Wi-Fi blockers and jammers are a notable topic in news reports about burglars in 2024, but is your smart home security in jeopardy?

Wi-Fi blocking sounds dangerous, but it's unlikely to be a threat to your home

One of the big selling points of smart home security is that it can make your home safer and more convenient. But you may have seen reports in 2024 about burglars using new technology to block Wi-Fi signals, jamming valuable camera systems or video doorbell connections and rendering them useless. This news report discusses police warnings about break-ins using Wi-Fi jammers in Los Angeles and Glendale, and here's a scary-sounding story about jammer burglars hitting homes in Minneapolis.

If you're worried, you're like many other homeowners who worry that their devices -- especially Wi-Fi cameras and sensors -- won't alert them in the presence of mobile Wi-Fi blockers, catch the thief, or even call a monitoring station for help.

Wi-Fi jammers do exist, but they are unlikely to pose a threat to your home or any of your devices.

Let’s summarize your reasons to stay calm:

• The above reports are general messages from police to their communities, with little evidence of Wi-Fi jammers being used and only wealthy neighborhoods being robbed. In some cases, local reports explicitly state that police are only saying thieves “might” have used jammers, not that they’ve caught anyone in the act of committing robberies. Some burglar arrests, like this one in Connecticut in 2023, do provide evidence of jammer devices, but this is one of the very few that has been confirmed.
• Smart home encryption helps prevent such attacks and can notify owners of problems immediately.
• Burglars may not have the time or resources to buy and learn new technology. They’ll smash your windows or drill your door latches—blocking Wi-Fi isn’t their plan.
• More likely, a suspected smart home security malfunction is the result of a dead wireless device battery or a failure of motion detection to activate due to a motion zone or detection sensitivity issue.
• According to a 2019 FBI report, burglaries account for only 16% of property crimes, with only about 60% of those involving residential thefts and only about half of burglaries involving any kind of forced entry. It’s also worth noting that between 2010 and 2020, burglaries overall dropped by about 50%.

However, Wi-Fi jamming technology does exist, and despite FCC laws prohibiting the sale of such technology, thieves can still find and purchase jammers online.

NBC10 Investigators tracked down a cell phone sniffer who specifically targeted people using their cell phones on SEPTA bus routes. Not only did he admit to doing it, he thought it was a good thing.

The man, who calls himself Jonathan, told NBC10 Investigators, "I guess I'm taking the law personally, and frankly, I'm proud of it."

Jonathan said he doesn't want to hear people talking on their phones in public.

"It's still pretty annoying, and frankly, it's pretty rude," Jonathan said. Jonathan

said he was activating a cell phone jammer he bought online to block out conversations he doesn't want to hear.

"A lot of people are very loud and have no sense of privacy at all. When they feel like they're bothering me, I just screw in the antenna and turn the switch on," Jonathan said.

An NBC10 employee, whom NBC10 Investigators calls "Brooklyn," said she was horrified when she saw the man jamming passengers' cell phones while she was riding a SEPTA bus to work.

"He was clearly holding this device that looked like a walkie-talkie, with four thick antennas on it. I started watching him, and whenever someone started calling, he would press a button on the side of the device," Brooklyn said.

Brooklyn tipped off NBC10 Investigators, who went undercover and caught the phone thief with hidden cameras.

Minutes after boarding the No. 44 bus, NBC10 Investigators spotted Eric jamming a cell phone. Weeks later, they caught Eric as he got off the bus and told him cell phone jamming devices were illegal.

"From what I understand, it's more of a gray area. From what I understand, it's illegal to stop TV signals, radio signals. From what I understand, it's not illegal to jam cell phone signals under the FCC," Jonathan said.

But under federal law, it's illegal to use, possess, buy or sell a cell phone jammer. The federal government says violating the law could result in jail time and a fine of up to $16,000. Cell phone jammers are illegal for public safety reasons.

Dr. Rob D'Ovidio of Drexel University studies cell phone forensics and e-crime. D'Ovidio said some cell phone jammers can block GPS, two-way radios and even police radios if they are close enough.

