It’s not a far fetched idea that some people just don’t like it when cell phones are used in certain environments. Many people find it a hassle to be without cell phone signal, but put yourself in the shoes of an art gallery owner on Opening Night with all his guests talking on cell phones while he delivers a speech. Or maybe you’re in a concert hall intently watching the King’s Singers perform their incredible rendition of Paul Drayton’s Masterpiece when a cell phone suddenly rings out of nowhere and surprises you half out of your wits. I’m sure that many people would find these examples acceptable uses for devices that can block cell phone signals and stop abusive individuals from using their cell phones where their usage isn’t appropriate. In fact, many such institutions do rely on cell phone jammers to prevent the frivolous usage of cell phones.

Cell phone jammers work by transmitting a signal on the same frequency as the signal being used by the cell phone service in a certain area and with enough power so that the two signals collide and cancel each other out. They are also designed to notice when cell phones in their vicinity try to increase their transmitting power in an attempt to cope with the low level interference, and match that increase with power with enough power to thwart any attempt at acquiring signal once again.

Since cell phone services rely on full-duplex transmissions, basically meaning that they use two separate frequencies for transmitting and receiving, some cell phone jammers will only block one of the frequencies, effectively tricking the cell phone into thinking that there is no service in the area because it is only receiving one of the frequencies.

However, some cell phones can also switch between different network types in case one of the network types is not working. These are called multi-mode phones and cell phone jammers also are built for them that block a whole group of frequencies or all commonly available cell phone frequencies.

Cell phone jammers come in a variety of shapes and sizes. For discreet uses, they can be made to look like cell phones or cigarette boxes, or any other item for that matter. They are also sometimes built into suitcases with their own power generating systems. They can also be very obvious, for use by a professional technician or in a professional installation where the presence of the cell phone jammer is advertised.

Because some cell phone jammers seem by their design to be intended for the use of ordinary consumers, it’s best to find out if their use without a license is legal in your country. Cell phone jamming is viewed as property theft in many countries, since providers actually pay to use the frequencies that are being blocked. The act of jamming cell phone signals can be seen as a safety hazard in its own right as well because it blocks all calls and texts, including calls made in emergency situations.

Nonetheless, some countries view disruptive cell phone use as an invasion to privacy and jamming is legalized for the purpose of preventing disruptive cell phone use. Countries such as France have legalized the use of cell phone jammers in theaters, concert halls, auditoriums, and other such performance venues. And some schools and universities in Italy use the technology to prevent students from cheating using their cell phones during exams. All-in-all, it’s always best to do some research and never use cell phone jammers for unethical purposes.

If it is legal for you to use a cell phone jammer, or are licensed to use one, you might find cell phone jammers in short supply in your area. In such cases, electronics wholesalers in China are your best bet, as the manufacture of jammers there is not as tightly regulated.