[JdeBP]

If you want to learn more about this, then I suggest reading about the several and various initiatives that there have been over the past few years, in the U.K., the U.S.A., and elsewhere, to deal with with the problem of VOIP and mobile telephones. They have included things such as (for example) the idea that the immediately upstream ISP, for VOIP, populates an ESDB/ALIDB with location data that it knows because it knows the physical location of the VOIP connection to its network.

The names that you want to start with are "Enhanced 911" and "Next Generation 911".