"With a cell phone jammer, you can limit all types of communication tools that use radio frequencies. That has the potential to be a public safety disaster. It's a dangerous thing to cut off not only our government officials from communicating with the dispatch center, but also the public from communicating with 911," Dr. D'Ovidio said.

NBC10 Investigators asked Jonathan if he was worried about disturbing someone who was seeking emergency help.

"Certainly, if that happened on a bus, I think I would have been in that situation. Of course, I think that would have been a very different situation; I think I would have called 911 myself," Jonathan said.

SEPTA officials said they have received many complaints from 44 bus route passengers about lost phones. But SEPTA insisted that passengers are safe, adding that they have tested their system and handheld signal jammer alone are not enough.

SEPTA said all buses are equipped with panic buttons. Drivers can also alert police via digital destination signs on the front of buses. The transit authority said it has tested two-way radio communications and insisted cellphone jammers wouldn't affect it. But that didn't make Brooklyn feel any better.

Karyn Wall has lived in Lemon Grove for the past 20 years, and to her knowledge, her home has never been targeted by criminals. However, she recently learned how vulnerable her home is to would-be burglars.

“My husband and I feel very secure, but I know we may need to do something about the house, the interior, the lighting, etc.,” Wall said.

Shanah Clevenger is a crime prevention specialist with the San Diego County Sheriff’s Department who runs the free Lemon Grove Home Security Consultation Program. She’ll consider anything that can be done to bolster home security, no matter the budget.

“Some of my suggestions are quick and easy and don’t cost a lot,” Clevenger said. “I just suggest: do what you can, or do it incrementally until you feel your home is secure.”

That security measure includes protection against a relatively unknown type of wifi jammer. NBC 7 Responds spoke to cybersecurity expert Jim Stickley about these devices, who said that even though they are illegal in the U.S., there are several websites where you can buy them and have them delivered to your door.

"I mean, you shouldn't panic," Stickley said. "It's real, but the number of criminals who actually use it is relatively small."

How do Wi-Fi jammers work?

Jammers disable Wi-Fi devices by overloading the Wi-Fi frequency, or any radio frequency, and large jammers have a fairly wide range of interference, Stickley said.

"It could take out a whole house, or even a couple of houses around me, and take out all the Wi-Fi," Stickley said.

Once the Wi-Fi is down, criminals can break in without the cameras capturing it.

How to disable a WiFi jammer?

Wired cameras won't be affected by signal jammer, of course. Remember: The memory chip will record video whether or not there's Wi-Fi. Plus, some security systems offer systems that send owners notifications when Wi-Fi is down.

"If you get a notification that the Wi-Fi can't communicate with the camera, you can say, 'OK, something might be wrong,' and then you can call a neighbor and say, 'Hey, can you go check it out for me?'" Stickley said.

Wall said she couldn’t imagine coming home one day to find her home ransacked by strangers.

“That would be horrible,” Wall said. “That would be horrible because you’d be worried if there was someone else in the house and wouldn’t want to go in. That would be a very scary situation.”

Wall hopes to continue living safely in Lemon Grove for another 20 years.

The sheriff’s department said technology is important to keep your family and home safe, but it’s just as important that you and your neighbors look out for each other. They can also help start a neighborhood watch program.

The National Telecommunications and Information Administration (NTIA) has released a report detailing the results of its micro-jamming technology test conducted on January 17, 2018, at Cumberland Federal Correctional Institution in Maryland.

Test data showed that the micro-jamming signal interfered with commercial wireless signals inside the cells, meaning that if cell phones were used inside the cells, they would not work. However, at 20 feet and 100 feet outside the cells, the micro-jammer signal did not interfere with commercial wireless signals.

Department officers present during the January 17, 2018 test reported that while their cell phone signals were blocked inside the cells, their phones still worked when they stood a few feet from the cell windows.

"These encouraging test results mark a step forward in our efforts to combat the security threat posed by contraband cell phones," said Beth Williams, Assistant Attorney General for the Justice Department's Office of Legal Policy. "The results show that this micro-jamming technology has the potential to have a localized impact. This is an encouraging sign that we are closer to solutions that make our communities safer and help prevent the continuation of criminal activity within prisons."

The data in the report will be used by the BOP and the Department to understand the effectiveness of micro-jamming, further evaluate jamming technology, and develop strategic planning recommendations.

