A hosted IP PBX is no different from any other hosted application,
such as email. Instead of the IP PBX being located on the customer
premise, it is located in the vendor's hosting center. The IP PBX
is exactly the same one that would be purchased and placed on
premise, meaning that the company is buying "hosted Cisco" or
"hosted Avaya," so it interoperates with the premise-based
equipment. Some companies "host" the IP PBX themselves by placing
the IP PBX in their own data center, and then every branch office
picks up the call control from there. A few companies I've talked
to have put the primary IP PBX in their own data center and the
backup in a third-party hosting center. The systems integrators and
VARs are the primary deliverers of hosted IP PBXs. An interesting
option for Avaya customers is Avaya's On-Demand voice service,
delivered in partnership with Savvis.
IP Centrex
The term "IP Centrex" is an overused tag used to describe anything
where the call control is located in the network instead of the
branch. There are many carrier services that carry the Centrex
name, but most of them are actually much more than an IP version of
a traditional Centrex service. A true IP Centrex service has an IP
gateway placed in front of a traditional Class 5 switch, with the
service delivered over IP, but the basic service is still a
traditional Centrex service. The growth potential of this type of
service is limited because many of the advanced unified
communications features cannot be delivered this way. Also, in the
U.S., Centrex services haven't been overly popular; IP enabling it
makes it a little easier to deliver, but the stigma of Centrex
still applies to it. As far as I know, there are no major carriers
that offer an IP-enabled Centrex service. A few rural ILECs do, but
the growth in cloud-based voice services is in a true network-based
service, highlighted below.
Network-based voice
A network-based service is similar to a hosted IP PBX but with a
couple of differences. First, the infrastructure -- known as a
softswitch -- which provides the call control, is located in the
telco network, not a hosting center. The softswitch is designed to
be a multi-tenant product, meaning that it can house the calling
capabilities of multiple customers, whereas a hosted IP PBX is
deployed on a per-customer basis. The softswitch has been
positioned as the IP equivalent of an old Class 5 switch, but a
softswitch is more of an application server that's capable of
serving up applications other than just voice. Any service built
from a softswitch is capable of delivering many of the unified
communications applications as well. One mistake many carriers have
made is branding their softswitch-based services as "IP Centrex"
services. For example, Verizon's Hosted IP Centrex service is
actually a network-based service built on Broadsoft infrastructure
and is much more than just a basic Centrex service. AT&T's
Voice DNA and Vonage's phone service (consumer) are also examples
of this. Organizations considering a cloud-based service should do
the due diligence to understand exactly how the service is
delivered and the long-term roadmap of the service. The downside to
these services is that the infrastructure that provides the service
needs to adhere to industry standards, meaning that the features
are limited to ones that have made their way through the standards
bodies. Most premise-based IP PBXs from vendors such as Cisco and
Avaya also adhere to standards, but they add on extra features
through proprietary extensions to the standard. In many cases, the
standards-based features available should be sufficient for many
organizations, but companies considering this type of service
should keep this in mind. As time marches on and the standards
mature, the gap between proprietary features and standards-based
features will close.
| | | | | Even if you're a predominantly
do-it-yourself IT organization,consider a hybrid environment where
the hosted services are used for some of the smaller branches and
telecommuters.
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The main theme behind a hosted, IP Centrex, and network-based voice
service is that the call control is somewhere "in the cloud," and
all that's needed on the customer premise are IP phones and a
router for the data services. Telecommuter phones and PC-based
softphones can also interoperate with these services.
Even though the industry has done a great job creating confusion
among all the available VoIP services, I do think they're a good
alternative to organizations that want to offload much of the
up-front expense of buying the equipment and the ongoing
operational costs associated with managing the equipment. If you're
considering a service, though, keep a few things in mind.
Understand the architecture behind the service
Many of the services have been branded with names that don't
accurately describe them. For example, a name like "Hosted IP
Centrex" service doesn't really describe whether it's a true hosted
service, Centrex service or network-based service.
Do the due diligence and understand what features are
available today and what's on the roadmap
Most of the softswitch-based services are relatively new, so the
majority of features are yet to come.
Even if you're a predominantly do-it-yourself IT organization,
consider a hybrid environment where the hosted services are
used for some of the smaller branches and telecommuters. This will
probably scale much more easily for you as you move more locations
over to VoIP.
Zeus Kerravala manages Yankee Group's infrastructure research
and consulting. His areas of expertise involve working with
customers to solve their business issues through the deployment of
infrastructure technology solutions, including switching, routing,
network management, voice solutions and VPNs.
Before joining Yankee Group, Kerravala was a senior engineer
and technical project manager for Greenwich Technology Partners, a
leading network infrastructure and engineering consulting firm.
Prior to that, he was a vice president of IT for Ferris, Baker
Watts, a mid-Atlantic based brokerage firm, acting as both a lead
engineer and project manager deploying corporate-wide technical
solutions to support the firm's business units. Kerravala's first
task at FBW was to roll out a new frame relay infrastructure with
connections to branch offices, service providers, vendors and the
stock exchange. Kerravala was also an engineer and technical
project manager for Alex. Brown & Sons, responsible for the
technology related to the equity trading desks.
Kerravala obtained a B.S. degree in physics and mathematics
from the University of Victoria (Canada). He is also certified by
Citrix and NetScout.