Meanwhile, T-Mobile is running a similar pilot program, HotSpot @Home, which also allows customers to pay a flat fee to get unlimited calling within the home. Instead of using femtocells that use a carrier's own licensed spectrum, however, HotSpot @Home uses the unlicensed Wi-Fi spectrum.
This approach is cheaper to deploy but requires special dual-mode handsets, whereas Sprint's approach gives unlimited calling to all Sprint-compatible phones while forgoing the ubiquitous Wi-Fi spectrum.
Mike Jude, a senior analyst with Nemertes Research, said that these deployments appear to be going well so far, but carriers are still trying to define the demographic sweet spot for the technology.
"I think we're in the early adoption phase right now," he said. "They're just trying to figure out how it resonates."
Right now, the most likely femtocell positioning appears to be as a landline replacement: For a small additional fee, cell phones can gain unlimited, clear calling at home, which could be an appealing prospect to millennials who have long ditched traditional landlines.
A recent report published by Infonetics suggested that femtocells could be extremely fertile ground to test. The report stated that -- if scalability, management and other issues were resolved -- the femtocell market could grow to $1.5 billion by 2011.
"I think there's a demographic, people just out of college, who are very comfortable with 21st century technology, who would look at that and say that's cool," Jude said. "There might be a certain demographic that doesn't want another emitter in their house."
Today, the femtocell focus is squarely on consumer early adopters, with little movement in the enterprise -- a focus Jude said he expects to change over time. One of the big barriers? The wireless management needed when phones hand off between multiple femtocells to ensure seamless calls.
It's a tricky technical challenge, but it's not an insurmountable obstacle by any means. Many of the same problems have already been addressed in various ways by wireless networking vendors and cellular equipment providers, but the consumer market is an attractive testing ground before enterprises invest in the technology.