Unity Connection call handlers for 911

Unanswered Question
Feb 16th, 2010

Environment is CUCM v7.1.3 with CUC v7.1.3. Multiple sites with 911 mgcp gateways (fxo) at smaller sites, PRI gateways at larger sites.

Having problems with misdialed 911 calls previously handled by introducing delay (inter-digit timeout) before routing calls. Wondering about configuring callhandlers in Unity Connections with greeting "You have dialed 911, stay on the line to be connected to emergency services" and then transfering the call to 911. The hurdle is how to route the calls coming from CUC to the correct gateway.

Any suggestions would be appreciated.

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Overall Rating: 4.5 (2 ratings)
William Bell Tue, 02/16/2010 - 07:44

I assume you don't have CER.  The approach you would need to take in this case is similar to how CUCM dial plan components are setup to support CER.  You would need a separate "911" pattern for each "area" or "emergency location".  This means you will need a separate Unity Call Handler for each area and possibly a few routing rules on your Unity system to make sure that the right "call handler" is hit when you place the 911 call from the station.

To support separate "911" patterns you will want to come up with some funky digit prefix like *91101 for area 1, *91102 for area 2, and so on.  Make sure you don't have overlap or conflicts, etc.   The *911xx pattern should point to the Route List that is appropriate for the site placing the 911 call.  You will need to manipulate digits for calling and called party so that the PSAP is happy with what you are sending them.

So, that is probably the way you would need to go.  It wouldn't be an incredibly scalable solution but you will have to make that judgement call yourself.  You also should work through fault scenarios like what happens when someone makes a 911 call and your Unity system is not available?  You can use Hunt Lists to handle this to a certain extent which means you would need a 911 Hunt Pilot for each tenant/area/emergency location on your system.  Then have the hunt pilot failover to a "last resort" 911 pattern (another unique digit pattern of some type) that will ensure the call goes to the correct PSAP.

My point is it is doable, just think through the scalability and fault tolerance aspects before putting it in place.

HTH. Please remember to use the rating system (for good and bad).


Tommer Catlin Tue, 02/16/2010 - 08:40

There a number of approaches you can use for this.  (all which are listed in NetPros search).   My only concern for you is the legal aspect of

this.  If the telephone system delays or does not connect 911 to a real call, is the company legally responsible....  which would be answered best by your legal eagles.  To me, routing 911 through Unity is a horrible solution.  Especially if Unity every goes down or is unavailable.

The prefix approach is correct if you are using CUC.   Or if you want, create a different 911 PT and CSS for each site, then translate it to a CTI that routes to Unity.

Id introduce a delay or interdigit time out to 5 seconds systemwide.   But there are other methods in NetPros if you search.  (some better ones)


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