Sprint unveiled its much-anticipated femtocell service today, rolling out the fixed/mobile convergence technology in two markets: Indianapolis and Denver. The technology counters T-Mobile’s launch of unlicensed mobile access (UMA) technology, but offers an additional edge: the femtocell works like a miniature base station, using Sprint’s licensed spectrum meaning any Sprint customer can access the device.

Though not a nationwide launch like T-Mobile’s Hotspot @Home rollout, Sprint Airave service offers the same value proposition to customers: unlimited calling and better coverage at home. The femtocell like the UMA hotspot registers with the cellular network over the public Internet through a broadband connection. Unlike the UMA service, which uses Wi-Fi to tunnel the GSM signal back to the network, the Samsung-developed femtocell transmits and receives the same CDMA 1X signal communicating with a macro-base station, allowing Sprint essentially to extend its cellular network to millions of tiny micro-cells indoors.

That sort of scope, though, is far off as Sprint is starting slowly. Its femtocell launch is the first in the U.S. and the first commercial launch of the technology globally, and Sprint is the first to acknowledge kinks in the relatively new platform have to be worked out. A Sprint spokeswoman said today that Sprint will add one more market to the femtocell footprint by the end of the year, and the combined three markets would be used to determine details of a nationwide service.

“We’re still looking at things like pricing--that may change between now and a nationwide launch,” she said. Currently the service is priced at $15 a month for individuals and $30 a month for families, including unlimited long-distance calling. The service can support up to three calls simultaneously, and customers can allow other Sprint users to access the femtocell.

A critical difference between the T-Mobile and Sprint service is their focus. While T-Mobile is actively convincing their customers to drop their landlines and use the T-Mobile hotspot service, Sprint appears to be focusing more on coverage and cost-saving aspects of the service, said Peter Jarich, wireless research director for Current Analysis. Sprint doesn’t have the local exchange network that competitors Verizon Communications and AT&T own, but it does have interests in the wireline space, specifically with its deals with cable providers and its relationship with former LEC business Embarq.

Once Sprint’s femtocell network is fully ramped up, though, Airave could present a major challenge to T-Mobile’s Hotspot @Home. Airave requires no additional equipment purchase beyond the $50 Samsung femtocell unit itself, allowing customers to continue using any of its CDMA phones. T-Mobile meanwhile has to convince its customers to upgrade to Wi-Fi handsets, which represent only a small portion of the phones the carrier offers. Considerations of style or features might play into those decisions as well as cost.