In message , at 17:32:40 on Fri, 9 Aug 2019,
NY remarked:

I've heard conflicting stories about how much information about your
location is sent by a mobile phone when you make a 999 call: some
people say a full GPS reference is sent (assuming GPS is turned on at
the phone), some people say the phone estimates its position roughly
from knowing which masts it is near, and some people say that no info
is sent.

The phone doesn't estimate its cellsite position, it's done in the
network (which already needs to know roughly where you are for the
purposes of hand-offs between masts).

Of course, additional layers of location services software (like Google
mapping) can then send the answer back to the phone so they can display
it to the person holding it.
--
Roland Perry