PSAP Operations

[rpneal44]

I have recently been hired at relatively large PSAP in the Mid TN area, and I am finding several components to which I have never been exposed before now. There's been a lot of discussion in the forums about how to get TO a PSAP and provide the proper originating-site information, but very little on how the components work once it gets here. In particular, the special 911 trunks and MFRs.

By no means am I a rookie, but one doesn't see these very often (1st time in my 25+ Nortel years) and I'd be interested in hearing from minds greater than mine on how these work.

Any takers?

Sincerely - Phildo

 

[Avaya911PLM]

Ok, here's how it works.

PSAPs connect to 911 Tandem Switches at the CO via CAMA trunks that use MF signaling. CAMA trunks send a special sequence of MF digits down the trunk to the CS 1000.

The CS 1000 takes this digit sequence which has the 7 or 10 digit ANI (aka Caller ID) embedded.

Here is where it varies:

PlantCML (the largest PSAP integrator with Nortel) connects their PC application to a 2216 telephone via the MCA adapter. Their VESTA application then 'reads' the ANI from the display. VESTA then does a data connection to the ALI/ANI database and queries or 'bid's for the ALI data (aka location information). The ALI is then presented to the call takers screen that got that specific call.

Positron PowerPC does it a different way. They use Nortel ACD agents and use the CDR generated on answer to query the agent position and ANI. They then use this to bid for ALI and display to the call taker.

Further information....
CAMA is usually configured similar to CENTREX from a functionality perspective, and when one PSAP needs to transfer to another, they actually issue a TFH (trunk Flash Hook) and then dial the ESN number of the other PSAP. The CO then effectively does a take back and transfer and re-terminates at the new PSAP, and the whole ANI/ALI sequence there is repeated.

A typical PS-ALI or ALI record for a PBX looks like this:

C1-66                   ESN=250             006
(972) 362-1745            07:18        10/13/08
2221          N          
LAKESIDE 
                         362-1745  PBX
RICHARDSON                         TX
BLDG 1   FL 10  LAB 7
NORTEL NETWORKS
ALT#=               TELCO=VzB
X=0.0000000000000
Y=0.0000000000000

RICHARDSON POLICE
RICHARDSON FIRE
RICHARDSON EMS

The X and Y coordinates are for cellular calls, and also these also carry a uncertainty factor giving the dispatcher a feel for how reliable those coordinates are (based on GPS, radio triangulation, etc.)

Hopes this gets you started. This is not the ONLY way to build a PSAP, for example you can add contact center in for 311/911 call capabilities with skill set routing like NYC does, or many other things.


--
Fletch

Nortel Emergency Services PLM

http://nortel.com/e911

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[rpneal44]

Fletch - Thanks for the response. I hope this has helped more than myself. Having viewed your contributions both here and on youtube, I was hoping you'd be one to jump on it. I'd be glad to see responses from others who might have something to add.

Anyone???

Phil, the Phriendly Phone Man