[Public Safety Answering Point]
While the only way to turn this tracking off is to shut down your phone, it is not actually activated unless you call 911. If you think this raises privacy concerns, just consider the nature of mobile phones, which are continually connecting to towers. Records are kept of every tower your phone communicates with. While it may not be as precise as true GPS, this information is being recorded any time your phone is on.
-from some website-