Many Islamic terrorists have responded by declaring cell phones un-Islamic, and demanding that everyone get rid of theirs. The reasoning for this usually includes fears that the instant communication cell phones provide will lead to illicit relations between men and women. It's always about sex with these guys.
In Iraq, Islamic terrorists have been known to go around collecting cell phones when they move into a neighborhood. Often, the terrorists simply say its for security purposes, and that the phones will be returned when they leave. Here the reasoning is that a spy in the community will use a cell phone to call in an American smart bomb. It's always about suicide with these guys.
Terrorists have discussed using cell phone jammers, but this has not happened. Partly because the jammers are not that easy to get, and partly because the terrorists appear to have already figured out that the American's have sensors that can detect cell phone jammers, and send a smart bomb to where the jammer is. It's widely known in Iraq that the Americans did this to Saddam's GPS jammers during the 2003 invasion.
So the cell phone, which is seen as symbol of freedom to most people, is perceived as a tool of death by most terrorists. Cell phones are still used to trigger roadside bombs, but in the hands of unknown civilians, the cell phone is, to the terrorist, potentially fatal. Terrorists have not completely given up on cell phones, and still use them. But more carefully. Disposable, untraceable, cell phones are much desired. In some parts of the world, cell phones that fit this description are hard to acquire. Counter-terrorism forces have learned that constant attention must be paid to the illegal trafficking, and use of, cell phones. Terrorists, as a result, make use of criminal gangs that specialize in illegal (untraceable, or difficult to trace) cell phones. But, in the end, terrorists see cell phones as a very dangerous item.
Cell phones have turned out to be more of a curse than a blessing for terrorists. At first, terrorists believed cell phones gave them parity with the superior wireless communications used by the police and soldiers. Then, the terrorists discovered that cell phones could be tapped and traced. Oops, ditch the cell phone. But that wasn't enough. It seems that the civilian population, the terrorists operated among, also had cell phones. That was not good. Because some of those civilians did not like the terrorists, and were willing to let the police know what the terrorists were up to. Cell phones make it easier for police informants to make their reports. Texting is particularly popular, as it is silent. What is a terrorist to do?