With a nod to the 3GSM conference in Barcelona last month, it seems appropriate to talk a little about convergence.

An emerging 3rd Generation Partnership Project (3GPP) standard called Unlicensed Mobile Access (UMA). UMA, along with other industry initiatives, seeks to IP-enable cellular networks as a way to merge them with fixed IP networks and wireless LANs.

The availability of a UMA-enabled phone was one in a litany of announcements made by wireless behemoth Motorola, which introduced its dual-mode Wi-Fi/UMA A910 phone in Barcelona, for use with the nascent BT Fusion converged service offering in the UK. Using the handset, subscribers to the service can make calls at their fixed-line phone rates when away from the home or office by connecting to BT's public Wi-Fi access network called BT Openzone.

UMA, currently a consumer-oriented endeavor that could spill over into the business market, takes a cellular-centric approach to converging phone calls and providing single-phone-number service. The idea is to keep calls under the carrier's control, but to offer a better calling rate when calls are on the enterprise's Wi-Fi network.

Why not use SIP?
A similar but competing effort, called MobileIGNITE and initiated by BridgePort Networks (read about it here), also takes a cellular-centric approach, but leverages the Session Initiation Protocol to enable standard, PBX-like features to be hosted in the carrier network.

"Entities are battling for who owns the talk time we have in the office or home," says Steve Shaw, director of marketing at Kineto Wireless, the champion that founded the UMA effort.

Indeed, the Seamless Converged Communication Across Network (SCCAN) Forum takes an enterprise-centric approach to convergence. SCCAN was originally formed by Avaya, Motorola and Proxim Wireless and has since added Meru Networks and Chantry Networks (now owned by Siemens) to the party. The approach here is to install a piece of intelligent customer premises equipment (such as the Motorola Wireless Services Manager) at the edge of the enterprise to handle the Wi-Fi-to-cellular handoff. This approach extends PBX functionality to mobile employees in and out of the enterprise and enables enterprises to pay no cell charges when on their own Wi-Fi LANs.

Motorola says its PBX-centric solution with Avaya and Proxim - dubbed Seamless Enterprise Mobility - is in about a half-dozen trials around the globe. The company says it is confident it will soon be able to clarify when the setup will be commercially available.