Since it captured Mosul in mid-2014 ISIL (Islamic State in Iraq and the Levant) has fought a losing battle to control information getting into the Iraqi city using radio, cell phones or the Internet. Soon after they drove the Iraqi security forces out of Mosul ISIL promptly seized the many AM and FM radio stations in the city and its suburbs and used them to broadcast ISIL approved information. Since music (live or recorded) was banned in all ISIL controlled territory keeping the Mosul radio stations running mainly served to jam radio stations outside the city from using the same frequencies. In addition ISIL brought in more and more jamming equipment that could go after transmitters outside the city using different frequencies.
The jamming program seemed to succeed at first this was ultimately futile because anti-ISIL Iraqis, especially the Kurds, had the technical skills and the motivation to overcome the ISIL jamming efforts. The Kurds were most successful with that because they had the best troops and could maintain troops closer to the city sooner that than anyone else. The Kurds used their close proximity for Kurdish and Arab Iraqis who were able to build and willing to operate FM radio stations close enough to the city to broadcast. These FM rigs were modified so that the operators could quickly switch to another one of several frequencies (known to listeners in Mosul) and avoid the jamming. Moreover these front line FM stations forced ISIL to install more powerful jammers because FM signals are stronger the closer the broadcast tower is to those tuning in.
ISIL tried to shut down these front line stations via more conventional means and that, so to speak, backfired. The Kurdish troops were able to take advantage of ISIL ground or artillery attacks by being prepared and accurately firing back. This made it very expensive (in terms of casualties and morale) for ISIL to come after these front line transmitters. This was mainly because the Kurds had another edge ISIL was familiar with. Since the early 1990s the Kurds in northern Iraq had access to American air support and aerial surveillance. While ISIL worships the past, they don’t seem to be learning much from it because the Kurds and their American air support took advantage of ISIL inflexibility in Syria (near the Turkish border) at the Kurdish town of Kobane in early 2015. The failure and heavy ISIL losses at Kobane hurt the ISIL reputation for invincibility but did not persuade ISIL leadership to avoid making the same mistake again outside Mosul when they tried to use brute force (masses of ISIL gunmen advancing on the objective) to shut down the troublesome radio stations.
By late 2015 ISIL had figured out that these tempting front line radio stations were basically a trap, to lure ISIL into making attacks they could not win. The failure to shut down this uncensored information encouraged resistance within the city. The radio stations could broadcast the kind of material Iraqis were accustomed to; news, talk shows and music. These stations also provided information on how to get around ISIL Internet and cell phone bans. This was crucial because by late 2015 there were more and more civilians inside Mosul who were willing to risk death (if caught) by sending out information about ISIL activities. This provided accurate target information for air attacks and plans for the offensive that will apparently take the city by the end of 2016. The continued operation of these anti-ISIL radio stations was also bad for ISIL morale because ISIL personnel could also listen to these broadcasts (even though it was forbidden and some ISIL men were executed after they were caught).
Undeterred ISIL continually escalated their efforts to shut down this electronic warfare effort. The problem was ISIL did not have sufficient manpower to do what needed to be done. For example in early 2015 ISIL banned the sale of radios in Mosul, but did not try to confiscate all the AM and FM radios already there, in homes, built into vehicles or battery powered portables. Some cell phones could also be used to listen to FM stations. For that reason ISIL then banned civilians from using cell phones. Again they did not try to confiscate the many (over 300,000) cell phones believed to be in the city. By September 2016 ISIL closed the last seven internet cafes in the city. These were the last places where civilians could legally use the Internet to communicate with areas outside ISIL held territory. After that any civilians caught using the Internet can be executed for espionage. That left the tempting but deadly front line FM radio stations. Many Mosul residents and a growing number of their ISIL oppressors saw this as a sign that the end was near.