In article , Robert Bonomi wrote:[[.. munch ..]]
It still exists today. Either as actual hard-wire to the remote CO (with a *BIG* one-time install charge, plus a moderate monthly) or, more commonly, as a 'virtualized' service.
Funny thing about FX lines, the telco _does_ know where the end of that line is. In your scenario, if you called 911 on that line, while the call _might_ go to the PSAP for locale where the switch is, the*location* *information* given to the police would be accurate.
The accurate POTS parallel to the VoIP 'location' problems is the situation where there the telephone company service terminates at a PBX, and there are 'extensions' *BEHIND* the PBX to 'remote' locations. The *telco* _does_not_ _know_ anything about what goes on behind the PBX, and can only report where =their= service terminates. Which leads to the telco providing "wrong answers" to the 911 center.
Cell phone systems have the same problem. The point at which a cell-phone call is connected to the PSTN is _not_ necessarily anywhere "close" to the tower which is handling the call. AND, that tower may be in a different 'jurisdiction' than the one where the person _placing_ the call is.
A review of actual 911 history will show that *both* of the above scenarios were real problems in the early days of 'enhanced 911'. In the first case, governmental regulations were issued that require PBX owners to keep the PSAP 'location database' updated with the*actual*location* of all extensions that are behind that PBX.
The cell-phone problem was considerably thornier -- and went through a number of steps:1) cell phone links were *blocked* from calling 911 because "wrong data" was being displayed. 2) 911 calling was re-enabled when it became possible to return "no data" for those calls, instead of "wrong data" as to the location. 3) enhanced technology was mandated/deployed _on_the_cell_ network (*NOT* a part of the PSTN) that allowed fairly precise _caller_ location determination 'on the fly'. 4) Where that technology was deployed, "good" (as in valid/accurate) 'location' data was then passed to the PSAP, instead of the prior "no data".
Dealing with VoIP involves much 'harder' problems than either of the above. To have the phone itself figure out "where it is" it has to have straight-line inputs from a minimum of two sources that it (a) knows where are, *and* (b) can take directional bearings on, OR a minimum of three sources that it can measure signal timing from. AND it has to be able to reliably derive that information at _any_ location where the phone might be used.
Using GPS is not a viable option -- 'indoor' reception is too poor. And the 300 ft accuracy is problematic. That last can be remedied by using DGPS, but that makes for a more expensive receiver. And doesn't do anything for the fundamental reception problems. The only solution for _that_ problem is to replace the transmitters with more powerful ones. Which is *awfully* expensive.
LORAN-C might be a possibility, it carries indoors fairly well. BUT, it operates at 100kHz, which requires a non-trivial antenna for decent reception. *AND* it is only accurate to around 1/4 of a mile. "within several blocks" is simply not good enough for emergency-service dispatch.
One is left with the possibility of direction-finding on local commercial stations. This could possibly be made to work, but requires access to a fairly massive database of *precise* transmitter locations. The equipment required to get a precision bearing on a transmitter isn't cheap, either. (If you're 10 miles from the transmitter, a _one_degree_ uncertainty in direction makes for +/- nearly a thousand feet in your location.)
"Technology" is not the solution for this, "Policy" is. The two-part solution described previously does get the job done. Administratively, not via technology. All the burden (what burden there is) is on the VoIP provider and the actual 'owner' of the phone. And it probably takes 30 days, or _less_, to get it into 'production' status at any/every major VoIP provider.
I stand "corrected". PAT _has_ come up with the ultimate solution. With his proposed 'local ISP'-based handling of emergency calls,*NOBODY* but the person who set up the VoIP service -- and knows where it connects through -- is allowed to use the phone in an emergency. "So what" if that person is unconscious on the floor from a heart attack, and the VoIP phone is the only one available, and someone who _doesn't_know_ that it is an IP phone, or where it connects through, cannot call for help.
No need to even consider the situation of the person who takes "their" phone to a friends place, because they may have to make some lengthy toll calls, and simply _don't_know_ where _that_ broadband service is out of. After all, that could _never_ happen, could it?[TELECOM Digest Editor's Note: No, of course it _could_ happen, but what are the odds? Figure the 'odds' based on these things: the VOIP phone is on the road somewhere, not in its usual place. The subscriber has an incident and needs help. Not only does _he_ not know where he is at (or is not in a position to speak to the police) and the _phone_ does not know where it is at. There is no landline available, and/or the person in trouble not only cannot get to the (landline) phone, or whatever. My personal reaction is _all those factors taken in combin- ation_ are so negligible as to not matter at all. As soon as any one of those conditions does not exist, the problem is dealt with. We do not live in the town of 'Perfect' as the commercial for Walgreens states. And you know what, Robert? Even if magically, every one of those rare obstacles were overcome tonight, magically, _YOU_ would come up with still more obstacles, wouldn't you? And after all, why not? You swear on a stack of tech reference manuals that _nothing_ can be done to tame the 'wild west' lifestyle of the internet. I have never yet seen you ever admit to any possible cure for the nastiness on the internet. It just has to be the way it is, because Robert has all the (non) answers. Why shouldn't any problems with E-911 and VOIP turn out the same way. You don't really want to see any answers to any of those problems, do you? And rather than do _something_ and bring some small amount of relief to the vast majority of users, there will still be some iota-percentage we are unable to help, given our understandings. So better to do nothing at all, right Robert? I thought your thinking was absolutely ludicrous where spam/scam/viri was concerned, but people have seen nothing at all until you explain the 'hassles' (as you see them) with 911 and VOIP. PAT]