North American Network Operators Group

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Re: Vonage Selects TCS For VoIP E911 Service

  • From: Stephen Sprunk
  • Date: Wed Jul 20 12:50:35 2005

Thus spake "Kuhtz, Christian" <[email protected]>
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