Wi-Ex currently offers additional cellular signal boosters for the home, office and automobile, though they cost as much as $399. With the gadget that I tried, the main draw seems to be the price.

My main complaint with the zBoost zP: The signal boost is inconsistent. For instance, I tested the product using my Verizon LG VX8100 phone in a home office where I normally get one or two bars of service out of four. When I first set up zBoost zP, I didn't see any increase in cellular signal strength at all. After a few minutes, I noticed my one bar of service had increased to three. When I picked up the phone—while remaining within 6 feet of the antenna—the signal immediately dropped back down to one bar and then bounced back and forth between one and two. I walked around the antenna to see where the signal was strongest, and I eventually got the signal up to four bars, but couldn't get it to stay that way for more than a few seconds at a time.

I even saw my coverage bars drop down to zero without moving the phone more than a few inches from where it had three coverage bars a moment earlier. So while there's no doubt zBoost zP did indeed increase my cellular signal strength, what would truly be of value is a reliable increase.

The zBoost zP is dual band—it works with both the 800MHz and 1900MHz frequencies—and according to Wi-Ex, it's compatible with any cell phone, smartphone, PDA or wireless data card from all U.S. carriers, no matter what the wireless technology, except for Sprint Nextel's Integrated Digital Enhanced Network (iDEN). (iDEN is a wireless technology that enables users to make walkie-talkie calls via their mobile phones.) The company also offers another flavor of this gadget, the $99 zBoost zP YX100, a wired version that connects directly to your cell phone. Both versions of the product will be widely available on Sept. 15, Wi-Ex says.