There are a fair number of dual-mode mobile devices that let you run data over either a mobile WAN or a Wi-Fi LAN. There are plenty of mobile voice and data devices for doing both voice and data over a cellular network - and many let you do both in different frequencies in different parts of the world.You can get a BlackBerry now that also supports voice over the cellular service of your choice or wireless voice\/data over an 802.11b Wi-Fi network (but not both). Vonage will even sell you a phone to make VoIP calls from a Wi-Fi hot spot.But when it comes to finding a single handset that lets you talk both over an 802.11 wireless LAN and a cellular network, the pickings slim way down. By my count, the actual shipping choices on the market today boil down to these:* Symbol Technologies\u2019 high-end MC70, a rugged, multifunction device for highly mobile business users that was formally announced just last week;* The NEC N900iL, available from NTT DoCoMo for use with its service in Japan.Aside from likely being the first company to offer a hybrid device in North America, Symbol may also hold the distinction of producing the industry\u2019s first shipping 802.11a-capable VoIP handset: the MC70 supports voice and data over 802.11a\/b\/g networks as well as GSM and EDGE on the cellular side. 802.11a support could be important to the success of Wi-Fi voice for segregating voice channels and reducing interference.Avaya, Cisco, Motorola and Nokia are all reputed to be working on hybrid devices. The fruits of at least some of these efforts are expected as early as this quarter.Motorola, in fact, first announced the elusive CN620 - an enterprise-class handset described as supporting GSM and 802.11a - nearly three years ago in a joint effort with partners Avaya and WLAN maker Proxim. Though the CN620 has often been referred to in subsequent press releases and trade reports, I have not found evidence of it being purchasable.Now, the cost of the Windows Mobile 5.0-based Symbol device is steep (between $2,000 and $3,000). But it does a whole lot of stuff.It supports single-handed scanning, sports a push-to-talk button, is made rugged enough to withstand\u00a0frequent four-foot drops to concrete, is sealed so that medical personnel can wash and sterilize it, supports Bluetooth connections, and can be deployed worldwide.As of December, it was in the process of being certified for use with Avaya\u2019s Communication Manager IP PBX features and otherwise works with any Session Initiation Protocol (SIP)-compliant IP PBX, according to company officials.