• United States
by Paul Korzeniowski

VoIP and WLAN – a dreamy new combo

Aug 23, 20048 mins
Cisco SystemsNetworkingVoIP

Three early adopters tell how they’ve paired VoIP and WLANs as part of their new data center plans.

Wireless LANs and VoIP are two new data center hotties gaining admirers because of the productivity improvements they offer. No surprise, then, that a growing number of companies are pairing these stars – and so far, the union is proving much stronger than J.Lo’s and Ben’s had been.

“Now that VoIP has proven itself to be a viable, easy-to-use technology, enterprises are searching for ways to leverage its capabilities, and one way is to run it over their WLANs,” says Allen Nogee, a principal analyst with In-Stat/MDR. The research firm found only 60,000 VoIP handsets were deployed on WLANs in the U.S. in 2003, but that almost half the companies it surveyed are examining the technology for future deployment.

Pacific Sunwear of California, Condell Medical Center and the town of Ocean City, Md., are among early adopters of VoIP over WLANs. The attraction for VoIP over WLAN differs among them, but all have reaped benefits from their installations. Even call-quality issues haven’t dampened their enthusiasm for the technology.

A sunny forecast

For PacSun, an Anaheim, Calif., specialty retailer of teen apparel, accessories and shoes, WLAN technology came into play as it moved into new headquarters and distribution center buildings. “Because of our rapid expansion, we have been tripling in size and outgrowing our building requirements every four years,” says Ron Ehlers, vice president of IS at PacSun, which operates more than 900 stores in the U.S. “In 2002 for the first time, we had the opportunity to build the corporate offices, data center and distribution center the way we wanted. Previously, we had to fit our requirements into existing buildings.”

The company went with Cisco Aironet WLAN access points in its corporate office, which has 300 users, and Symbol Technologies handheld and truck-mounted systems for its warehouse, which has about 150 employees. Initially, the 11M bit/sec 802.11b links were used only for data applications. When traveling to department meetings, corporate employees used laptops to access and analyze information, such as individual-store sales data or product pricing. In the warehouse, employees used portable scanners to examine inventory data.

The network design paid big dividends, especially in the distribution center, Ehlers says.

“In our old facility, our warehouse management system was an antiquated manual system,” he says. “The new building has an automated, paperless system, and since we’ve been in it, we have grown by 160 stores, but our distribution center costs as a percent of sales have gone down.”

Yet this bright tale came with two dark sides. Employees, especially those in the distribution center and network service center, spent a lot of time away from their desks and missed important calls. PacSun looked at various options, including wireless radio systems, walkie-talkies and cellular services. All were expensive and would have required additional infrastructure investments. The retailer had an Avaya Definity PBX, but its 802.11b option was based on a proprietary design that would have required new access points.

In sifting through his e-mail, Ehlers saw a press release from Spectralink, a vendor about which he knew nothing. The company said its products worked with major PBXs and ran over 802.11b networks, so he called. “The company’s sales representatives brought the products into our conference room, unplugged a wired connection, made a few adjustments to the PBX and had a working WLAN phone in less than half an hour,” says Ehlers, who has outfitted about 30 employees with the new phones.

Call quality, while initially not an issue, became the second dark side as WLAN traffic increased. “We have areas in the data center, near the network services team, and in a few conference rooms where managers are constantly working with laptops,” Ehlers says. “As we placed more devices in those areas, users encountered garbled connections and dropped calls, especially when they moved from one access point to another.”

After conducting a site survey, Cisco recommended increasing the number of access points from 16 to about 25. PacSun was determining where to station more access points when Ehlers came across Meru Networks, whose access points rely on proprietary technology to squeeze out more (as many as five times more) connections over a typical 802.11b LAN. Swapping out the 16 Cisco access points for the Meru gear also let the retailer deploy a guest-access capability so clients or partners can access the Internet while at the retailers’ offices.

