Companies that worried about loading down their WLANs with the overhead of voice over Wi-Fi are seeing the equation change as 802.11n enters the mainstream. The attraction of Vo-Fi is clear: By integrating voice over IP, cellular telephony, and Wi-Fi, a new age of mobile voice and data services becomes reality. So what's the holdup?

According to our most recent InformationWeek Analytics reader poll on voice-over-Wi-Fi adoption, the No. 1 perceived barrier to deployment is a concern that reliability will not measure up to a traditional wired phone system. IT realizes that users will accept some network downtime and e-mail unavailability as normal, but let the phones go down and there's panic in the lunchroom. Also high on the list of worries are security, high systems cost, and a foggy ROI picture that is unlikely to clear until the legacy TDM PBX reaches the end of its life.

Still, it's not as if the status quo is any better. VoIP systems work well on wired networks, where quality of service can be provisioned with relative ease, but they also tie users to their desks. Cellular carriers do a much better job of enabling mobility, but the cost is high, data capacity is limited, and service availability inside buildings is often problematic.

A multimode smartphone that switches seamlessly between a WLAN and a cellular network, when Wi-Fi is unavailable, is a vast improvement, especially when you add enhanced mobility services such as location awareness, single-number access, presence, and a unified voice-mail box. In fact, the fixed-mobile convergence enabled by Vo-Fi is about as close to a sure-win technology as you'll find. Users get the best of all worlds, a fact reflected in readers' top perceived benefits: enhanced mobility, ability to work from remote sites while retaining a single phone number, and a reduction in telecom costs.

In today's tight economic climate, IT groups looking to sell Vo-Fi initiatives would do well to focus on savings in cellular charges--when employees have both a wired office line and a cell phone, it's not unusual for busy co-workers to routinely dial the cell phone. It's human nature to not want to waste time trying a landline when odds are that their quarry isn't sitting at her desk. And although our survey didn't focus exclusively on fixed-mobile convergence, we asked respondents for opinions about the productivity value to them personally in a dual-mode telephony system that let them use a single phone number for all business communication, regardless of physical location. Eighty-five percent indicated that such a system would be very or somewhat valuable.