Contraband cell phones continue to be a correctional security and public safety concern for the Bureau of Prisons and state and local correctional institutions. Across the country, inmates use contraband cell phones to direct gang activity, operate criminal enterprises, distribute child pornography, intimidate witnesses, and facilitate the commission of violent crimes. "This test is just one part of our ongoing efforts to disrupt and disable dangerous contraband cell phones in federal and state prisons," said Assistant Attorney General Williams.

The Bureau of Prisons will continue to evaluate cell phone detection and blocking technologies and work with federal partners and Congress to find cost-effective options to combat this threat to prisons and public safety. The agency does not endorse any specific vendor or product.

Carr Pushes for Federal Legislation to Combat Contraband Cell Phones in Prisons

ATLANTA, Ga. – Attorney General Chris Carr and 21 other attorneys general are urging congressional leaders to pass legislation that would allow states to implement cell phone jammer systems in correctional institutions. Currently, federal law prohibits the use of jamming technology, including jamming cell phones. Meanwhile, prisons across the country are using contraband cell phones with no way to stop them.

“Cell phones in the hands of criminals are an ongoing safety concern, not only for Georgia, but for correctional institutions across the country,” said GDC Commissioner Tyrone Oliver. “We appreciate Attorney General Carr’s support in finding a solution to this problem, which is critical to our commitment to public safety.”

As of January 1, 2023, the GDC has conducted 126 full facility searches and seized more than 23,000 contraband items. Last year alone, 8,074 contraband cell phones were seized.

In a letter sent on January 25, 2023, the Attorney General outlined the national challenges associated with contraband cell phones.

The letter reads: “The use of contraband cell phones by inmates is one of the most serious issues facing prison administrators today. Inmates use contraband cell phones to organize murders, riots, drug trafficking, fraud, etc. By using contraband cell phones, inmates can easily continue their criminal activities inside prison.”

Previously, Congress has introduced several bills to address this issue, including H.R. 1954 in the 116th Congress and H.R. 864 and S. 4699 in the 117th Congress. However, these bills have not made any progress and have never received a vote.

To jam a 5G signal, an intelligent adversary can detect unencrypted synchronization signals to obtain the physical cell identity (PCI) and then launch a targeted cell phone jamming attack on the physical broadcast channel (PBCH). This intelligent jamming (PBCH-IJ) disrupts the master information block (MIB) decoding, leading to denial of services for users trying to access the PCI cell. The proposed method in the paper suggests detecting PBCH-IJ by analyzing the principal direction of PBCH demodulation reference signal space at the user side, as this direction is significantly impacted by PBCH-IJ under low mobility scenarios.

Jamming attacks on 5G signals can be executed by exploiting various vulnerabilities inherent in the 5G network architecture. One common method involves targeting the synchronization signal blocks (SSBs) during the initial access phase, as these blocks are unencrypted. An intelligent adversary can detect these signals to obtain the full physical cell identity (PCI) by sniffing, and then use the PCI to attack the physical broadcast channel (PBCH) extraction through targeted jamming. This type of PBCH intelligent jamming (PBCH-IJ) disrupts the decoding of the master information block (MIB), leading to severe denial of service for users attempting to access the PCI cell. Another approach involves using a multi-antenna jammer to interfere with the downlink signals from femto base stations (FBS) to femto users (FUs) in a two-tier 5G heterogeneous network (HetNet). This can be particularly effective in dynamic environments where traditional anti-jamming techniques like frequency hopping (FH) and direct sequence spread spectrum (DSSS) lack self-adaptive capabilities. To counteract such jamming, advanced techniques like federated deep reinforcement learning (DRL) have been proposed, which optimize beamforming and power allocation to improve the achievable rate at FUs despite the presence of signal jammer. Additionally, jamming detection in 5G can be enhanced by using the "EVM-vs-RB" measurement, which calculates the Error Vector Magnitude (EVM) for each Resource Block (RB). This method is more sensitive and informative, capable of detecting jamming even at high Signal-to-Jamming Ratio (SJR) values, which traditional metrics fail to identify. These methods highlight the sophisticated techniques adversaries can use to jam 5G signals and the equally advanced countermeasures required to mitigate such attacks.

