August 2, 2004

Open source helps power SIP phone popularity

Author: Mary E. Tyler

VoIP (voice over Internet Protocol) is being heavily hyped these
days.  Systems come in various sizes, supporting anywhere from 25 to
1,200 users across multiple locations, time zones, and continents,
and open source products are available across the spectrum. The
reason for adopting VoIP is simple: the cost savings involved with
putting voice and data on the same network. The argument for open
source in VoIP is similarly simple: solutions that make use of open
source software are less expensive than traditional PBX or Centrex
systems and proprietary VoIP solutions.

Until recently, open source VoIP was seen as a low-end (less than
25 extensions) solution. For high-end uses, there were only
proprietary products. But according to Rick
Segrist, spokesperson for Digium,
a VoIP hardware manufacturer, interest is increasing in open source
solutions, mainly from call centers looking to save money. "I can think of
three or four big ones -- thousands of people people each," says Segrist, regarding call centers
that have installed open source-based VoIP systems in the last year.  

There are three components to any VoIP solution: hardware,
software, and protocols. Most solutions, whether proprietary or open
source, use the same set of open protocols. Session Initiation
Protocol or SIP drives most of the industry and is used by industry
players from Skype and PhoneGAIM to Apple Computer's iChat AV. According to Jon
Arnold, VoIP program leader for Frost & Sullivan, proprietary
products from Cisco, Siemens, Lucent, and 3Com support SIP somewhat,
often using variants which do not intercommunicate as well as those
that stick to the standard. "The proprietary protocols are their competitive
advantage, but they all know it is going to be a SIP world," says
Arnold. "They don't want to support SIP, but they know they can't
avoid it down the road, so they do."

Enterprise SIP systems have a server component and a client
component. The servers can be self-contained, or can be a generic
computers, often running Linux, with a special telephony board. The
software, usually providing PBX functions, can be proprietary or open
source. The clients can be hardware (a physical phone) or software
that functions like a phone and uses a computer's microphone and
speakers for I/O.

A good example of a self-contained solution is  the MX line of products
from Zultys, which run embedded
Linux."We chose Linux years ago, when it wasn't clear [that Linux
would be a winner in VoIP]," says Patrick Ferriter, vice president of
product marketing for Zultys. "We interviewed quite a few other
solutions. The other guys weren't willing to work with us. They were
arrogant, sure they dominated the market." So Zultys worked with Montavista to port embedded Linux
to the IBM 440 GP processor. By working with Montavista, Zultys got
access to the operating system about six months before it was
released to competitors. According to Ferriter, this was
crucial in getting the company's products to market sooner.

Zultys, like most VoIP server vendors, uses an open standards
approach to providing VoIP on a Linux base. It uses SIP to establish calls and fax connections. It uses Voice XML for automatic attendants ("If
you hate automated phone systems, please press 1") and voice mail. It
also uses MXIE (Media
Exchange Interface for End Users) and TAPI (Telephony API) from Microsoft to enable the phone system to pipe
data to Windows-based databases and be administered from Windows.
That's just the nature of the beast, according to Zultys. Its hardware runs
Linux, but the company's clients generally run Windows and want to be able to
access the system from Windows.

In the second server approach, open source software, like Digium's Asterisk, runs on generic Linux boxes outfitted with compatible telephony boards to provide full-featured
PBX functionality
. Digium spearheads the Asterisk development as
a loss leader, customizing its telephony boards to work
with Asterisk and making money by selling them for use in the Linux-based Asterisk servers.

Digium dual-licenses Asterisk (and a variety of other
) under a commercial license as well as the GPL, but the
installation and integration of large VoIP systems is usually done by
a reseller or integrator
such as Redfone Communications. Redfone itself had used Asterisk for two small businesses: a software
company and an engineering firm. "We installed it, used it, loved
it," says Steve Lynn, Redfone's president. "There was no real
commercial version, but we liked the product, so, well, we 'bought the
company,'" Lynn jokes. "That is, we created a company to
commercialize Asterisk."  

Redfone put together marketing materials, a
sales force, and a technical team to do installations. Asterisk didn't require
any software changes as such. According to Lynn, it was mainly
standardizing the configurations for various Linux distributions and
hardware choices, and changing how
hardware and software resources were used to make Asterisk more
"commercially robust." "We did create some of our own applications that run
with Asterisk," Lynn says. "For example, [we added] a recording
system [based on MySQL] that tracks calls for billing and lets
companies charge back among their own units."

With the software-based systems, an integrator normally prices
service based on the number of extensions multiplied by a rate determined by
a variety of factors, including the level of usage, whether the
station uses an Internet phone or a regular phone, and whether there is a call
center agent involved. The integrator provides the hardware, complete
with the telephony boards, including rack-mounted servers for large

In addition to servers, Redfone also offers complete packages:
support, maintenance, and administration; telephony
writing and physical phones. The telephones cost anywhere from about
$100 for a low-end generic model to $600 for a high-end Cisco phone.
But for Lynn, the best thing about open source VoIP isn't about
Redfone making money. "It's a
large-company solution that is affordable for small companies," says
Lynn. "It competes with anything on the marketplace. It's free, and if
you have the capability, you can implement it yourself."

Future looks bright

In the long term, IP telephony is going to begin to take over the
market, according to Frost & Sullivan's Arnold. However, except in the "green fields"
where there is no telephony currently, enterprise growth is driven by
the replacement cycle of traditional PBX hardware. Really large
enterprises with tens of thousands of users are not sure the IP
solutions will scale, though vendors insist they will. These
enterprises are dipping toes into VoIP, moving a few hundred to a few
thousand users at a time.

This is good news for open source VoIP
vendors, since their solutions top out at about 1,200 users and can be
provided at lower cost. This also puts open source vendors in a
strong position to overcome the most common argument against the
switch. "It's easy for companies to argue that the ROI isn't strong
enough," says Arnold, explaining why companies might hang back from
replacing traditional PBXes that "work just fine, thank you."
"They're not in a hurry. This is no killer app yet. It may never be
one. But everyone's in love with the technology and it does have its


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