And there's a Santa Clause.
Many, and soon just about all, VOIP phones send across the Caller ID string associated with the account. The fact that (many) PSAPs can't use regular consumer CNID and do a comparison/sanity check against both the ANI string and the "911" caller info is due to their own equipment limitations.
(This is separate from the very real issue of the small number of folk who'd get a VOIP account in Lenexa, Ks, and then take the adapter with them and make calls that are physically coming from Uzbekistan)
Conveniently enough, the FCC maintains a list of PSAPs:
"Information regarding PSAP ID, PSAP Name, and PSAP County can be obtained from the FCC's Master PSAP Registry. The following state listings have been updated: Arizona, Arkansas, California, (etc., etc., and so forth)."So it would be trivial for the VOIP folk to do a translation of all calls placed to "911" and route them to the PSAP serving the registered "home" of the customer.
Now in regards to figuring out the exact boundaries, well, isn't it about time the local gov'ts got their acts together? In many parts of the country you'll find little or no coterminality between, oh, sanitation services, postal zip codes, water supply, fire protection, school districts, and police coverage. Now whose fault is that?
As a side note, wouldn't it be nice if the Feds got together and had a _central_, national, number for help? One that got a little office in, say, Cheyenne and had tie lines to every 911 PSAP?
Right now, for example, if I'm in East Cupcake, NY and on the phone with a friend of mine in Walla Walla and he collapses onto the floor, how am I supposed to get him help? Watcha wanna bet that if I called my local PSAP they wouldn't have a clue?
With a central office (at least available to the PSAPs, but really should be open to all) life would be much simpler.
_____________________________________________________ Knowledge may be power, but communications is the key firstname.lastname@example.org [to foil spammers, my address has been double rot-13 encoded]