I was there in an exhibition yesterday. Most of the times, i was not able to use my cellphone data internet. But, i was able to make calls with the phone most of the times. Now, i have a doubt here. I happened to call a friend who was also to the same show, and he did say that he was not able to access the cellphone internet there. He said that they had used Network Jammers, though he was not certain about it.

My question here are:

• 1) Can network jammers only restrict data and not calls? How is it possible??
• 2) Will there be separate jammers for 2G/3G/4G/5G, based on it's spectrum?
• 3) Are jammers free of health hazards?
• 4) What could be better designs to use than jammers?

1. network jammers can selectively block data services while allowing voice services. This is possible because voice and data services use different network protocols and frequencies. A network jammer can be designed to block specific frequencies and protocols while allowing others to pass through.
2. there are different types of cell phone signal jammer for 2G/3G/4G/5G networks since they operate on different frequencies. Each technology operates in a different frequency band and therefore requires a specific jamming device.
3. Network jammers emit high levels of electromagnetic radiation that can be harmful to humans if they are exposed to it for extended periods of time. The radiation emitted by a jammer can cause cancer, DNA damage, and other health problems. Therefore, network jammers are not free of health hazards.
4. There are alternative methods to restrict network access in specific areas without using network jammers. For example, using Faraday cages can block all electromagnetic signals from entering or leaving an enclosed space. (There is graphite paint for example for walls, normally it is connected to ground with metal strips under the paint.) Another approach is to use signal blockers that selectively block specific signals without affecting other services. However, the effectiveness of these alternatives is limited, or they would just be too expensive, and jammers remain the most effective way to block specific network services in a specific area.

The possible misuse of internet can be one reason to block data services. Also, the method were used, i'm not sure now, when a person decorating high post in the country uses public transport infrastructure.

The possible reason would be high capacity which the BTS (for that particular cell) wouldn't be able to provide. This point needs to be valid, since the network used to fall back to lower generation at times. Again, i'm not sure how the BTS would automatically cut off the channel width based on the number of connections.

As said above, in order to prioritize the audio calls, the frequencies used will get the connectivity to 2G or 3G.

NBC News reports that online retailers and drone technology companies are marketing RF jammers as drone deterrents or privacy tools, thereby circumventing laws that prohibit the sale of such devices in the United States.

The warning issued by the Federal Communications Commission (FCC) states that signal jamming devices can block emergency calls and pose a serious risk to public safety communications, while also interfering with other forms of everyday communications and air navigation systems.

The FCC said: "It is a violation of federal law to use phone blocker, GPS blockers, or other signal jamming devices designed to intentionally block, disrupt, or interfere with authorized radio communications. Use in businesses, classrooms, residences, or vehicles is not exempt. Local law enforcement agencies do not have independent authority to use jamming devices; federal law enforcement agencies may use them under applicable regulations under certain limited exceptions."

The FCC warning also states that "it is illegal to advertise, sell, distribute, import, or otherwise market jamming devices to consumers in the United States"

But NBC reports that Amazon third-party sellers, independent online stores based in China, and small domestic companies that specialize in drone-related equipment are all ignoring the law. The FCC told NBC that it is investigating the sale of jammers, including on Amazon.

As part of its investigation, NBC spoke with the CEO of a U.S. company that offers portable anti-drone radio frequency jamming devices online. The CEO told NBC that the devices are easily available if consumers have the money, but they mainly see interest from large companies and government agencies as they prepare for domestic drone terrorism.

There are more people selling "jammers." The devices can block cell phone calls, text messages, Wi-Fi networks and GPS systems and can be used to cause chaos in public places.

The small, battery-powered devices can be used to create "blind spots" in a small area (usually around 30 feet) and have been used by movie theaters, restaurants and schools to prevent people from using their phones. But they can also cut off 911 calls, interfere with navigation near airports, and have been used to disrupt radio communications near police stations. FCC officials said they have noticed an increase in the flow of jammers, which are banned by federal law, into the United States. Many of the cheaper versions, which sell for as little as $25, are imported from Asia, according to the agency.

