Smartphones are capable of many tricks these days -- thanks to an abundance of apps, Internet connectivity and embedded MP3 players and cameras -- but all the bells and whistles don t mean a thing if you can t get a signal.

The average consumer spends roughly $70 a month for cellphone service, according to market researcher Nielsen. For that kind of money, the ability to make clear, consistent connections at home, in the office and on the road seems perfectly reasonable.

most notably, Verizon (VZ) and AT&T (T) ) duke it out in commercials over who has the best coverage, fastest network and hottest phones, companies at the International Consumer Electronics Show in Las Vegas are looking at the problem from a different perspective: You have a phone you like, a network you don t, and a contract or other factor impeding you from switching.

Enter the signal booster, which uses a more powerful antenna that makers say captures and amplifies weak signals cellphones can't pick up on their own. Other versions, including AT&T's MicroCell, can piggyback on your home Internet connection to create a signal instead. The pitch to consumers from companies including AT&T and CelLynx: The antenna reduces dropped calls, improves connections and speeds up 3G transmission. What's more, they say, users get better value for cellphone and data plans, and extend their phone's battery power since the battery won't need to constantly search for a signal.

Boosters, of course, aren't magic bullets. Those that rely on capturing weak signals can't materialize a signal where there's none whatsoever. They may need to be paired with a wireless earpiece, since phones must usually remain in a docking station or heavy cradle to sync. Boosters can also be expensive, with most priced at $150 and up.

"I'd be cautious about relying on them," says Andrew Eisner, the director of content for Retrevo.com, an online electronics marketplace that offers user manuals and consumer reviews. "It's not a sure thing you'll get coverage where you didn't before." Check the return policies before you buy to ensure you have several weeks to test the device.

Here, the latest offerings presented at CES.

CelLynx 5BARz Road Warrior

$299

An honoree for the International CES Innovations 2010 Design and Engineering Awards, the CelLynx (CYNX) device is designed to work with all national cellphone carriers and most wireless devices, including cellphones and data-enabled laptops. Adaptors let you plug in at electrical outlets and car cigarette adaptors. There s no installation: just plug in the booster, dock your phone and you re good to go. (A side deal: authorized retailer eCost.com offers the Road Warrior for $240, a 20% discount.)

The Sleek from Wilson Electronics

$129

The new Sleek is the cheapest in Wilson s line of cellphone boosters. The slim cradle lets users choose whether to hold their phone to talk or use a wireless earpiece, says a spokesman. Adjustable arms fit the device to most cellphone models, and a power port charges your docked phone. The plug-n-play booster should work with all major carriers except Nextel. It s designed for use with a car cigarette adaptor, but the company also plans to release a home adaptor kit (price TBA).

zBoost by Wi-Ex.com

$119 to $499

Another Innovations 2010 Design and Engineering Awards honoree, Wi-Ex offers a range of boosters for use at home or while traveling. A spokeswoman says the products work well for city dwellers: The zBoost-ONE ($299, for Sprint and Metro PCS phones) has no external antenna, allowing more flexibility in placement. Smaller zBoost zP models ($119 and $169, for phones on 800 and 1900 MHz frequencies) have a short range of about six feet, and are meant for dorms, hotel rooms and small living spaces.