A weak signal at home or at the office can slow down your service or just makes it impossible to get a phone call. But now there's a new device that will boost your signal and even help 911 operators find your house in an emergency.

"Oh, it's night and day difference," said Jessica Garrett, who uses a signal booster from Sprint. "I don't think enough people do know about it and they should."

The device -- about the size of a wireless router -- acts like her own personal cellphone tower. You plug it into a power outlet and high-speed Internet. Then, your phone connects to your booster while at home, rather than a cellphone tower outside.

The booster then sends your phone signal through your home Internet, all the way to your cellphone network.

"Whenever it's on it boosts our signal, our calls never get dropped, our Internet goes faster on our phones," Garrett said. "It's extremely helpful, I don't know what we'd do without it."

Garrett's booster was put to the test. She had a full five bars when it was plugged in. When unplugged, her phone dropped down to two bars.

The cellphone boosters can also help police, who are getting more cellphone calls than ever.

With enhanced 911 services, a dispatcher sees your exact home address when calling 911 from a regular landline. Calling 911 from a cellphone does not work that way.

"With the cellphone it pings off several towers, so it gives us a general location but without having a person stay on the line and tell us exactly where they are, we would be driving around, looking for a person on the cellphone," Bologna said.

The cellphone booster devices can be programmed to provide an exact address to a dispatcher -- just like a landline. It could add crucial seconds to response times. AT&T programs its boosters to tell dispatchers your exact address.

"911 calls placed over your 3G MicroCell will send the address you provide in your online registration to the emergency response center responsible for sending first responders (i.e. police, medical assistance or fire) to your location," AT&T said in its frequently asked questions section for its MicroCell.

There are drawbacks, however.

"Your 3G MicroCell needs electrical power and Internet service to work. If a failure happens, all calls placed including 911 will NOT be connected through your 3G MicroCell," AT&T said. During such a failure, the calls would go through the normal cell towers.

Sprint said its booster called the Airave helps dispatchers find you in a different way.

"An Airave is considered an extension of our wireless network, so a 911 dispatcher will be able to locate a caller based on the nearest cell tower, and if applicable, can re-bid their system for longitude and latitude of te exact location. This depends on whether that PSAP has been fully integrated for e911 services," a Sprint spokesperson said.

A Verizon spokesman was still working to confirm exactly how its booster called a network extender helped dispatchers find callers.

A review of several cellphone company websites shows signal boosters range in price from about $100 to $250, but Garrett was able to get hers from Sprint for free. A Sprint spokesperson confirmed that a decision to give a free device to a customer is made on a case by case basis. In other words, it can't hurt to ask.

The devices can be set up at both home and work. They're popular in large buildings with barriers blocking signal and in newer subdivisions near the edge of town, like where Garrett lives. She's even ditched her landline altogether.

"Technologies tend to sometimes be very unreliable, but with a booster like that, it's helping technology be more reliable," she said.

Links to more info on boosters:

--AT&T

--Sprint

--Verizon