No service? Maybe you've been zapped by a mobile phone jammer.

A Philadelphia man has stirred up controversy after he frequently used a device on a public bus to create a cell phone dead zone.

A reporter for NBC10 in Philadelphia recently tracked down the man, who was using a mobile phone jammer on the bus to block riders' cell phone reception. His reason — he didn't want to listen to other people's phone conversations. He says he turns on the illegal device whenever other passengers talk too loud and bother him.

The man, identified as Eric, told NBC reporters: “I guess I’m taking the law into my own hands, and quite frankly, I’m proud of it.”

A portable mobile phone signal jammer typically looks similar to a walkie-talkie and has multiple antennae pointing out of the top of the device. Its job is to jam, block or interfere with wireless communication including Wi-Fi, cell phone reception, and GPS and police radar.