Cell Phone Bombs

Terrorists have long used cellular phones to trigger improvised explosive devices (IEDs) not only on Iraq roadsides, but also in attacks worldwide. Notably, cell phones detonated the bombs that destroyed public transportation in Madrid and London in 2004 and 2005 respectively; terrorists also planned to use them to bomb commercial U.S. flights in August 2006.

Although in the two previous cases, most of the bombs exploded within seconds of each other, one London bomb took nearly an hour to detonate after the initial attacks. This discrepancy has led some law enforcement advocates to conclude that police should be able to use cell phone signal jamming equipment to prevent future attacks.

However, under current federal law, only federal law enforcement agents can use such equipment. Local police fear this isn't enough; they cite, as one major issue, longer-than-desirable federal response times to terrorist incidents or suspected plots. As a result, one vendor has challenged the law.

How terrorists use cell phones

"The remote-control IED is terrorists' first choice of bomb today," says Howard Melamed, chief executive officer of Coral Springs, Florida-based Cell Antenna Corp. "That's because they're so easy to construct and deploy." Bombers use the cell phone as a typical remote control: to send a signal via radio airwaves. The signal energizes a relay connected to a blasting cap, which in turn detonates explosive material.

Although remote controlled toys and keyless entry devices set off bombs too, cell phones remain the most popular. That's because they're convenient in a variety of ways:

  • Using 1200mA x 3.7-12 volts, they have just the right power.
  • They have time synchronization capabilities.
  • They have an extremely accurate alarm clock function.
  • They include a vibration circuit that can be addressed by phone number or function.
  • They allow for worldwide usage.
  • It's impossible to track where they come from and where they go — especially if they're disposable.
  • It's easy to get inside their circuitry.
  • They're easy to conceal.
  • Their highly unstable batteries are easily ignited.

Of these features, two are of crucial importance: the phone's vibration function, and the battery.

The vibration function is the part terrorists use to trigger bombs. "The mechanism consists of a motor with an asymmetrical wheel," Melamed explains. "That's what shakes the phone. A terrorist using it as a trigger simply removes the motor and connects the circuit to the relay or blasting cap." At that point, the terrorist can use the phone's alarm or a simple phone call to trigger the vibration circuit — and thus the bomb. Melamed says terrorists who want to see the explosion often dial the phone.

The cell phone's battery is also critical. "Most cell phones use lithium ion cobalt batteries," Melamed says. "This material is highly unstable. In fact, manufacturers include warnings that the batteries may explode if tampered with or exposed to fire." When a battery shorts, he continues, one of three things happens:

  1. Nothing.
  2. An explosion.
  3. A flame-up, or fire.

Batteries are designed to "fail safe," as Jim Akridge, CEO of Austin, Texas-based Valence Technologies Inc., explains. "Electronic circuits control the rate of energy discharge. Inside the cell casing are two safety devices. One limits the current, and the other limits the pressure build-up. These batteries are designed to shut themselves off if they're shorted externally." Additionally, he says, all batteries are built with strong, hard-to-open cases.

However, Melamed says some illicit batteries made overseas lack these fail-safes. In 2004, manufacturers such as Verizon Wireless and Kyocera Wireless issued recalls for the counterfeit batteries they had unknowingly used in their cell phones. Sony and Nokia now issue documents that warn consumers to use their proprietary batteries for this reason. Terrorists may use "bad" batteries in their bombs — or adapt "good" batteries by overriding their safety circuits.

Either way, lithium ion cobalt batteries' easy availability and chemical instability make them attractive to terrorists who want to use them for "battery bombs." (Melamed notes that because laptops use the same battery material, terrorists may choose to use the larger laptop battery as the main explosive, and the smaller cell phone battery in place of a blasting cap.)

