GPS doesn't work like that, it is receive only on the ground, devices don't transmit anything up to GPS satellites. Phones can only be located using cell towers or GPS info transmitted through a cell network.
A GPS handset is reciever only... The difference between a phone and a handset is that phones have access to wifi and 3g/4g where the recieved information is accessible by many apps, websites, and carriers monitoring all your data usage and locations. Considering the phones are "ringing," they have service and are surely within reach of towers to use that data.