It\u2019s an interesting proposition, and one that could have a ripple effect throughout the industry: Combine the success of wireless LANs, the success of mobile phones and the promise of voice over IP.Putting voice over WLANs could be a bit scary. WLANs are popular because of their flexibility, yet they also raise security questions. Add voice - something that requires quality-of-service controls to make sure the voice packets get through - and you have a whole new can of worms to contend with.WLAN phones aren\u2019t yet widely available, but they are on the rise. Synergy Research Group has been tracking just two companies in the segment, SpectraLink and Symbol Technologies, since 2001. SpectraLink owns roughly two-thirds of the market - which isn\u2019t that big, relatively speaking, at $15 million last year.Cisco has indicated that it will make a WLAN telephone available next month. It sees applications for such technology mainly in places where employees need to move around a site during their day, like retail stores.However, with the emergence of WLAN hot spots around the country and around the world, you have to wonder whether we are headed towards WLAN technology being used for phones more broadly.There are several obstacles to that, of course. The hot spots would have to be set up for phones, and the phones would need to be enabled to switch between WLAN use and cell use. But the possibilities are intriguing.