Active cell phone blocking in private buildings?

I was in a medical office today where my cell phone got 3bars from the local tower. However, all apps and the browser said ’ no internet connection. I got intrrnet again directly outside the building as soon as i got away from th glass doors. Do people actively block cell signals for their convenience? Without notice? Is this a thing?

Seems bad. Coud make people miss emergency calls, not be able to call 911, etc. Is this legal in the US?

It wasn’t being actively blocked, you were just getting bad reception in the building.
To the best of my knowledge, it’s not legal to jam your cell phone, with or without your permission.

If you checked wifi, you might find that they provide an internet connection for you, specifically because of the poor reception. I know all the doctor’s office I go to do. Many big stores (ie Target) do as well, for the same reason.


Don’t the bars just mean phone reception? Did you try to make a call? My phone (admittedly not the latest and greatest) has a separate logo for 4gLTE (or slower). I’m guessing you probably had phone service but the building structure was blocking the data signal.

That’d be my guess, as well. Heck, the building where my doctor’s office is located is so bad in this regard that even getting enough of a signal to make a phone call or send a text is iffy.

It is illegal to jam a moderated signal in the US.

I feel like it should be legal to switch your phone to vibrate in certain places like theaters, or restaurants.

And you’re not even a Moderator!

Is your phone set up to grab wifi when it can? Because, if it got on the office network, it could have gotten stuck in molasses or blocking software so that it could not really do anything but was not smart enough to get off the useless wifi and back on the cell network.

It is, however, legal to physically shield buildings. There are contractors who do this kind of work. Expensive, though, and it’s usually places like medical clinics that do this.

And there are also some buildings which aren’t specifically designed to block signals, but end up doing a pretty good job of it anyway (especially buildings with few windows, and either lots of metal in the walls, or just really thick walls).

My understanding is if your phone had three bars then the signal wasn’t blocked. Your data would come with those bars. The problem was with your carrier.

:confused: It is legal to do this, I do it all the time with my phone.

On my phone, and the ones I’ve had previously, the bars show the signal strength of the main signal, but the quality of the data reception is a separate icon showing whether I’m getting 4G, 3G or poorer. There is some correlation, but depending on the kind of system you are on you can have full bars from “old fashioned” cell reception, using older frequencies that penetrate buildings better and need fewer towers, and no data reception on the newer frequencies.

If that is not the kind of cell service the OP is getting it would also be impossible to jam their internet and not their call service, so there’s that.

I think Grrr! means that the theater/restaurant/etc. would unilaterally change your phone setting to vibrate-only without you choosing it. Which sounds like a supremely bad idea: if the place I’m in can change my phone settings without my permission, then what the hell else could they do to my phone?:smack:

Personally I think creating phones with this being an externally accessible option for a kind of bluetooth/NFC triggered “audible ring supressor” would actually be a pretty cool thing. If the system hits it puts phone in vibrate for 10 minutes. Signal generator pops once every 5 minutes or so, so once you leave the place, phone goes back to normal in 5-10 min on its own.

IIRC cellphone wavelengths are about a foot and a half to about 6 inches. I would assume a metal mesh for stucco might make an effective block, so add in a metal roof and some metallic window tint and you could get a fairly effective radio-proofing.

My experience in movie theaters is that that the problem isn’t noise (ringtones, text message alerts) from cell phones, but the screens. So if someone pulls their phone out of their pocket even for a moment to check the time, the bright light draws my attention from the movie screen, even from quite a distance.

There is a variant of this that might be acceptable, which is that locations could designate themselves as “quiet” places, and when you enter them, your phone would require you to change it into silent mode or leave.

The location owner gets technological aid in rule enforcement. You get to decide if having your ringer on is more important than whatever you’re doing and go elsewhere.

Obviously, this would have to be supported/enforced by the phone OS. And there are downsides, so it’s not clear that it’s generally a good idea, but it’s better than not realizing that you can’t hear your phone any more.

It is both a thing and illegal. Three years ago, a guy was found to be actively jammed mobile phones on public transit trains here in Chicago. He was busted in a rare successful joint FCC-Chicago PD enforcement operation. He made it easy for them as his commuting schedule and route was apparently very predictable.

Even in places that almost everyone reasonable agrees jamming is a good idea, it isn’t allowed. The classic example is prisons. Phones are smuggled in and inmates use them for continuing their criminal enterprise. The staff unions are said to be responsible but the mobile carriers are the ones really pushing to continue the ban. They see it as a slippery slope. Once prisons, then hospitals, grade schools, places of worship and so forth.

I’ve played with some cheap jamming equipment. Nothing malicious, of course, but enough to convince me that it would be trivially easy to actively jam mobile devices over a pretty broad area.