It is illegal to sell, advertise, use or import jammers under the Communications Act of 1934, which prohibits blocking radio communications in public

The FCC said cities including Orlando, Philadelphia, Austin, Mississippi, Charlotte, North Carolina, Washington, D.C., Cincinnati and Corpus Christi, Texas, advertised jammers on the site. Officials said they do not believe the cases are related.

"Simply posting an ad for a signal jammer on a site like Craigslist.org is a violation of federal law. Signal jammers are contraband for a reason," Michele Ellison, director of the FCC's enforcement bureau, said in a statement. "One person's moment of peace or privacy could very well jeopardize the safety and well-being of others."

Most sellers advertised jammers as a way to take an "undisturbed nap" on a bus, quiet a classroom or keep your area "free of interference," without mentioning the more nefarious uses the device could be used for, according to the citations.

"We are increasingly concerned that individual consumers operating jammers do not appear to understand the serious consequences of using jammers," one citation reads. "Instead, these operators mistakenly believe that their illegal operations are personal convenience or should be excused."

Keith Grabowski allegedly advertised on Philadelphia Craigslist for a "cell phone jammer, WiFi signal jammer" for $300. He stated in the ad that "due to the nature of this item, we are disclosing very few details," that the jammer was "not a toy," and that "I just want to get rid of it as quickly as possible."

As things stand, technology is eating into the fun of being a teenager, and Ford's MyKey and this device can ensure you're actually safe while driving. Seriously, the poorly named Key2SafeDriving is a great idea (at least in the eyes of parents), as it incorporates a cell phone jammer (sort of) into a key fob to block calls on the highway. Essentially, as soon as the "key" portion is popped out, the signal jammer activates, connecting to the phone via Bluetooth or RFID and forcing it into "driving mode." No jamming actually occurs; it's more like manually controlling the ringer. Anyone who calls/texts you while you're safely driving will receive an automated response informing them of the situation, though we're told a hands-free device is available. The University of Utah researchers hope to bring it to market through a private company within six months, "at a cost of less than $50 per key, plus a yet-to-be-determined monthly service fee."

TxTStopper Announces In-Car Cell Phone Signal Jammer

Texting while driving is a very dangerous blood sport. Knowing that still won't change the behavior of a disrespectful teenager. So, parents, why not take matters into your own hands and install a mini cell phone jammer in your car at home? TxtStopper is a professionally installed 12-volt device that apparently shuts off all communications from all U.S. cell phones in the car when the car is started and in gear -- yes, that includes non-driving passengers. Unfortunately, TxtStopper's website chooses to play on consumer fears rather than provide any real technical details, so we'll just have to trust them that it will work as advertised, okay? For $200, maybe not.

The problem is so bad that yet another state -- Georgia -- has joined 27 other states, the District of Columbia, and Guam in enacting laws that prohibit teen drivers from using cell phones while driving. Georgia's new law, which goes into effect July 1, 2010, is the latest in a nationwide effort to create "no cell phone zones" recently initiated by media mogul and mega-philanthropist Oprah Winfrey.

TxTStopper™ has taken the ‘No Phone Zone’ a step further with the launch of a patent-pending accident avoidance technology that turns any vehicle into a ‘No Phone Zone’. A spokesperson for TxTStopper™ said: “Personal commitments and national campaigns to stop texting, calling and emailing while driving are laudable; but the reality is that we are so ‘addicted’ to communication and constant multitasking that unless our phone is left at home, it will be used while driving.”

Two weeks ago, the Morris County Police Department made headlines when it warned of an attempted burglary using a Wi-Fi signal blockers But just how concerning is the technology? Experts interviewed by NorthJersey.com have different opinions.

In a notice to the community, Police Chief Joseph Orlando said that around 11:30 a.m. on June 10, a Florham Park resident in the basement of his Lincoln Avenue home reported hearing noises coming from the first floor.

The resident briefly saw an unknown man on his security camera trying to enter his home, but both the camera system and his cell phone lost signal. Orlando said police later determined the suspect used a Wi-Fi jammers, which disabled all Wi-Fi-accessible devices in the house.

Orlando called the method used in the burglary an "astounding advancement in technology" and a level of sophistication the area had never experienced before.

