No service? Maybe you got tapped by a cell phone jammer.A Philadelphia man sparked controversy after frequently using a device on a public bus to create a cell phone dead zone.

A reporter from NBC10 in Philadelphia recently tracked down the man who used a cell phone jammer on the bus to block drivers' cell phone reception. His reason - he didn't want to hear other people's phone calls. He says he will turn on the illegal device when other passengers speak too loudly and disturb him.

The man identified as Eric told NBC reporters, "I think I take the law into my own hands, and frankly, I'm proud of it."

A jammer is usually similar to a walkie-talkie and has multiple antennas that point at the top of the device. Its job is to disrupt, block or interfere with wireless communication including WiFi, cell phone reception, GPS and police radar.

Section 302 (b) of the Communications Act of 1934 [PDF] prohibits the "marketing, sale or use" of jammers. The federal government and companies tasked with federal work normally related to internal security are only allowed to use jammers. Like many uninformed people who have jammers, Eric believed that jamming was legal.

"We are concerned about the reported incident and are investigating it," said Michelle Ellison, chief of the enforcement bureau for the Federal Communication Commission, in an email regarding the incident in Philadelphia.

While the device is illegal, bus drivers aren't the only ones trying to silence people with a jammer. The FCC has investigated the use of cell phone jammers in schools and theaters. Some administrators seem to believe that a cell phone jammer would be an easy way to prevent students from using their cell phones during school hours. Cell phone jammers are useful in theaters to prevent people from using shows during shows.

"While some people who use jammers think they are just silencing loud conversations or turning off unwanted GPS tracking, they could also prevent a frightened teenage boy from calling 911, an elderly person from making an urgent call to a doctor, or an emergency Rescue teams from you are looking for the location of a seriously injured person, "said Ellison. "The price of a person's moment of peace or privacy could very well be the safety and well-being of others."

Jammers are a problem because they block license sequences that do not belong to the jammer and it is illegal to jam license sequences. Jammers can block signals within a few tens to hundreds of feet. The FCC is mostly concerned with jammers that block emergency responders from communicating with callers.

People in the US usually buy jammers online. The FCC is working to prevent other countries from selling and shipping jammers to America, but some jammers are slipping through the mail. Cell phone jammers are also not permitted in the UK, Canada, Switzerland and Australia.

In October 2011, the FCC warned 20 online retailers that it was illegal to sell and market signal jamming device to Americans. However, with a quick Google search, an American can order a cell phone jammer online.

"Our actions should send a strong message to signal jamming retailers that we will not tolerate continued violations of federal law," Ellison said in a press release.

The US tries to keep jammers out, but the network blockers can be made and exported in the US. The FCC said they are unaware of any violations in the manufacture of cell phone jammers in the United States.