New details of the Paris attacks carried out last November reveal that it was the consistent use of prepaid burner phones, not encryption, that helped keep the terrorists off the radar of the intelligence services.
As police pieced together the movements of the attackers, they found yet more burner phones: "Everywhere they went, the attackers left behind their throwaway phones, including in Bobigny, at a villa rented in the name of Ibrahim Abdeslam. When the brigade charged with sweeping the location arrived, it found two unused cellphones still inside their boxes." At another location used by one of the terrorists, the police found dozens of unused burner phones "still in their wrappers." http://goo.gl/32fuEa