On Sun, 1 May 2005, David Lesher wrote:
Speaking on Deep Background, the Press Secretary whispered:
When somebody in the office picks up a phone and dials EXTERNAL-911 how do the emergancy services know they are in one building rather than another office across town?
The PBX intercepts the call and uses special trunks to the PSAP; it also has to send data telling where the caller is.
Here's one vendor: http://www.tonecommander.com/e911/How%20PBX%20ANI-LINK%20Works.htm
I think this scheme isn't going to work for VOIP. It relies on sending an ANI ID code which is setup in the E911 database with a more exact address. This is fine for a PBX with fixed phones. But it won't work for VOIP phones that could be anywhere now and somewhere else in 10 minutes, just by plugging them in to a new jack (and don't forget wifi phones). I think that VOIP phones will either ultimately be exempted, or required to have GPS (or triangulation or some other scheme), and the ability to send the GPS data to 911 services like cellphones. (And GPS doesn't work so well inside buildings, so I sort of doubt that its going to be very good as a locator for VOIP phones). I think that this is going to be a hard problem to solve. Or maybe we'll just start to see red phones next to the fire-alarm boxes. --Dean -- Av8 Internet Prepared to pay a premium for better service? www.av8.net faster, more reliable, better service 617 344 9000