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Meanwhile, others have begun devising cellphone ring-restriction
technology that is legal, at least until further notice. (The F.C.C.
maintains no regulations against cellphone-blocking techniques other
than jamming, but does not rule out the possibility that such
techniques could be scrutinized in the future.)
Bluelinx, based in Charlotte, N.C., is developing a system called
Q-Zone (the Q standing for quiet) that uses Bluetooth wireless
technology - in transmitters and imbedded into cellphones - to put
phones equipped with Q-Zone software into silent or vibrate mode
when they are taken into a specified zone.
Jeff Griffin, Bluelinx's president, said he was trying to sign up
wireless providers and establishments like cafes and theaters. He
said he hopes to start using the equipment in the next few years.
Unlike jammers, he said, his call-blocking system would be optional
for cellphone users, who could turn it on or off.
"I was at church some time ago and a lady's cellphone went off
and the entire church froze," Mr. Griffin said. "Meanwhile, she
couldn't find her phone and was so embarrassed. It's that kind of
circumstance we're trying to fix."
A similar system is being developed by Stefan Marti and Chris
Schmandt, researchers at the Massachusetts Institute of Technology's
Media Lab. Their project, called Autonomous Interactive
Intermediaries, uses technology like speech recognition to screen
calls to determine when a phone should ring, and even subtle, silent
visual cues to replace cellphone rings or vibrations - say, an
animatronic rabbit or parrot turning toward you in a room to signal
that you have a call.
Mr. Marti pointed out that the technology can always be
overridden by users. "People will get nervous if the cellphone
starts to make decisions by itself," he said. "It will take some
time for people to trust the technology," which could become
available within four years, he said.
Mr. Larson of the cellular industry group said that while the
industry objected to controls imposed on cellphone ringing, it did
not oppose measures left to the customers' discretion. "They are
certainly less odious than jammers," he said.
Another means of guarding against cellphone disturbance is the
use of detectors, sold legally in the United States and abroad, that
sound an alert when a cellphone is present. Zetron, a company in
Redmond, Wash., makes the Cellphone Detector Plus, a $449 receiver
that sounds an audio alert when it detects certain cellphone
frequencies. The model, about the size of a thermostat, flashes a
red light, beeps and plays a recording that urges people to turn
their phones off. The devices are useful for hospitals, said Vaughn
Entwistle, who edits Zetron's company newsletter.
An Israeli company, Netline, makes a detector called the Cellular
Activity Analyzer, a hand-held device that is used to monitor and
detect cellular communication activity in a given area. (It is
offered at www.netline.co.il or www.spyshops .ca for $2,500.) Other
smaller detector models include the RF Signal Detector from Suresafe
Technology, about the size of a beeper, which costs less than $100.
As with jammers, the larger the detector, the greater its range.
A different approach - by design or happenstance, but altogether
legal - is to block cellphone signals through construction
techniques. (An F.C.C. spokeswoman said the commission had no
regulations dealing with building materials.) Like most
cellphone-blocking methods, many of these ideas were developed long
ago for military and espionage purposes, said Bill Sewell, senior
vice president of DMJM Technology, who has spent years designing
radio-secure areas for the United States government.
Mr. Sewell said the methods used by his firm are simple: metal
mesh screens tuned to the frequencies of radio waves are mounted
inside the wall. They are also inexpensive, at about $15 a square
foot, he said.
Like Mr. Sewell, Deborah Chung, the Niagara Mohawk professor of
materials research at the State University at Buffalo, has developed
construction materials that block radio waves. Dr. Chung's "smart
concrete" contains electrically conductive mixtures, like metal or
carbon particles, that provide electromagnetic interference.
Her structures are designed for the military and hospitals, she
said, but they could be used in other structures to keep cellphone
users away. "It certainly would work," she said. "On the other hand,
they might not be able to watch TV inside."
Some buildings have the blessing or curse of being
cellphone-proof by accident, thanks to heavy walls. An example is
the Frederick P. Rose Hall, the new home of Jazz at Lincoln Center,
which is scheduled to open in October at Columbus Circle in
Manhattan. The building is designed as a box within a box, with two
sets of walls - the auditorium wall and a separate lobby wall - to
prevent sound from seeping in. This double-thick construction, said
Walter Thinnes, the vice president of Rose Hall, prevents cellphones
from working in the auditorium.
"This is an unplanned helping hand," Mr. Thinnes said.
Without such help, there is a last resort: personal
responsibility. "There are always going to be rude people," Mr.
Larson said. "We just hope they will learn to turn their cellphones
off at the right time."