A self help way to stop people from talking on cell phones in public?

Apparently signal jamming is illegal, but I am sure that a lot of people appreciate this crime occurring. That said, there really isn't an externality problem here because the owner of the bus or train bears the cost of deciding whether people should be able to use their cell phones in public. If people value using their cell phones less than the other passengers dislike them being used, the owner of the transportation will make the most money by not allowing them to be used. From CNET:

It might be the 7:30 a.m. bus and you might be semi-comatose from a long night of self-anesthesia, but some people do insist on talking into their cell phones about last night's cabbage stew or a lover who smells of cadaver.
You can tell them to be quiet. But this, too might be ignored. So one rider in Philadelphia decided he'd use an alternative method: he says he simply jams all cell phones on his bus.
I know many will be grateful to NBC 10 in Philadelphia for discovering this remarkably simple method at achieving world peace.
"I guess I'm taking the law into my own hands. And, quite frankly, I'm proud of it," the man told NBC.
The man--whose name is Eric--said he found people talking on their cell phones during rides on public transport both irritating and rude. (Oh, but surely they're interesting, once in a while.)
He said he used a cell phone jammer that he bought online. . . .