Valence is focusing on large format batteries, replacing lead acid and nickel metal hydride with its Saphion I technology. The company is not currently focusing on consumer electronic devices for its Saphion I chemistry. Akridge says: "Lithium ion batteries that use cobalt-based cathodes are still the best choice for portable electronic devices because of their light weight and storage capacity for their small size. Phosphate-based cathodes have better safety characteristics than those containing cobalt. Temperatures that cause phosphate cells to catch on fire cannot be generated by the phosphate chemistry. Phosphate cells, having lower energy density than cobalt cathodes, make them less attractive for consumer devices."

How jamming equipment stops IEDs

Although Melamed could not discuss specifics, a jamming device blocks the cellular downlink frequencies, preventing a cell phone's ability to receive an incoming call. (Uplink capabilities still function.)

Jamming equipment only stops some of a cell phone's functions from working. It cannot prevent a cell phone's alarm function — effectively, a timing device — from detonating a bomb. Melamed estimates it can impede half of all cell phone bombs, along with remotely controlled bombs that use other tools, such as garage door openers or toys. Separate equipment exists to prevent bombs that use the alarm function. "Terrorists use the simplest materials they can find to make bombs," Melamed notes. In other cases, it's possible to control cell towers' signal; some phones turn themselves off if they can't find a signal. In others, a bomb technician may "mate" with the phone to set the timer back.

Melamed says jamming equipment is very location-specific, meaning cell phone traffic in an entire urban area could not be jammed. "We compare it to a police officer stopping vehicular traffic: only that particular street is stopped, and only in one direction," he explains. "Our equipment can jam as much as necessary, but only for a specific period of time and only in a certain building or subway station. Officers can also select the frequencies they jam. For instance, they could jam downlinks for everyone's phone except emergency services.' " During a period of heightened alert, police might choose constant jamming for areas like close-to-the-surface subway stations. The goal, Melamed says, is to avoid the pandemonium terrorists want to elicit.

Does law enforcement need jamming equipment?

"FEMA [and its response to Hurricane Katrina] showed us that federal agents are not the first line of response to catastrophic incidents," says Melamed. While cell carriers can shut down towers in an emergency — in much the same way the airline industry grounded all flights on 9/11 — an emergency protocol to do so only recently became available, and falls under federal purview.

Melamed says these issues are complicated by the possibility that cell carriers may extend signals into commercial airspace. "Phone signals don't interfere with navigation; no plane ever came down because someone forgot to turn their cell phone off," he says. That the need for constant communication outweighs public safety is already an issue in Washington, D.C., where carriers provide underground signals for subway commuters.

A bomb squad could use a jamming device to prevent a primary explosive from detonating; or, following a primary attack, prevent additional bombs from going off. However, Melamed says agencies that have contacted his company have many more uses in mind. Hostage negotiators could jam all signals except the single line they need; narcotics officers could jam signals on a street where a bust was about to take place, severing spotters' ties to dealers. Patrol officers could jam signals on vehicles they pursue or stop, guaranteeing that they could get — and keep — subjects' attention. And correctional facilities could jam downlinks to jails and prisons, preventing inmates from "doing business" with their gangs or other associates on the outside.

Why law enforcement lacks jamming equipment

According to the Federal Communications Commission (FCC)'s Web site, "The operation of transmitters designed to jam or block wireless communications is a violation of the Communications Act of 1934, as amended ('Act').

  • [47 USC Sections 301, 302a, 333] The Act prohibits any person from willfully or maliciously interfering with the radio communications of any station licensed or authorized under the Act or operated by the U.S. government.
  • [47 USC Section 333] The manufacture, importation, sale or offer for sale, including advertising, of devices designed to block or jam wireless transmissions is prohibited.
  • [47 USC Section 302a(b)] Parties in violation of these provisions may be subject to the penalties set out in 47 USC Sections 501-510. Fines for a first offense can range as high as $11,000 for each violation or imprisonment for up to one year, and the device used also may be seized and forfeited to the U.S. government."

