There is no point in asking people to be quiet. People who routinely yell on their cell phones in places they shouldn't are already boorish creeps who have no regard for the rights of others. What makes you think they'd listen to anyone?

I had to restrain The Boy from asking the Brazilian wax Bipsy if he could have a look. After all, the whole place had already heard the blow by blow account of her experience, so surely she shouldn't mind dropping her drawers so we could all see the result.

I married a smart aleck.

Granted, maybe if jammers were legalized and regulated we'd get better jammers, but from looking on the website http://www.phonejammer.com/, jammers operate from 800-1000Mhz and 1800-2000Mhz. This is BOTH the US and European bands (US: 850 Mhz & 1900 Mhz; European: 900Mhz & 1800Mhz). The big problem with this is that other organizations use frequencies in these areas. I'm pretty sure that public safety (IE, Fire, Police, etc) radios commonly use 800Mhz "Trunking" systems (pseudo cell systems that share frequencies).

So, by putting up one of these blockers, you are not only blocking cell phone use, but very possibly Fire & Police radio use.

Also, the jammers on http://www.phonejammer.com/ run from 500mW (portable) to 20 watts (largest base station). Modern digital phones max out at 600mW (0.6 watts) and police radios (portables, IE walkie-talkies) are usually 5 watts or so. So the largest jammer could easily interfere with police transmissions. (FYI, original car mounted or "Bag Phones" analog cell phones transmitted up to 3 watts.)

Here's a chart of US Frequency Allocation, but it doesn't go into great detail: <link>

Here's a list of US frequencies from a scanner web site: <link>

According to the Panix site, public safety uses 821-823 Mhz and 866-868 Mhz. Also, SMR (Specialized Mobile Radio - taxis, tow truck operators, etc) use 816-820 and 861-865.

Plus, "Personal Communications Services", that is, home cordless telephones, use 901 and 930 Mhz. So if your restaurant is near someone's home, you could be blocking 900Mhz cordless phones, or possibly other home wireless systems (baby monitors, security systems and maybe even those "Life Alert" necklaces). WiFi is 2.4 Ghz, so probably wouldn't be affected by one of these jammers (though it's possible that a more powerful jammer could bleed over into other frequencies, especially if not installed properly).

And, finally, Amateur radio ("Ham radio") has an allocation in the 902-928 Mhz range. A word of warning: if your jammer interferes with a amateur's use, they'll enjoy running around with a frequency meter to figure out what's going and and will possibly report you to the FCC. Amateurs (who are licensed by the FCC) take a dim view of people of people who use their frequencies illegally.

If you really wanted to jam a signal legally, you could just paint your theater/restaurant/etc. RF shielding paints do exist: <link> Probably wouldn't work with something that had windows, though.

BTW, want a completely random cell phone fact? An old tv that can receive channels 70-83 can receive analog cell phone signals! (Analog is pretty rare now, so you probably wouldn't hear anything if you tried, but you might.)

Aside from the remote possibility that a jury could be found somewhere in America that would actually convict him of sexual harrassment?:P

Wouldn't it be easier to just have special cellphone/no cell sections the same way many such businesses used to have smoking/no smoking sections (I'm assuming some states still allow them; my state isn't one of them.)?