"While Wi-Fi jammers are nothing new to criminals, this is the first time we've seen or heard of them being used in Morris County," he said.

The Morris County Sheriff's Office declined to comment further on the alleged crime or the increase in such activity, saying it was an active investigation and commenting could adversely affect the outcome.

But criminals are becoming "more and more sophisticated," according to Tom Shea, former director of Seton Hall University's graduate program in policing and a retired Long Beach police officer. He said this level of activity is "getting worse and worse" because technology is readily available and affordable to the average person.

He likened it to a game of cat and mouse

"Criminals are getting more sophisticated, and law enforcement has to figure out what they're doing and get better tools," Shea said, "and then criminals figure that out and they get different tools."

Brian Higgins, a former Bergen County police chief and professor at John Jay College of Criminal Justice in Manhattan, believes such criminal activity is still relatively rare and largely avoidable with proper precautions.

Higgins said he doesn’t see this type of break-in as a trend yet, noting, “It’s pretty high-tech; you have to know what you’re doing.” However, he added, “I think you’ll see more of it” as tech-savvy criminals figure out how to defeat security systems.

Now, security companies must get ahead of the curve and keep their customers safe.

Higgins and Shea believe that after the first jamming incidents became public, system operators began looking for solutions and eventually rolled out new features to combat the practice.

This type of crime has become more common as companies like Ring and SimpliSafe have introduced wireless alarm systems. These systems are designed to make it easier for homeowners by connecting all devices to a single source, but that also means they’re easier for criminals to dismantle.

“If you can jam Wi-Fi, your alarm system is disabled,” Higgins said, comparing the practice to another recent exploit of new technology: stealing parked cars from driveways where owners leave their keys inside.

Wi-Fi jammers, which are illegal under federal law, can also block signals from police intercoms. Earlier this year, Democratic Rep. Carol Murph of Mount Laurel introduced a bill that would criminalize Wi-Fi jammers at the state level. The bill was referred to the Assembly Judiciary Committee in February.

In the Florham Park incident, the resident stopped a pedestrian on the street, who called 911. Officers from the Florham Park and Madison police departments and the Morris County Sheriff's Office responded to the scene but were unable to find the suspect, who fled after realizing the resident was home.

First it was cars, now it's homes in a 'sleepy suburb'

Shea said the gangs started out just selling drugs or stealing cars in affluent neighborhoods, but over time the criminals have become more sophisticated, learning new techniques and constantly trying to stay one step ahead of police. The risk is worth it, he said.

Florham Park police linked the alleged theft to an overseas criminal group. Shea said that's not surprising because transnational crime "is nothing new." He said the pace of globalization is accelerating every year, thanks to technological advances, and that crime is becoming easier to commit.

So how can police departments keep up?

Law enforcement throughout northern New Jersey has likely already met to form a task force to combat the growing “complex crime,” but if not, Shea said it’s critical that police “wake up” and realize they need to address the crime because he’s seeing it “get worse and worse.”

And it’s likely that this crime will continue to infiltrate the suburbs.

Some criminals are very smart and have had plenty of time to train for what they do, Shea said. With the new tools, they realize that surveillance homes in quiet, upscale suburbs are easy targets because police aren’t necessarily as vigilant as they would be in the city center.

Searching on Google's shopping site showed dozens of links to devices that are advertised as signal jammers, including anti-drone devices. Google itself does not sell them, but instead directs shoppers to third-party sellers, such as electronics retailers in China. These retailers typically say they can ship to the United States, and their marketing materials are not specifically for military or law enforcement use. One Chinese seller posted a video on YouTube, which is owned by Google, demonstrating how its product blocks cell phone signals.

A Google spokesperson said the company has reviewed the cases shared by NBC News and is removing listings that violate its policy prohibiting the sale or promotion of such devices.

Sometimes it's unclear who is behind the online sellers. One retailer called itself "Professional Global Signal Jammer Manufacturer Online Jammer Store" but did not disclose its location. The company did not respond to a request for comment. The FAQ section of its website includes the following dialogue:

"Will customs confiscate my package?"

"So far, we have not encountered this situation."

