VoIP unwired

Voice and wireless Ethernet might seem an odd mix, but for mobile workers or hard-to-wire areas, it can be the perfect combo.

Converged voice/data network projects can be tough, especially if you can't use any wires. That's what Mike Burns, a systems integrator, discovered when a client asked him to provide voice and data services to a gold-mining operation in the middle of a Laotian jungle. Burns faced a sticky situation - literally.

"The ground was mostly mud, so we couldn't bury any cables, and there were no poles where we could hang wire," says Burns, who is president of Nationwide Computer Systems, an ISP and integration firm in Fort Lauderdale, Fla. The solution would obviously be a wireless one: Burns used 802.11b gear to connect 50 IP phones, PCs, a router and satellite dish for the mining camp. The camp, which stretches over a two-mile area, consists of 20 structures for operations, living quarters and offices.

Wireless Ethernet certainly isn't the first infrastructure that experts recommend for carrying voice over IP (VoIP), but Burns and other users are finding 802.11 works fine for their IP telephony requirements. The combination of the technologies is proving useful for keeping mobile employees, such as hospital workers, in touch or for linking IP phones in areas where Category 5 cabling is hard to run.

Voice quality can be a major issue because Wi-Fi LANs are slow at 11M bit/sec, and in most cases, a shared medium, likened to 10Base-T hubs. The IEEE is creating standards to increase security and quality of service (QoS) on Wi-Fi - such as 802.11i and 802.11e - but widespread adoption of those technologies is still at least a year away.

While some users say IP voice quality is fine over Wi-Fi, others have adopted proprietary QoS features supplied by Wi-Fi and wireless IP phone makers to make sure of that. At the mining camp, where voice and data contend for Wi-Fi connections, Burns relies on router-based QoS.

Burns built a wireless VoIP network using an AltiGen Communications AltiServ IP PBX, Polycom IP phones, Lucent Wi-Fi access points - lashed to trees, Cisco hubs and a router, which connects to satellite equipment for outside communications. Hubs and Wi-Fi routers in the camp buildings connect the IP phones and connect to PCs for e-mail and mining data analysis. (More than a dozen gas generators power the network gear.)

Connecting the mining camp to the outside world was easy, Burns says. A satellite dish syncs up to a fiber connection in Germany, which ultimately runs to Nationwide's ISP point of presence in Florida. The hard part, he says, was connecting telephones down on the jungle floor for calls between buildings - or huts, as Burns calls them.

"There was no way we could have deployed a traditional PBX in this environment," he says.

"It was pretty out there," Burns says of the network, which is still operating. "I've thought about that project a lot, and there was no other way we could have done it."

Wi-Fi and VoIP, stat

At Mercy Medical Center in Roseburg, Ore., IT Director Nancy Laney could have given nurses regular phones or new pagers, but opted for wireless VoIP devices instead. The hospital uses wireless VoIP communications badge appliances from Vocera Communications.

Nurses wear the gadgets, about the size of TV remotes, around their necks with lanyards or pinned to their shirts. To reach someone, a nurse presses a button on the badge and scrolls through names in the system, then presses another button to talk. The voice signal travels to the recipient over the hospital's Wi-Fi infrastructure.

Mercy Medical installed 10 Cisco Wi-Fi endpoints throughout the facility to support the Vocera infrastructure, which replaces an outdated pager system, Laney says. Wireless VoIP lets nurses contact each other faster and more efficiently than previous pager systems or with telephones, she adds.

"We were going to install a wireless infrastructure anyway, so we just accelerated that project" when deciding to use the Vocera devices, Laney says. "After a 30-day trial, our nursing staff was hooked. We've had technology rollouts that met some resistance, but this is not one of them."

A Windows server running Vocera's management software and user database controls the Wi-Fi VoIP network on the back end. The software lets administrators add and remove users from the system and customize individual calling features. They can track users on the system using an open source MySQL database. The hospital uses interactive voice response (IVR) software from Nuance, processing voice-activated commands.

During emergency situations when nurses don't have time to scroll through names, they can use the IVR feature by voice prompt. Speaking a person's name, the name of a group or for all nurses on a certain team will initiate the call.

Users also can find where someone is through the Vocera system. They say "find" and the name of the person, and the IVR software responds with the location of the requested user. To make this possible, Laney has assigned all the Wi-Fi access points in the hospital a name based on their location, such as "Emergency," "OR" or "Cafeteria" and entered them into the Vocera database. The hospital even is attaching Vocera badges to frequently used pieces of equipment, such as EKG machines or defibrillators so nurses can find these devices quickly, Laney says.

Mercy Medical has plans to give nurses wireless tablet PCs, so the Wi-Fi infrastructure will soon be carrying data, too, Laney says. Because the Cisco access points can support the prioritization of voice traffic, Laney says she does not anticipate bandwidth-contention issues.

The Vocera system is slightly more expensive than the pager system it replaced, but Laney says she expects the hospital to save money ultimately because it is giving wireless VoIP access to other groups, such as doctors, maintenance workers and cleaning staff. These employees had used pager systems or walkie-talkies.

Similarly, at University of Southern California University Hospital (USCUH) in Los Angeles, nurses and doctors now stay in touch via 802.11b-based NetLink IP phones from SpectraLink. A total of 273 wireless IP handsets are in use at the hospital. Wireless IP phones are now a single source of communication for all staff, and replace a mix of communication methods used in the past such as nurse call buttons, a public address paging system and cordless telephones - which were inefficient, says Anthony Kellogg, project manager for USCUH.

Anticipating Wi-Fi VoIPThe wireless VoIP decision came after two separate infrastructure projects USCUH undertook last year. In the first, the hospital built a Wi-Fi network using Enterasys Networks gear to support mobile devices, such as laptops.

Calling CallManager

In the second project, the hospital installed a Cisco CallManager IP PBX to connect some remote facilities to a Nortel Meridian PBX over IP. USCUH brought those projects together when it chose to give the medical staff Wi-Fi phones. To ensure voice quality, the hospital relies on SpectraLink's NetLink SVP Server, which provides a proprietary QoS feature for giving voice calls priority over data. When the voice packets hit the wired network, they are placed into the first of eight priority queues on the Enterasys LAN switches.

CallManager - a redundant Windows server running Cisco's IP PBX software - routes all calls inside the USCUH. (The majority of the SpectraLink traffic is internal.) CallManager also provides call-control features, such as call forwarding, hold and dual-line support. While most VoIP calls are internal, SpectraLink phone users can place external calls, too. The VoIP traffic converts to regular voice as it moves from the CallManager to an ISDN line, connecting that IP PBX to the Nortel Meridian PBX.

While adoption of wireless LANs isn't expected to outpace wired networks anytime soon, and land lines for voice are still king in most organizations, users willing to push the IT envelope are finding that Wi-Fi VoIP is more than just the combination of two industry-chic acronyms.

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