Carriers worldwide have begun to unite two previously disparate broadband access technologies — Wi-Fi and mobile — that once seemed to be on a competitive collision course toward one another. Wireline telcos, mobile carriers, voice-over-IP service providers and even cable TV companies have realized the potential benefits of matching the increasing Wi-Fi coverage in residences, enterprises and public hot spots and hot zones with the mobile network coverage already prevalent just about everywhere else to create seamless wireless voice and data services.

They were coaxed toward that realization by at least three market factors — the broad availability of Wi-Fi coverage, the consistently increasing number of mobile minutes of usage and the trend toward wireless replacement of traditional wireline services.

To answer this call for convergence, a growing number of carriers are turning to deploy a new wireless access technology based on industry standards that renders the method of network access — Wi-Fi or mobile — irrelevant to users. If you think that sounds a lot like the IP multimedia subsystem (IMS) architecture, you're right — it does sound like IMS. But, it is not IMS that more and more carriers are leaning on right now to create new convergent service. It's actually unlicensed mobile access (UMA) technology, a solution with the backing of a large consortium of carriers and vendors that is now part of the 3GPP standards family and has had a much faster, more direct trajectory to market than IMS is expected to have.

In conception, fixed/mobile convergence (FMC) technologies are nothing new. Virtually every mobile infrastructure vendor has experimented with some type of FMC technology before — Ericsson's past Mobile@Home solution was one recent example, according to Bengt Nordstrom, senior analyst at Northstream, a subsidiary of U.S. research firm inCode Wireless, that recently completed a comprehensive report on the UMA market.

However, UMA is the first of those technologies to have gained fairly broad support from a variety of different wireless industry companies. The foundation technology for UMA was developed by Kineto Wireless, a 4-year-old company based in Milpitas, Calif. Kineto initially called its product — a network controller designed to transport GSM/GPRS signaling and call traffic securely over IP — the mobile-over-WLAN solution.

However, by January 2004, the wireless industry was seriously considering technology options that could give the industry competitive leverage to conquer one of its final market frontiers — the pervasive in-building coverage required to provide a quality wireless service inside customers' homes and workplaces. Kineto by then had gained significant carrier interest in its technology, but not surprisingly, the industry was hungry for a widely applicable standard. So that month, Kineto joined with 13 other companies, including carriers BT, Cingular Wireless and T-Mobile, and major equipment and handset vendors Ericsson, Motorola and Nokia to create a UMA consortium.

The name unlicensed mobile access was chosen to describe how an open set of specifications would be used to extend mobile voice and data services over any wireless technology using unlicensed frequencies. That includes not only 802.11 Wi-Fi but also potentially Bluetooth, current broadband wireless access gear and even future access equipment based on 802.16 WiMAX technology.

The very early criticism of the UMA group's effort was that it wasn't part of the overall 3GPP standards effort, but in June 2004, it was introduced to the 3GPP Technical Specification Group and was standardized this past April under the title “Generic Standard to A/Gb interface” and is part of the 3GPP Release 6 document.

Contrast that rapid timeline to standardization with the journey the IMS currently is taking: Portions of the IMS standard are included in 3GPP Release 6 and Release 7, but some details of the IMS standard remain to be defined.

“Right now, UMA is the only 3GPP standard allowing extension of mobile services over other kinds of fixed access infrastructures,” said Steven Shaw, director of marketing for Kineto Wireless.

Since April, several vendors have announced products based on UMA and have developed partnerships to address the market opportunity. Also, carriers have gradually begun to reveal their plans. The most publicized project among them has been BT's Bluephone project, which was launched commercially on a limited basis under the service brand BT Fusion this past June.

Fusion is the only commercial UMA service so far, but several more are expected to launch within the next year. France Telecom will launch its Homezone UMA-based service next year, Finnish operator Saunalahti has confirmed plans for commercial launch and, according to Swedish magazine Ny Teknik, Teliasonera will begun launching UMA in 2006, in a rollout that will encompass the Nordic countries and the Baltic states over the next three years. In North America, Cingular and Canadian carrier Rogers Wireless both have announced trials of the technology.

“North America will be the largest and one of the first markets to launch UMA services,” said Monica Paolini, principal at Senza Fili Consulting and author of recent UMA research. “Mobile operators see cellular and Wi-Fi convergence as a cost-effective way to improve residential coverage, increase ARPU and keep churn down.”

“There are a number of trials now, and not just in Europe — every North American GSM operator has an RFP out right now for UMA,” Kineto's Shaw added. “The whole telecom industry has tied it's future to IP, and UMA leverages IP.”