It is unclear how many people may have illegally purchased radio frequency drone jammers from the various websites reviewed by NBC News. At least some of the companies said they sell their products to customers outside the United States, where the FCC's strict rules don't apply.

At the other end of the radio signal jammer market are military suppliers, government contractors and other companies that don't generally target their products at consumers. Many of these companies have websites marketing their products, but they don't list prices or offer options to buy them immediately. Instead, they list options to "request a consultation" or "contact an expert."

An FCC spokesman pointed to the commission's standing advisory on law enforcement and a 2020 federal interagency advisory on drone defense.

On Wednesday, after NBC News published the report, the FCC said it had received several investigations related to jammer marketing, including one involving Amazon.

"We are conducting several investigations into retailers, including Amazon, for possible violations of the commission's rules by marketing and selling devices without proper FCC authorization," FCC spokesman Jonathan Uriarte said in a statement.

Amazon did not immediately respond to a request for comment on the investigations on Wednesday.

The FCC has cracked down on radio frequency jammers and their online sales. In 2016, the commission said it had fined a Chinese online retailer, CTS Technology, $34.9 million for selling hundreds of illegal jammers over two years and selling some to undercover FCC agents.

There have been no similar fines in the U.S. since then, though other Chinese retailers still market radio jammers to Americans online, an NBC News review of their websites shows. NBC News could not determine if any of them have shipped products to the U.S.

The FCC has also targeted buyers in past years. In 2018, the FCC said it fined the operator of a Dallas warehouse $22,000 for using a jammer to prevent employees from using their cell phones while working. In 2016, the commission said it fined a Florida man $48,000 for using a jamming device to prevent people in other vehicles from talking on their cell phones during his daily commute. In 2014, Marriott agreed to pay $600,000 to settle allegations that one of its properties in Nashville, Tennessee, interfered with Wi-Fi signals at non-Marriott hotels.

Over the years, the FCC’s focus has shifted to other topics, such as combating robocalls, said Dale Hatfield, a former chief engineer at the commission.

“Their enforcement activity seems to be more targeted at things that are more directly visible to consumers,” he said.

It’s hard to determine how big a problem illegal jammers are because signal interference is often brief and hard to document, said Hatfield, an adjunct professor at the University of Colorado Boulder. For the same reason, he said, interference cases are difficult for the FCC to handle.

“It can be very intermittent,” he said. “How do you go back and figure out why?”

Former FCC Commissioner McDowell said the commission’s enforcement efforts are largely determined by the types of complaints it receives.

“Typically, the enforcement process comes into play when an outside agency notifies the FCC of a situation,” he said.

Jamming devices have many potential uses, from disrupting unwanted drones to disrupting Wi-Fi networks to disabling doorbell cameras. On a Reddit message board dedicated to Ring doorbell cameras, some posters complained about people using jammers to disrupt the cameras and avoid detection during thefts. One Reddit poster said the irony was that Amazon seemed to be profiting from both sides: Ring is a division of Amazon, and Amazon is also a marketplace for buying devices that can disable Ring cameras.

Amazon did not respond to questions about jamming Ring devices.

Jammers, or radio frequency "blocking," are also a frequent topic of discussion in online forums dedicated to people who believe that the government or others are conducting deep surveillance on them, a belief or phenomenon sometimes referred to as "gang stalking."

Potential markets for anti-drone systems such as RF jammers include large businesses and organizations that are concerned about drone terrorism but are not legally allowed to use jammers. Last year, four major sports leagues, including the NFL, urged Congress in a letter to congressional leaders to allow state and local law enforcement to use anti-drone capabilities.

Prison officials in some states have said they want legal authority to use jammers to prevent prisoners from using their phones.

But under current law, the list of government agencies authorized to buy and use radio frequency jammers is short, including the FBI and the Department of Homeland Security, as well as the Departments of Energy and Defense.

Companies that specialize in drone countermeasures often focus on foreign buyers.

Drone defense company IXI Electronic Warfare warns on its website that drones pose a potential threat to stadiums, prisons and airports, and says drones can help "eliminate threats in seconds," including using a radio frequency jammer called a "Dronekiller." But overall, stadium operators, prisons and airport authorities do not have the legal authority to buy such products in the U.S.