phone fun, was GeoIP database issues and the real world consequences

Jonathan Smith beowulfdance at
Thu Apr 14 13:04:31 UTC 2016

"If they're land lines, the NPA/NXX will be local to the CO so you won't
have out-of-area numbers other than a rare corner case of a very expensive
foreign exchange line."

This hasn't been a true statement since Local Number Portability.  NPA/NXX
is nothing more than 'where the number originally was assigned from', and
that only for the ones issued BEFORE LNP started; since is anyone's guess.
They follow something similiar to what a routed phone call does, but ties
into slightly different information that is 'supposed' to associate the
end-client address with said LNI that is 'supposed' to be populated with
accurate street address information.  Similar to what VoIP has had to deal
with since, most charge a fee, disclaim any responsibility as to the
accuracy of the information that the end user provides.  I am sure
litigation on/around THAT particular issue is just around the corner.


Jonathan Smith
On Wed, Apr 13, 2016 at 11:22 PM, Jay Hennigan <jay at> wrote:

> On 4/13/16 8:54 PM, Peter Beckman wrote:
>> On Wed, 13 Apr 2016, Jay Hennigan wrote:
> When either of those people dial 9-1-1, where does the ambulance show up?
>>   I suspect your response was sarcastic, but when you dig into what really
>>   happens, it's not nearly as sophisticated as one might hope.
>>   If the numbers are land or VoIP lines, and the address associated with
>> the
>>   numbers are registered with the Automatic Location Information (ALI)
>>   database run by ILECs or 3rd parties to fetch the address keyed on the
>>   calling number, and the 911 PSAP is E911 capable, they operator will see
>>   the ALI address.
> If they're land lines, the NPA/NXX will be local to the CO so you won't
> have out-of-area numbers other than a rare corner case of a very expensive
> foreign exchange line. If they're VoIP lines, the address is *supposed* to
> be so registered, but softphones and even VoIP handsets tend to move around
> without the user considering 9-1-1.
> VoIP was the scenario to which I was referring. A VoIP phone native to
> 408-land that moves with a remote office worker to Boston without a
> conscious effort on his company and VoIP provider to track it down and
> update ALI will reach a PSAP in San Jose or thereabouts. The PSAPs have
> forwarding capability but generally only to neighboring PSAPs with a single
> button. How quickly will they be able to get the call routed to Boston, if
> at all? And as we saw at the beginning of the thread, forget geo-IP. The
> ambulance goes to the Vogelmans' farm. If a remote office worker, it could
> be VPN back to the VoIP PBX in 408-land anyway.
> So, it isn't just IP addresses that aren't easily geo-referenced. It's
> also phone numbers. The number may start as a well-referenced PRI going to
> an IP-PBX after which all bets are off. If the ANI is the company's HQ main
> number where the PRI and IP-PBX are located, then it's just about
> impossible to route 9-1-1 from a worker's IP phone in Boston to the right
>   If they are mobile devices, it depends. Basic gives you nothing (all
>> phones
>>   since 2003 should have GPS, but people hang on to phones a long time..);
> Mobile is a separate case where it's expected that the NPA-NXX isn't going
> to be tied to a location. In California, mobile 9-1-1 goes to the CHP and
> not the local PSAP based on the cell tower or GPS for that reason. If not a
> traffic incident, they forward to the appropriate PSAP based on the
> caller's info or perhaps whatever ALI (or estimate) they get from the
> cellular provider.
> --
> Jay Hennigan - CCIE #7880 - Network Engineering - jay at
> Impulse Internet Service  -
> Your local telephone and internet company - 805 884-6323 - WB6RDV

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