Subject: RE: [Ecrit] Timing of PSAPs changing coverage areas

From: "Tim Dunn" <[email-masked]>
Date: Fri, 23 Sep 2005 14:59:23 -0600

Nate-

My reference to circuit switched language was intended to answer the
question of whether or not “…anyone know(s) how often a location needs to
contact a different PSAP than its normal/standard one”.    I was in no way
defending the status quo of the circuit switched technology.  Realistically,
in many places in the US, call routing changes occur quite often and are not
“a statistical ‘outlier’" as was asked in James’ original statements.  I was
simply attempting to say that there we must take into account both time
based (the 8-5 PSAP) and situation based (PSAP Consolidation, Special
Events, Relocation to an Backup PSAP, Disasters, etc.) scenarios when we
talk about the routing of the emergency call to the PSAP.

I agree that we’re about to undergo a systematic review of PSAPs, responses,
and public safety communications in general as a part of the Katrina/Rita
events.  New funding streams bring the potential of new PSAP configurations
which makes the point even more that the PSAP call routing functions must be
flexible and able to have a call “…be served "on a moment's notice" by a
different PSAP”.

And not all PSAPs are consolidating, I know of at least one PSAP that
consolidated years ago and has re-split.

Tim Dunn

  _____  

From: Nate Wilcox [mailto:[email-masked]] 
Sent: Friday, September 23, 2005 2:08 PM
To: James M. Polk
Cc: Tim Dunn; [email-masked]
Subject: Re: [Ecrit] Timing of PSAPs changing coverage areas

Sorry I did not pick up on this thread sooner. As a former PSAP type person
I can tell you that in the State of Vermont over the last 7 years we have
had 5 significant PSAP reconfigurations that involved re-routing of calls to
new permanent locations. However, using historical references to determine
this is not going to help. Their is a shift afoot right now towards
dispatch/PSAP consolidation and the rate of change could increase
exponentially particularly as new funding mechanisms in pursuit of better
disaster preparedness becomes available for this specific purpose. I would
also add that bringing new PSAP's on line and decommisioing old ones will
become more common place as old cumbersome legacy gear gets replaced by more
capable, less complex systems.

Nate Wilcox

On 9/21/05, James M. Polk <[email-masked]> wrote:

Tim

This is a good example, and one that SIP covers already, as time-of-day
routing is a piece of cake to a SIP Proxy.

At 03:34 PM 9/20/2005 -0600, Tim Dunn wrote:
>James-
>
>In certain parts of the US (generally rural, but I think there are also
some 
>urban examples), I am aware of local police departments that answer their
>emergency calls between 8am and 5pm.  At other times the calls are routed
to
>a county or state level center that is a 24x7 operation.  So the answer to 
>your question would be that routing changes can occur daily in some places.
>
>
>In the legacy circuit switched environment, there is generally a way to
busy
>out the inbound emergency trunks, allowing for routing of calls to another 
>location.  In my example above, the local PSAP throws a switch and the
calls
>now route to an alternate location.
>
>This is also, in general, how trunk busyouts occur if a PSAP needs to
>quickly vacate and you want the calls routed elsewhere.  My experience was 
>that there were switches at the PSAP, at the central office (to busy out
the
>trunks) and sometimes at a local backup PSAP (unbusying those trunks to
>begin accepting calls).  If you had your primary and backup location out of

>business, there are switch level instructions on where to route.
>
>Tim Dunn
>
>-----Original Message-----
>From: [email-masked] [mailto: [email-masked]] On Behalf Of
>James M. Polk
>Sent: Tuesday, September 20, 2005 2:56 PM
>To: [email-masked]
>Subject: [Ecrit] Timing of PSAPs changing coverage areas 
>
>All
>
>I've heard and read the statements and requirements from folks that the
>routing of a call to a PSAP needs to be as fresh as possible because a
>particular PSAP might have moved, or more accurately, that a location might

>be served "on a moment's notice" by a different PSAP.
>
>I'd like to ask how often this happens today. Does anyone know how often a
>location needs to contact a different PSAP than its normal/standard one? 
>
>It seems to me that a lot of us might be imagining a worse-case scenario
>that we need to design protocols for, and that this worse-case scenario
>happens often. If this is, say only 0.01% of the time - or even under 5% of

>all emergency calls (2 standard deviations, or SDs), I'm thinking we're
>focusing too much energy on solving something that is a statistical
>"outlier".
>
>Today's emergency systems aren't build for 2 SDs, and especially not for 4 
>SDs.
>
>cheers,
>James
>
>                                  *******************
>                  Truth is not to be argued... it is to be presented.
>
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cheers,
James

                                 *******************
                 Truth is not to be argued... it is to be presented.

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