If carrier requests for proposals (RFPs) are any indication, several U.S. and European wireless carriers plan to deploy WiFi/cellular roaming services based on the UMA (Unlicensed Mobile Access) specification.

Initiated in January 2004, UMA was the brainchild of 14 carriers and hardware makers that wanted to extend GSM/GPRS voice and data services to unlicensed spectrum -- including both Bluetooth and WiFi. The team included hardware makers like Alcatel (NYSE: ALA; Paris: CGEP:PA), Ericsson AB (Nasdaq: ERIC), Nokia Corp. (NYSE: NOK), and Kineto Wireless Inc. , as well as carriers such as BT Group plc (NYSE: BT; London: BTA), Cingular Wireless , T-Mobile US Inc. , Telefónica Europe plc (O2) , and Rogers Wireless Communications Inc. (NYSE: RCN; Toronto: RCM).

In April 2005 the 3GPP (3rd Generation Partnership Project) took over the efforts of the UMA team. In terms of its ability to offer dual-mode roaming, UMA is considered a predecessor to using IMS (IP Multimedia Subsystem) technology to tie together cellular networks with unlicensed data systems such as WiFi.

In the last six months, "we've responded to more than 10, probably closer to 15, UMA-specific RFPs [requests for proposals] from carriers," says Steve Shaw, director of marketing at Kineto Wireless, which makes both core equipment and handset components for the UMA spec. "Stunningly enough, they actually call specifically for UMA."

BT launched UMA services in the fall of 2005. Analysts expect other carriers to follow suit by the end of 2006, including Telia Company and T-Mobile USA.

"We are on the verge of carrier deployments of UMA," writes Daryl Armstrong, an analyst with Citigroup , in a recent report. "As a rule, carriers that lack meaningful wireline assets seem to be most interested in deploying this technology."

To wit, T-Mobile US Inc. is expected to roll out UMA services within the next six months. The service makes sense for the carrier, which has both a cellular network and a wide deployment of WiFi hotspots in airport lounges and Starbucks coffee shops.

"I've been hearing back from a lot of people that they're very close to launching their service," said Kineto's Shaw. "We actually heard rumors that they'll be launching television ads about it." T-Mobile did not return a call for comment.

But not all of the original UMA participants plan to support it.

"Actually, we're going with IMS," said Ritch Blasi, a spokesman for Cingular Wireless. This is a change of heart for Cingular, which has voiced plans for UMA in the past. (See Cingular's Got Big FMC Plans.)

"We were looking at it, but when we explored the timing of both there was little difference in availability, and IMS is a better platform for convergence -- beyond cellular and WiFi," Blasi said in an email message to Light Reading. "We expect to have our first IMS application broadly available by the end of the year. That’s not necessarily this WiFi/cellular stuff, but an application that uses the IMS platform." (He declined to name the application.) On the handset side, though, UMA has a leg up. Nokia, Motorola, and Samsung all have announced phones that support UMA. According to Blasi, there are no IMS handsets.

— Carmen Nobel, Senior Editor, Light Reading