NEW YORK (TheStreet) -- What if I told you there was a device that strengthened cellphone signals so your phone worked reliably inside your house -- upstairs, downstairs and even in the basement?Interested? Well, what I told you, sorry, you can't have it no matter how much money you throw at the companies offering it? That's what is happening all over the country. The device is a tiny cell tower called a femtocell, named for the mathematical term for one-quadrillionth the size of a unit. It can improve indoor cell signals dramatically. Unlike signal boosters, which take and amplify the stronger outdoor signal indoors, femtocells work even with terrible outdoor signal. They use a home's broadband Internet and a GPS signal to communicate with the nearest mother tower. Indoors, these petite, portable mini towers broadcast a cellular signal -- not Wi-Fi -- of several thousand square feet so phones remain connected to a cellular network. But today, only customers of AT&T ( T - Get Report), Sprint ( S - Get Report) and Verizon ( VZ - Get Report) can get one for about $100 to $300. One regional U.S. carrier, Mosaic Telecom in Wisconsin, also offers one for $50. The wireless carriers may toss one in for free, especially if you threaten to leave due to poor indoor reception. Everyone else? Too bad. T-Mobile, MetroPCS and most other carriers don't offer it. Even some customers of the ones that do such as Sprint-owned Virgin Wireless and Boost Mobile -- are out of luck. Granted, the big three make up about 80% of the U.S. wireless population but it's often the customers of smaller companies that could use the boost. "Coverage is the main reason why consumers churn and leave their existing operator," said Andy Germano, vice chairman of the Small Cell Forum, an organization promoting the development of these mini cell towers. "Giving someone a low-cost femtocell to address that issue is almost a no-brainer." The reason why femtocells are not available in stores like Best Buy ( BBY - Get Report) or from every wireless carrier is the devices operate on licensed wireless spectrum, the same spectrum that companies like Verizon, AT&T and Sprint pay billions of dollars to the government. Each femtocell must be registered and approved by its cellphone carrier before it starts working for you.
"Although we continue to review customer premise equipment solutions like femtocells and repeaters, we have no plans to deliver a femtocell product. The beauty of Wi-Fi Calling is that it turns any open Wi-Fi access point into an instant coverage area for Wi-Fi Calling enabled handsets. So, while femtocells benefit one location, a Wi-Fi Calling customer sees benefit in multiple locations."Femtocells, which aren't perfect but get a steady stream of superior reviews, started showing up in the U.S. in 2007. But even with the promise of better indoor Internet, high prices kept customers away. Some customers argued they shouldn't have to pay extra for a service for which they already pay. Last year, the three carriers began giving devices away for free to those complaining of poor indoor service. This year, approximately five million femtocell devices will be sold worldwide, estimates ABI Research. "In the next five years, we think that number is going to grow 10 times," said Hoffman, who got his own AT&T femtocell a few years ago and watched his 1-to-2 bar reception go to full bars in his house. But five million femtocells a year pales in comparison to the 1.9 billion cellphones forecast to be sold this year by Gartner, a research and advisory firm. Hoffman believes many people don't know or understand the purpose of a femtocell. "Most people I talk to about it say, 'Why would I want that?' It's another box in the house. When cellphone coverage isn't good in the house, it's the cellphone company's fault," he said. "Generally speaking, when you can't get good signal inside, you switch carriers."