[Asterisk-Users] 911 Q

[Trevor G. Hammonds]

Joel Newkirk wrote on Friday, 30 September 2005 7:20 AM:

> Looking into setting up a couple asterisk servers at a country club,
> with VOIP phones in each of 100 short-term residential rental units. 
> Approx 100 extensions, approx 24 outside lines.
> 
> Since everything is geographically at one location, reaching 911
> correctly shouldn't present a problem.  However, the club wishes to
> ensure that 911 authorities are able to identify the precise rental
> unit placing the call.   

Mr. Newkirk,

This and similar situations present a very serious issue for emergency
responders.  When you dial 911, your call is routed to the appropriate PSAP
(Public Safety Answering Point) based on your ANI (Automatic Number
Identification) or ELIN (Emergency Line Identification Number -- usually
just another term for ANI).  As your call arrives, the PSAP does a query of
their ALI (Automatic Location Information) database to get your location
information.  Please note that the PSAP does NOT use Caller ID for this
purpose.  End users are not able to block their ANI (under normal
circumstances), even though they may block their Caller ID.    

Either the ILEC or a company like Intrado will maintain the ALI database in
your area.  If you are getting your PRI and DIDs from your local ILEC, they
would be responsible for getting the correct information entered into the
ALI database.  Typically, the information entered is only the physical
address where the primary service is installed.  In most circumstances, this
information is enough to get police/fire/EMS to you in an emergency.
However, I suspect the entire country club shares a single street address.
If so, when someone dials 911, the PSAP will get only the main address of
the country club.  In this and similar situations, such as calling from
within a multi-floor office building, a campus environment, etc., the main
street address is simply not enough information to get emergency responders
to you in a timely manner.  

Consider this not-so-unusual hypothetical scenario.  A guest of the
Pennsauken Country Club is having a heart attack in his bungalow.  He dials
911.  The dispatcher's screen at the PSAP shows the main information for the
club "(856) 662-4961 - 3800 Haddonfield Rd - Pennsauken Country Club -
Pennsauken, NJ".  The guest explains that he is experiencing severe chest
pain, then either passes out before he can tell the dispatcher his exact
location at the country club, or is confused or unaware of his exact
location.  The dispatcher would roll fire, EMS, and/or police to the main
address.  However, when they arrive, the emergency responders would have to
knock on all 100+ doors to even attempt to determine who was having the
emergency.  Now you probably have a dead guest.  Not good for business.  

First off, you should be using a PRI to connect your Asterisk server to the
PSTN.  You should also have a block of DIDs, with each guest room assigned
its own, unique DID.  This way you can differentiate among the individual
rooms when people are making outbound calls, and guests may receive incoming
calls in their room without going through an operator.  Asterisk is capable
of setting ANI in addition to Caller ID, on a per-call basis.  This would
ensure that the correct data is sent to the phone company when someone dials
911.  

As to getting the data to the PSAP to indicate where within the country club
each DID is assigned, you have a couple of solutions.  You can implement
PS/ALI (Private Switch/Automatic Location Identification), or you can work
with your telecom provider to have them enter the extended data into the ALI
database for each DID individually.  

PS/ALI is the "best" solution, from a technical standpoint -- but it is
usually quite expensive.  PS/ALI allows you to provide the E-911 system with
current, specific tenant location information to expedite emergency response
times to the site of the emergency -- not just to the building or general
site location.  So when your guest having a heard attack in room 119 dials
911, the PSAP gets something more along the line of "(856) 324-4119 - 3800
Haddonfield Rd - Building 5 Room 119 - Pennsauken Country Club - Pennsauken,
NJ".  

PS/ALI is geared toward larger telecom users such as colleges, office
buildings, large office campuses, etc., with a somewhat mobile population.
It is utilized best when most of your extensions or DIDs are assigned to a
person, as opposed to a location.  This way, when the person moves from one
office to another, your staff can push the change to the ALI database within
minutes of the move, rather than phoning in a service order to the LEC, and
waiting days for the change to be pushed to ALI.  

In your situation, I am assuming an extension or DID would most likely stay
at a fixed location for quite some time (e.g. extension 4119 is always going
to be guest room 119).  So PS/ALI may be overkill in your situation.  In
that case, I would go the second route mentioned above.  Work with your
telecom provider to get them to maintain the extended data in the ALI
database for each of your DIDs.  There may be a fee for them to do so, but I
am certain it is much less expense than the charges for PS/ALI.  Keep in
mind that any changes to the location data would require you to place a
service order.  

Let me know if you have any questions, or if I was unclear on an item.  

		Sincerely,
		Trevor Hammonds