Fake Cell Phone Towers Tracking Phones

...Once it has made a connection with the phone and tricked it into thinking it is a mobile tower, the IMSI catcher forces the phone to drop its encryption, enabling easy access to the contents of the device. The tool then lets the attacker listen in on mobile conversations and intercept all data sent from a mobile phone, remaining undetected. In some cases the tool also allows the operator to manipulate messages. Here.  Also