Cellphone Jammers Gaining In Popularity

As cellphone use has skyrocketed, making it hard to avoid hearing half a conversation in many public places, a small but growing band of rebels is turning to a blunt countermeasure: the cellphone jammer, a pocket-sized gadget that renders nearby mobile devices impotent.

The technology is not new, but overseas exporters of jammers say demand is rising and they are sending hundreds of them a month into the United States — prompting scrutiny from federal regulators and new concern from the cellphone industry. The buyers include owners of cafes and hair salons, hoteliers, public speakers, theater operators, bus drivers and, increasingly, commuters on public transportation.

The jamming technology works by sending out a radio signal so powerful that phones are overwhelmed and cannot communicate with cell towers. The range varies from several feet to several yards, and the devices cost from $50 to several hundred dollars. Larger models can be left on to create a no-call zone. Using the jammers is illegal in the United States. The radio frequencies used by cellphone carriers are protected, just like those used by television and radio broadcasters.

The Federal Communication Commission says people who use cellphone jammers could be fined up to $11,000 for a first offense. Its enforcement bureau has prosecuted a handful of American companies for distributing the gadgets — and it also pursues their users.

Investigators from the F.C.C. and Verizon Wireless visited an upscale restaurant in Maryland this year acting on suspicions of cell phone jamming. The owner, who declined to be named in the NYT article, said he bought a powerful jammer for $1,000 because he was tired of his employees focusing on their phones rather than customers. The owner said the F.C.C. investigator hung around for a week, using special equipment designed to detect jammers. But the owner had turned his off. The Verizon investigator was similarly unsuccessful. “He went to everyone in town and gave them his number and said if they were having trouble, they should call him right away,” the owner said. He said he has since stopped using the jammer.

Cellphone carriers pay tens of billions of dollars to lease frequencies from the government with an understanding that others will not interfere with their signals. And there are other costs on top of that. Verizon Wireless, for example, spends $6.5 billion a year to build and maintain its network.

Gary, a therapist in Ohio who also declined to give his last name, citing the illegality of the devices, says jamming is necessary to do his job effectively. Gary said phone calls interrupted therapy all the time, despite a no-phones policy. Four months ago, he paid $200 for a jammer, which he placed surreptitiously on one side of the room. He tells patients that if they are expecting an emergency call, they should give out the front desk’s number. He has not told them about the jammer.