On Sat, 6 Jul 2019 17:18:03 +0100, tony sayer
wrote:


Mobiles give location with varying degrees of accuracy. The basic
service sends the location of the mast being used via a simultaneous
Emergency SMS. This, in remote areas, can encompass a significant
area and in many rural locations is fairly useless. In urban areas
the basic information is quickly enhanced by mast triangulation as the
call is established. Advanced Mobile Location (AML), if available on
your phone operating system, uses GPS and WiFi location data to refine
location more precisely so works well in rural areas. (It works on
Android, not sure about others). Needless to say most emergency
services use different incompatible systems to handle calls. Some use
a data exchange system called EISEC ( Enhanced Information Service for
Emergency Calls) others voice.

Surely most all phones now use GPS and not triangulation ?...

Most certainly do but by no means all, really dumb phones are becoming
more popular. Also when relying upon any wireless device it is worth
remembering Marconi's first law of communication - "The ability to
communicate successfully using any wireless system is inversely
proportional to the need to do so"