Alcatel and Nortel are both promoting voice over WLAN systems by reselling WLAN equipment from Airespace and handsets from SpectraLink: Cisco started selling voice over WLAN handsets last year and ironically it appears that move is actually good news for SpectraLink, which has been making such phones for many years. That's because Cisco competitors like Alcatel and Nortel need to sell voice over WLAN systems to customers but certainly won't sell Cisco phones. Instead they'll use SpectraLink's.
This story included some interesting figures form Forrester Research about WLANs. The study found that 20 percent of companies have or are in the process of building WLANs. About 15 percent of companies said they had completed or were in the process of rolling out voice over IP systems, but the story doesn't distinguish if that refers to voice over WLANs or voice on regular wired phones. I suspect that the companies that have deployed voice over WLANs are concentrated in certain market segments like factories or warehouses. It's likely that there are few companies in standard offices using voice over WLAN as the benefits are less clear and because building a WLAN to support voice is a more challenging proposition than constructing a WLAN just for data.