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Evolution or revolution? That's the big decision to make as you move down the convergence path toward voice over IP to the desktop. Established PBX vendors such as Nortel Networks are marshalling a gateway-based coalition between the old and new, while Cisco and its IP forces are trying to stage a complete overthrow.
The debate has gone on for years in slide-show sparring duels, but it escalated into a real-world street fight when IP PBX sales started to increase this year. LAN telephony sales increased from $2.9 million to $40.7 million between the second quarters of 1999 and 2000, according to market research firm Synergy Research Group.
Cisco shipped its Architecture for Voice and Integrated Data (AVVID) platform the first enterprise class IP PBX in mid 1999, and 3Com has seen continued success selling its NBX line into small and midsize business sites.
"We started hearing more from the established PBX vendors in the third quarter of 2000, when the threats from these nontraditional players began to get real," says Jeremy Duke, Synergy's president. "This is a disruptive technology, and a big part of the PBX business has been flat or even declining."
The gateway approach to LAN-side voice over IP is more cautious and incremental, preserving investments in traditional PBX platforms and leveraging their vaunted stability and "five nines" reliability. The PBX continues to handle call processing, while the line-provisioning functionality is off-loaded to the IP network
A gateway board in your PBX packetizes and compresses voice for transmission over IP and functions as a proxy server and virtual line card for IP phones that are plugged into Ethernet jacks. A gateway card with 24 ports can support up to 96 of these phones, so you can squeeze more capacity out of a PBX by supporting new users through voice over IP.
In contrast, IP PBX systems replace the center stage switch fabric in the traditional PBX hardware with the IP network and move the call processing to an open server typically Windows NT. The call processing and PBX functions such as call switching, trunking and station access can be distributed across different platforms or even outsourced. Of course, this flexibility means increased complexity and integration overhead.
The PBX faction questions the reliability of the data infrastructure but acknowledges that properly configured Ethernet networks with state-of-the-art switches are approaching the same 99.999% uptime that voice networks have achieved. The weakness is the NT server, which tends to destabilize and requires regular rebooting. Traditional PBXs are comparatively closed, but will run indefinitely without rebooting and can be patched without disrupting operations.
Gateways enable telecommuters
Symantec is an evolutionist that has embraced the gateway approach to convergence, although the initial focus is on remote desktops. Located in the middle of Silicon Valley, where rush-hour traffic congestion is rising almost as fast as housing prices, the software developer needed a way to provide full PBX features over DSL lines to its growing population of home workers.
Because it had a fairly homogeneous voice network with more than 40 Nortel PBXs worldwide, Symantec decided to alpha-test a Nortel line-side gateway card to deliver voice over IP to telecommuters. A small hub is placed in each home, and users plug their computers and phones into it. Voice and data can be delivered simultaneously over the same DSL connection, so no second line has to be installed for data.
The employee has the same phone number at the office and at home, and the phones ring in both places when calls come into the enterprise PBX. The local and remote IP phones support the same functions, including call transferring, conference calling and message-waiting lights. The gateways provide four times the port density of a traditional PBX line card, so Symantec is using them for expansion on campus.
"There is a big cost savings when you don't have to buy another shelf in the PBX," says Neil Kole, director of communications and engineering at Symantec. There are also administrative savings because it's easy to install and move phones.
"You just plug them in the jack," he says. "With traditional phones, someone with the proper skills has to move a cable pair or do some programming on the PBX."
Kole says the latest upgrade removed the last perceptible imperfections in the voice quality of the IP phones, and he now has no reservations about rolling them out anywhere.
IP PBXs are another story, however.
"We played with an IP PBX, but we were concerned about the reliability issues. Even if I had a green-field opportunity in a new branch office, I would put in a PBX with a gateway card to deliver [voice over IP] to the desktop," he says.
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