Hospitals are finding voice over wireless LANs to be just what the doctor - and more to the point, the nurses - ordered. While VoWi-Fi technology is hardly commonplace yet, its growing acceptance in life-or-death situations is a testament to the value of convergence  and mobility.

"Healthcare has high-value people in information-intensive jobs who move around constantly and play different roles at different times," says Eric Brown, a vice president at Forrester Research. "It's the perfect combination for VoWi-Fi."

VoWi-Fi also helps boost productivity amid an acute nursing shortage by eliminating the need for nurses to waste time searching for phones to use. "Hospitals need VoWi-Fi because nurses don't sit behind desks," says Craig Mathias, principal analyst at Farpoint Group.

The need to improve communications and provide better access to resources drove Overlake Hospital Medical Center onto VoWi-Fi's bleeding edge three years ago.

"Our two biggest issues were roaming and security," says Kent Hargrave, CIO of the 337-bed facility in Bellevue, Wash. Overlake settled on Airespace for its 802.11b/g WLAN infrastructure, citing superior roaming capabilities, ease of implementation and management , and scalability. "It also cost about 50% of the other solutions," Hargrave says.

The client devices and voice switches at Overlake are mixed. Clinicians needing hands-free communication are equipped with Vocera badges, while handsets include Cisco 7290s and the Avaya /SpectraLink 3626.

Cisco's Call Manager is deployed in one department while an Avaya Media Server serves the rest of the hospital. The Avaya product is the current favorite, integrating with Overlake's Avaya PBX and extending voice mail and call forwarding to the wireless network. But increasing wireless handset use to enter medical data via XML eventually could tip the scales in Cisco's favor, Hargrave adds.

Because Overlake deployed its WLAN before the 802.11i standard was finalized, the hospital shored up security by implementing Wi-Fi Protected Access  and configuring the access points so they don't broadcast Server Set Identifiers. Products based on 802.11i will be evaluated as they become commercially available.

Children's Hospital Central California in Madera let VoWi-Fi mature a bit before jumping on board. The 255-bed pediatric hospital started putting voice on its 802.11b WLAN in mid-2003.

The network includes an Avaya PBX, SpectraLink-manufactured Avaya 3606 and 3626 handsets and Cisco 1200 access points. Wired Equivalent Privacy security is enhanced by segregating the phones on a separate virtual LAN .

A pilot project revealed bugs requiring firmware upgrades. The centralized Dynamic Host Configuration Protocol  servers weren't on the same subnet with the phones, and requests had to go across routers in packets of at least 300 bytes. The phones wouldn't allow packets that large until SpectraLink developed a fix.

Similarly, Cisco had to tweak its access points to reduce an SNMP polling latency that went unnoticed when the WLAN was data-only. The access points were pausing the radio signal for about a second whenever they received a request from the WaveLink Mobile Manager management application.

"Still, it only took a one-month pilot to get these bugs worked out," reports Joseph Egan, Children's network engineer. Children's is now testing a push-to-talk feature on the 3626 phones to broadcast Code Blue alerts that summon emergency teams.