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Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your

Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your mobile to look up anything while in-store? I know a few places I shop where my cell coverage "mysteriously" drops to nil inside the store and I have long suspected it's not just the concrete walls.

Ajedi32 9y ago
That'd be illegal, so I kinda doubt it. Not to mention that jammers are pretty easy to detect with the right equipment so it'd be fairly easy to prove if they were doing something like that.
callalex 9y ago
The FCC comes down HARD on anybody doing that. https://www.fcc.gov/document/marriott-pay-600k-resolve-wifi-blocking-investigation https://www.fcc.gov/document/marriott-pay-600k-resolve-wifi-...
RIMR 9y ago
If you suspect cell jamming, and you're in the USA, contact the FCC and report the business. The mere fact that it interferes with 911 is enough to send a store manager to prison. If they can prove that an emergency vehicle every got close enough to the business to be potentially affected, the business could see hundreds of thousands of dollars in fines. The FCC could just park a van in front of the store for 3 minutes and their tools would verify that a jammer was in use. Here's the details on anti-jamming laws, and a list of people who have had their ass handed to them by the FCC for doing it: https://www.fcc.gov/general/jammer-enforcement https://www.fcc.gov/general/jammer-enforcement
- sixdimensional 9y ago
  Good to know this. I don't think it's outright cell jamming but something where voice service is still passable but data service basically cannot function due to packet loss, etc. Would be interesting to try to detect if such interference is present on the right frequencies, or if it is just a natural effect and truly not intentional. Thanks for sharing the info.
  - prostoalex 9y ago
    > something where voice service is still passable but data service basically cannot function due to packet loss, etc. That pretty much describes 99% of indoor mobile coverage out there. The only exception being buildings that have ponied up for a femtocell.
dragonwriter 9y ago
> Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your mobile to look up anything while in-store? Actual jammers? Unlikely because it's highly illegal, quite detectable, and will cost more than anyone could hope to gain by it. Deliberate, passive measures that practically impede indoor reception may happen, though.
- Consultant32452 9y ago
  >Deliberate, passive measures that practically impede indoor reception may happen, though. It does seem that some buildings are suspiciously effective Faraday cages while others are not.
  - sixdimensional 9y ago
    Yes, this is exactly the effect I am talking about. You go into the store, and effectively, using the cell network for data goes to zero, but the cell voice service still works. Could it be something that makes the cell network jittery or adds latency that interferes with cellular data but not voice service?

Ajedi32 9y ago

That'd be illegal, so I kinda doubt it. Not to mention that jammers are pretty easy to detect with the right equipment so it'd be fairly easy to prove if they were doing something like that.

callalex 9y ago

The FCC comes down HARD on anybody doing that. https://www.fcc.gov/document/marriott-pay-600k-resolve-wifi-blocking-investigation https://www.fcc.gov/document/marriott-pay-600k-resolve-wifi-...

RIMR 9y ago

If you suspect cell jamming, and you're in the USA, contact the FCC and report the business. The mere fact that it interferes with 911 is enough to send a store manager to prison. If they can prove that an emergency vehicle every got close enough to the business to be potentially affected, the business could see hundreds of thousands of dollars in fines. The FCC could just park a van in front of the store for 3 minutes and their tools would verify that a jammer was in use. Here's the details on anti-jamming laws, and a list of people who have had their ass handed to them by the FCC for doing it: https://www.fcc.gov/general/jammer-enforcement https://www.fcc.gov/general/jammer-enforcement

sixdimensional 9y ago
Good to know this. I don't think it's outright cell jamming but something where voice service is still passable but data service basically cannot function due to packet loss, etc. Would be interesting to try to detect if such interference is present on the right frequencies, or if it is just a natural effect and truly not intentional. Thanks for sharing the info.
- prostoalex 9y ago
  > something where voice service is still passable but data service basically cannot function due to packet loss, etc. That pretty much describes 99% of indoor mobile coverage out there. The only exception being buildings that have ponied up for a femtocell.

dragonwriter 9y ago

> Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your mobile to look up anything while in-store? Actual jammers? Unlikely because it's highly illegal, quite detectable, and will cost more than anyone could hope to gain by it. Deliberate, passive measures that practically impede indoor reception may happen, though.

Consultant32452 9y ago
>Deliberate, passive measures that practically impede indoor reception may happen, though. It does seem that some buildings are suspiciously effective Faraday cages while others are not.
- sixdimensional 9y ago
  Yes, this is exactly the effect I am talking about. You go into the store, and effectively, using the cell network for data goes to zero, but the cell voice service still works. Could it be something that makes the cell network jittery or adds latency that interferes with cellular data but not voice service?