In article <firstname.lastname@example.org>, Robert Bonomi
[[.. munch ..]]
> The "easy" solution is a two-part one.
> Part 1: The VoIP 'head end' tracks the 'most recently used' IP
> address for each customer. _EVERY_TIME_ the customer IP
> address changes, the phone goes *out*of*service* with a
> notice that the customer must update their "calling
> Possibly with an added hook that if the phone has been 'off
> line' for some non-trivial period, that when it goes back
> 'on line', the customer is queried (in an automated
> fashion) to confirm that they are still at "thus and such
> location"; where "thus and such" is the previously
> specified location for the phone.
> Part 2: The VoIP 'head end' maps the various 'calling locations' to the
> appropriate PSAP, upon need.
> Add an option for the customer to intentionally _not_ specify his
> location, but which also totally disables 911 calling. This protects
> his 'privacy' at the expense of his safety, but it is the customer's
> The last part of the puzzle is ensuring that the customer is aware
> that the "location information" provided is used for "emergency calls"
> and that deliberately providing FALSE information can (and probably
> _will_) lead to criminal prosecution if emergency services are
> directed to an incorrect location as a result of said false
> information. There is already existing enforcement mechanism for this
> -- "filing a false police report", etc.
[[.. munch ..]]
> Now, silly as it sounds, something that "works right" 98% of the time,
> but "invisibly" does the _wrong_ thing the other 2% of the time is
> *worse* that something that 'almost never' gets it right.
> An essential element of a 911 'locator' system it that it either gives
> a 'right answer', or it gives *NO* answer. "Wrong answers" are simply
> not acceptable -- wrong answers (a) delay the response to the location
> where it is needed, *and* (b) tie up resources that may be needed to
> respond to a 'real' emergency.
> [TELECOM Digest Editor's Note: Well ... regards your first point, of
> a 'tunnel' to some remote place, do you remember when 'Foreign Exchange
> Service' (or FX) was quite common?
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.
> So, one day in my office, a masked man breaks in, and waving his
> gun around, he announces, "I am going to rob all the cashiers and
> rape all the men". I say, 'oh no you are not!' and rush to my phone
> to call the police. But in my haste I grab up the FX tie-line phone
> and dial '911' -- (or as Bonomi would say, ooops) ... -- and wind
> up lodging my complaint with the politce in Kalamazoo and Timbuck also.
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
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
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.
> If a _real man_ does not know where his broadband service is out of,
> then he has no business calling the police to start with, does he? PAT]
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]