Convergence--as in cellular-WiFi convergence--is gaining traction. While most businesses will wait until telecom carriers offer converged services to them, there is the option to buy gear to do convergence on your own:

• DiVitas Networks offers an on-premises appliance and a client installed on mobile devices which allows users to roam between carrier cellular networks, company WLANs and public WiFi hotspots. The appliance can serve as a PBX or can work with existing ones and it starts at $5,495.
• Siemens Communications this week will debut its HiPath MobileConnect, an appliance and mobile client system similar to DiVitas's. The appliance resides between a company's IP-PBX and WLAN, extending the office phone to a mobile device. Employees would appreciate the fact that they have one phone number and one voice mailbox, whether they're on the road or at their desks. Note that for the system to work, all employees would have to be given dual-mode mobile devices that can switch between cellular and WiFi networks. The Siemens client is available only on two mobile devices: the Symbian-based Nokia E60 and the Windows Mobile-based Fujitsu Pocket Loox. Siemens says it will support more devices when the product becomes available in the spring (DiVitas's client works with dual-mode phones, WiFi phones, standard cell phones, and softphones, and it's compatible with the Windows Mobile, Symbian, and Linux operating systems).

Businesses contemplating do-it-yourself convergence should make sure that their networks support VoWLANs, the Session Initiation Protocol, and Layer 3 roaming.

For more on do-it-yourself convergence:
-see details of DiVitas convergence solution [1]
-see more about Siemens HiPath MobileConnect [2]
-Elena Malykhina's Informationweek report [3]
-and Anony Savvas's Computerweekly report [4]