I think this can work. Put a battery backup in the ATA, to power the GPS and real time clock. The ATA will maintain the internet-routable address it's using (not necessarily it's own IP address) indefinitely. If the ATA determines it's routable address (or /23 or whatever subnet) has changed since being disconnected, it prompts (via voice menu on connected phones) that it needs to be taken outside and re-GPS'ed. Flashing light on the box confirms when GPS has synced it's location. Take it back inside, plug it in, and all is ok again. Or something along those lines.... Chuck Church Lead Design Engineer CCIE #8776, MCNE, MCSE Netco Government Services - Design & Implementation Team 1210 N. Parker Rd. Greenville, SC 29609 Home office: 864-335-9473 Cell: 703-819-3495 cchurch@netcogov.com PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Michael.Dillon@btradianz.com Sent: Wednesday, July 20, 2005 5:32 AM To: nanog@merit.edu Subject: Re: Vonage Selects TCS For VoIP E911 Service

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I see no other way of doing this reliably than to put some kind of GPS device into the VoIP unit.

While I agree that GPS is the likely answer, I wasn't expecting the ability to work inside computer rooms and basements.

It doesn't need to work in basements, etc. It only needs to keep a record of the last location it was at when the signal faded away. The emergency service vehicles probably can't get any closer than that anyway. --Michael Dillon