Vonage Selects TCS For VoIP E911 Service

Wed Jul 20 16:15:51 UTC 2005

Thus spake "Kuhtz, Christian" <christian.kuhtz at bellsouth.com>
>> On the other hand, maybe all you want to do is to route the
>> call to the right E911 center. In that case, as long as you
>> are in the right county you are probably OK.
>
> And if by chance you end up in the wrong county, as it happens
> from mobile phones on occasions, they will immediately transfer
> you to the right center.

At least around here, the PSAP folks answer with "<cityname> 911" and you 
can request a transfer to a nearby PSAP on the rare occasion they get it 
wrong.  Other areas in the country, however, don't have the ability to 
transfer; IIRC the SF Bay Area is a prime example of each PSAP not being 
linked to its neighbors (unless they've improved recently).

One enhancement I think is needed is a way to convey the level of confidence 
in the location information so the PSAP folks know if they need to verify it 
with the caller.  "Time since last updated" is probably a good input to 
that, but so are the historical frequency of change, the precision of the 
last fix, the method (GPS vs tower vs manual entry), and probably others. 
Another complication is what to do with people whose location changes 
(either due to movement or varying fixes) during the 911 call.

S

Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 