Many phones manufactured after 2005 have GPS receivers built in. When the cellular phone detects that the user is placing an emergency call, it begins to transmit its location to a secure server, from which the PSAP can retrieve it. Cellphone manufacturers may program the phone to automatically enable GPS functionality (if disabled) when an emergency call is placed, so that it may transmit its location.
Phones go into an emergency mode where they transmit the gps location. The accuracy depends on factors including length of call iirc.
I believe they can then call the carrier to ping the phone to report location. Typically that happens if the dispatcher has reason to believe there is a emergency situation and the call drops.
I think the phone will notify you of this. At least it did many years ago when I called 911 for a car accident on the highway.
Could you elaborate? Get GPS how?