One way Audi when dialing 911

Discussion in '3CX Phone System - General' started by GDavid, Aug 2, 2016.

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  1. GDavid

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    Howdy, haven't run into this one before, but maybe one of you has. We have several customers set up this way, but only one seems to be having an issue with 911 calls. And it's a fire station. Main difference with this customer is that they are in another city and have different PRI providers and various other telcos that could be between them and the party called.

    3CX 14, about 120 Yealink phones (T42 and T46 mostly)
    PRI with a Patton SN4970

    Everything works the way it should and we had no issues during initial installation and testing. However, recently its been reported at at least 2 stations that when they have to call 911, they get one way audio. The dispatcher can not hear them, but they can hear the dispatcher.

    When the Dispatch calls back, both parties can hear each other fine.

    I've put in a ticket with Patton to see if they have any ideas, and we're basically trying to narrow this down as much as possible. Googleing, I haven't found any specific Patton or 3CX issues like this. There was one forum post about Cisco systems that indicated that if the Gateway was a H.323 you need to run: voice rtp send-recv from the cli. I don't believe this applies to us, but perhaps something similar?

    We did some limited testing, and could not nail down with the 911 Dispatch what kind of equipment they were using or weather the call backs originated on the same equipment or phone system.

    Any ideas?

    thanks,
     
  2. leejor

    leejor Well-Known Member

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    Unless you are using the trunk group only for 911 calls, then there should not be any difference between that call any any other outgoing calls. That said, if the call has to traverse a number of "segments", then something could be ta play. There may also be an issue with a provider, and a route that the call uses. I would think that if all other outgoing calls are working correctly, then there shouldn't be a codec issue, but a check of the 3CX log, of a "silent call, might show something, if there is.

    You may need to narrow down the route that the "problem" call are taking.
     
  3. GDavid

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    Thanks for the response. We were thinking it might have something to do with that particular dispatch and the equipment they use.

    However, we have just cut over another customer and having a similar issue. Similar set up: Century Link PRI, Patton SN4970. All regular inbound and outbound calls have great 2 way audio. When we call 911, it just rings on our end and then gets cut off. On the Dispatch side, it rings and they pick up but get NO audio.

    Going to be sending the Patton's debug to support. Hopefully they will have an idea of where to go from here.

    thanks,
     
  4. leejor

    leejor Well-Known Member

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    If I had to guess (and that's really all it is at this point), it would be that the "(answer) supervision" on the 911 call is different, in such a way, that the PRI message back to the Patton is causing an issue. Perhaps century Link could monitor the messages on channel 24 to see what is sent for one of those calls as opposed to a "regular" call.
     
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