rise apartments these days? Five bars on your cellphone. The Wi-Ex zBoost YX510 can help improve coverage at home or the office. The Time Warner Center in Manhattan, for example, has seamless cellular coverage throughout the building because of special antennas and repeaters that cost its owners about $1,000 each. The system ensures clear calls everywhere, from boiler room to penthouse. But you don't have to be a master of the universe to get good cellphone reception. Carriers and electronics manufacturers are now offering ways to make clear calls anywhere in your house, using devices that route calls through your home Internet connection or pump up the weak signals. “Because more and more people are not taking landline telephones anymore, adding a signal booster is becoming much more popular,” said Richard Holtz, president of Infinisys in Daytona Beach, Fla. His firm plans the placement of cellular boosters in high-rise buildings, dorms and offices. “People are expecting perfect coverage everywhere,” Mr. Holtz said, pointing out that being indoors or outdoors can make a big difference in call quality. Many things get in the way of wireless signals. Trees and intervening buildings can degrade the signal from the cell tower, while brick walls and wallboard supports can block them completely. Sometimes many obstacles will conspire to create a “dead zone” of dropped and missed calls. One solution to these problems is a device called a femtocell, which is sold only by cellphone carriers. These Internet-connected boxes act as tiny cell towers in your home or allow you to make calls over your local Wi-Fi network. T-Mobile's offering, called HotSpot @Home, uses specially outfitted phones to send calls through your Internet connection over a $30 router. The service costs $10 a month on top of your regular bill and allows unlimited calls between phones in the United States and Wi-Fi hotspots anywhere in the world. Once you leave the hotspot, the cellular wireless network takes over. T-Mobile now has three Hot Spot @Home compatible phones, which cost no more than regular phones, and will release 10 more this summer. The company says it has trained its sales force to work with potential customers who may not be aware that their homes or offices are in a dead zone. “One of the first things our reps are trained to do is a personal coverage check to see, real time, what you can expect the coverage to be at your home,” said Britt Wehrman, director of product development at T-Mobile. (You can check your own coverage at www.t-mobile.com/coverage.) Verizon Wireless, AT&T Wireless and Sprint are all looking at femtocell products as well. Sprint is running trials in Denver, Indianapolis and Nashville with its own hardware. A Verizon spokesman, John Czwartacki, said the company was still evaluating the technology. These carriers are likely to use a different kind of device that mimics a cell tower, avoiding the need to use special phones and Wi-Fi. Hassan Ahmed, founder of Sonus Networks, a company that makes femtocells, said he believed that almost all of the carriers would add the technology to their product lines. “I get great cellphone coverage around my house, and I get great Internet inside my house with DSL,” Mr. Ahmed said. “However, when I'm in my house I can't get any bars. A femtocell device is a win-win: it gives the carrier a way to improve their infrastructure and it gives me full bars.” If you can't wait for your carrier to start selling femtocells, you might try a cellular repeater, also known as a booster. This device picks up cellular signals from outside and “repeats” them inside the house, increasing their strength. The signals from your phone are then broadcast back outside via the repeater, ensuring that both sides of the conversation are clear. Wi-Ex (www.wi-ex.com) makes several cellphone boosters including the zBoost zP YX300 ($169), which covers a small area, and the zBoost YX510 ($400), a larger device for homes or offices that improves coverage over a 3,000-foot zone. These devices have an internal antenna and an external one that can be mounted on a window or outside wall. Because of the way the device rebroadcasts the signal, the external antenna must be about five feet away from the base station. If the antennas are too close, the signals begin to echo each other, reducing range and reception or even blocking the signal. Another new product, the Cell Ranger Stix, is a portable booster that is powered by your car's cigarette lighter. Available at www.getcellranger.com for $129, the device has an external antenna and a 15-foot cable. You attach the antenna to the back of the car and then run the cable through to the cigarette lighter. While it won't help in areas with no cell reception at all, it could be useful in areas where signals are too weak to pass through a car's glass and metal. Booster shoppers need to know that not all boosters work with all carriers, because the carriers use different frequencies and technologies to transmit calls. T-Mobile and AT&T use something called GSM, while Verizon and Sprint use CDMA. The booster, unless it is a universal model, must be compatible with the carrier you use regularly. The presence of boosters on frequencies that belong to the carriers has made them somewhat controversial. The Federal Communications Commission certifies the devices for some purposes, but they recommend contacting your carrier before installing one. If a person is interested in improving coverage with a booster, “we would encourage that person to first work with his or her wireless carrier to identify a certified device that the carrier also approves of before installing it and using it on the network,” said Robert Kenny, a spokesman for the F.C.C. Those in the industry say newer models don't have the blocking problem. Sina Khanifar, one of the owners of RepeaterStore.com, said a newer booster will amplify only the signals that are being used, preventing it from overwhelming and degrading the cell tower signal. “Because they scan the band, they get lots of additional information about the signal,” Mr. Khanifar said. Of course, boosters require you to shell out your own money to improve a service you are already paying for. Pestering your carrier to upgrade its network is a cheaper — but slower — approach. – NYT __
