From owner-nanog@merit.edu Sun May 1 17:41:59 2005 From: Chris Boyd <cboyd@gizmopartners.com> Subject: Re: FCC To Require 911 for VoIP Date: Sun, 1 May 2005 17:41:40 -0500 To: nanog@merit.edu
On May 1, 2005, at 11:53 AM, Christopher L. Morrow wrote:
so, how does this work when you dial into the internet in (or use your DSL) in newark and the termination point for L3 is in Philadelphia? That seems like more than 1sq mile...
In the dial up case, you could/should know the originating number, so location can be determined from that.
In rural areas, the 'precision' of *that* data is "highly variable". I know farmers who have 'private wire' strung from the house (where the PSTN terminates) to various outbuildings. In fact, I have an uncle who farms in S.W. Iowa, *right*on* the IA-MO border. The house is in Iowa, but he's got barns in the next county (which is also a different state!). It's all contiguous, so running the wire was no problem. (note: this wire went in _before_ cell-phones existed.)
In the DSL case, the ATM PVC can often be mapped back to a DSLAM port and thus a wire pair with a known termination.
Whether the provisioning and management systems are up to the task of providing this information quickly enough for emergency services, I don't know.
With DSL, you don't have to chase the wire-pair in 'near real-time'. The ATM PVC, or at worst the DSLAM port, uniquely identifies the customer. the customer records have the 'service address'. Even simpler, the source IP address, if static, directly identifies the customer, And, if dynamic, it just takes a dip into the authentication database to extract the customer ID. And pulling the customer record gets the service address. Of course, this is all *no*help*, when the customer has set up a wi-fi link with some "Pringles can antennas" (or better) and is actually several miles away from the DSL termination. The "correct" way to deal with the entire problem is to put a flag in the PSAP location database that says, _loudly_, on the E-911 console "This is a roving number. It does NOT have a fixed location. You must ASK THE CALLER where they are. 'Best guess', *but*only*a*guess*, on location is ..." The 'try to solve it with technology' approach would be for the SIP head- end to query the custeomer for his location any time it sees a _change_ of IP address for the customer equipment.