from 21st Century Wire:
How do you know if a government of law enforcement agency has hacked your personal device? The truth of the matter is: most of the time you don’t.
One of the most common methods used by police to spy on the public, is by using an expensive piece of technology called a “Stingray,” manufactured by Harris Corporation in Florida. This special high-tech black box pretends to be a mobile phone/cell tower, allow police to divert your phone signal to their black box, rather than the nearly cellular tower. Moments after connecting their device to you phone, police can then gather a huge amount of information.