Cell Antenna Corp. has challenged the Federal Communications Act in the U.S. District Court for the Southern District of Florida. Melamed argues that the Act conflicts with the 14th Amendment's due process and equal protection clauses, in that the Homeland Security Act (HSA) of 2002 implicitly repealed the Federal Communications Act. Language in the complaint reads, "Whereas the FCC prohibits the sale of RF and cellular jammers to state or local police departments, the HSA consistently and repeatedly directs the Department of Homeland Security to take whatever measures are necessary to empower local law enforcement agencies and first responders in the fight against global terrorism." In particular, Section 701 of the HSA reads that the government must "coordinat[e] with state and local government personnel, agencies, and authorities, and with the private sector, to ensure adequate planning, equipment, training and exercise activities ..."

The FCC has filed a motion of dismissal for the case — for technicalities, Melamed notes, not merit — and Cell Antenna Corp. remains the only entity involved. Cell Antenna has countered in court, saying that this issue is of utmost importance and cannot simply be set aside. Other organizations, including the International Association of Chiefs of Police (IACP), have chosen not to file supportive briefs. Although the IACP has not taken an official position on the issue, according to spokesperson Wendy Balazik, other organizations have — on both sides.

Kevin Barry, a U.S. spokes-person for the International Association of Bomb Technicians and Investigators, says his organization supports any measure — including local police use of jamming equipment — that would make bomb squad operators safer on the job. "The amount of time the equipment would be in use is minimal," he notes. Agreeing with Melamed that federal response may, depending on many factors, lag significantly behind local response, Barry says local police need a way to further secure the perimeter around a site — and to help control public panic, which would likely result as teams waited for a federal responder with the jamming equipment.

On the flip side, Joe Farren, spokesperson for the Cellular Telecommunications & Internet (The Wireless) Association (CTIA), says his organization supports the ban on local law enforcement access to jamming equipment. "Movie theaters wanted the technology as a way of cutting down on public nuisances, but it would interfere with legitimate emergency communications — someone trying to reach a surgeon, parent or first responder," he says.

Acknowledging that, whether via jamming equipment or an agreement with carriers, law enforcement may need part of a network shut down — and that precedent exists to do this — Farren says the CTIA is at work with the DHS to develop just such a protocol. However, he argues, DHS should have sole authority as to its implementation. "Federal agents are in the business of assessing terrorist risks and threats, so they should be in charge of the protocol for interfering with cellular communications," he explains. "There are significant risks to shutting down a network, including the fact that emergency personnel trying to control a threat will lose part of their ability to communicate."

A statement released by the National Communications System (NCS) expands further on the protocol. "The Department of Homeland Security — through the department's NCS — has coordinated with state officials on a voluntary plan for cellular service disruption in the event of a specific threat," the statement reads. "The recommendation has been approved following review by the Department of Homeland Security and was sent through the Department's State and Local Government Office to State Homeland Security Advisors for implementation. Details of the plan are not releasable for reasons of national security." The statement goes on to say that members of the President's National Security Telecommunications Advisory Committee addressed cellular service disruption via a series of recommendations for shutdown. These include a specific process to be followed after an order has been issued for disrupting cellular service.

In the future, Barry believes that the need to keep up with terrorist adaptations of cellular technology will push federal agencies to supply local agencies with jamming and other electronic countermeasures. "They might dispense it to attendees of hazardous device schools and training, or to agencies whose bomb technicians are on a list of certified personnel," he says. In other words, training everyone according to federal protocol will allow local agencies to retain some control over the equipment's use, but still meet their needs.

"The cause outweighs the risk to business," Melamed says. "Under the Federal Communications Act, a bomb has more rights than the people it will kill. Times have changed; the Act doesn't address national security." The bottom line, he says, is that law enforcement must be ahead of terrorists if they are to prevent and mitigate attacks effectively. "Everyone looks stupid, and are quick to say 'if only we had known' when people die — even though it could easily have been prevented with a jamming device."