The right prescription

Product obsolescence led to a VoIP-over-WLAN deployment at Condell Medical Center, a community hospital in Libertyville, Ill., with about 200 beds and 2,700 employees. To improve patient care, the medical center provided nurses with laptop computers and wireless phones connected to an Avaya Definity PBX in 2001. Not only were the nurses able to enter patient data, such as temperatures and medication at the bedside, but doctors and nurses also could communicate more easily.

When the PBX vendor decided to drop its proprietary wireless phones for WLAN phones in 2003, the hospital decided to follow suit. However, cost was an issue: The VoIP phones cost about $700 each, and the hospital had to tack on another $200 to $300 per phone for batteries, chargers, cases and other accessories. “We decided to bundle our VoIP costs in as part of a $90 million expansion, for our emergency department, intensive care unit and a new women’s center and spa,” says Susan Mesmer, communications supervisor at the healthcare provider.

The hospital has about 325 nurses, technicians, transportation staff and managers working with mobile phones. When they started to work with the VoIP phones at the end of 2003, call quality became an issue.

“Nurses found intermittent jitter on lines in high traffic areas; the problems were quite clear whenever they moved from one access point to another,” Mesmer says.

This year, the hospital increased the number of access points from 25 to 45 and tweaked its network so VoIP calls receive the highest priority for network bandwidth. These steps assuaged all of the call-quality concerns.

Catching the wave

The town of Ocean City, which sits on a 4-mile-by-10-mile island, found an unusual application for VoIP over WLAN: its backbone network. The municipal agency supports about 400 users in 17 diverse locations ranging from a skateboard park to a police department. In the summer of 2002, it had two telecom challenges: It needed more bandwidth for new applications, such as a geographic information system that would send large graphic files from user to user, and its phone systems (each agency picked its own) were inefficient.

To solve the problems, the town totally revamped its telecom framework. For its voice needs, the town selected Avaya’s 8700 IP PBX and half a dozen distributed nodes that support 450 extensions, which are mainly IP phones but include a few fax modems. For the backbone network, the city put in Proxim dual-backbone 54M bit/sec WLAN radios, in a point-to-multipoint configuration with radio antennas placed on top of a series of water towers that line the island.

It selected Business Information Group, a York, Pa., reseller for the job, which was completed in April 2004. “During the evaluation process, it became clear that a few bidders planned to rely on subcontractors for the installation,” says Gail Weldin, Ocean City network manager. “Because our configuration was unique, we wanted the primary contractor to take care of any installation problems directly.”

VoIP-over-WLAN deployment tips
Find a vendor experienced in both WLANs and VoIP.

Conduct a site survey that identifies

probable WLAN voice and data users and their usage patterns.
Place access points to achieve sufficient overlap between locations.
Identify potentially congested areas and plan for additional access points there.
Be prepared for jitter and call dropping when the network is first installed.
Monitor network usage to identify bottlenecks.
Re-examine your network configuration every three months and expect to make changes once or twice per year.

Because the network supported vital voice and data transmissions, network management was important. The primary source needed to be able to supply 24-7 monitoring, but many had network operations centers that only operated from 8 a.m. to 5 p.m., Monday through Friday. And if a problem arose, the town needed technicians who could scale the water towers and tinker with the network equipment. In some cases, vendors would have made the city wait three or four days for a climber, an unacceptable timeframe.

The new system represents a $1.2 million investment, an expense the town expects to recoup in five years, Weldin says. By eliminating a few frame relay and T-1 lines, the municipal agency cut its annual telecom costs by $90,000. Employees now take care of any adds, moves and changes – tasks that Verizon previously did.

Initially, Ocean City employees encountered what Weldin termed “gobbledygook” on their connections. After some testing, the town discovered the interference problems stemmed from Verizon’s T-1 line. After that line was reconfigured, the problems disappeared.

Weldin points to a three-hour conference call among three groups of engineers, including one vendor’s team on the West Coast, as a measure of the network’s stability.

“We loaded up the network to test its throughput, and there was not a beep, an echo or a problem the entire time. For me, that verified that VoIP-over-WLAN technology is quite stable,” she says.

Korzeniowski is a freelance writer in Sudbury, Mass., specializing in technology issues. He can be reached at