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One Way Audio - SIP ALG Disabled

Discussion in '3CX Phone System - General' started by David Catherall, Aug 25, 2017.

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  1. David Catherall

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    Hello again,

    Having problems with both incoming and outgoing calls from/to external numbers. One Way Audio, They can hear me but I can't hear them.
    Firewall check returns OK.
    Internal calls are fine.
    SIP ALG is disabled (I have tried 2 different routers)
    The router I am using is a Cyberoam Next Gen UTM device, but have tried using a cheap Zyxel too.

    On testing we can see that the call generated from port 9004 is going out as port 38000 (or thereabouts) so I assume the return path is trying the same port (38000). Is this where STUN is required?

    Strangely though, I have had two way audio working previously.

    any advice would be well received.

    Thanks,

    Dave
     
  2. AndreasPo_3CX

    AndreasPo_3CX Support Team
    Staff Member 3CX Support

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    Hi @David Catherall ,

    is the issue present with all incoming/outgoing external calls or does this happen only with a certain provider?
    you could try running a wireshark capture and checking if the audio comes back to the port you are sending it from (9004) or if the provider sends it to a different port.
    Another thing you could try for troubleshooting is creating free voip accounts and making calls between them to test if you get 2 way audio.
     
  3. David Catherall

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    Hi @AndreasPo_3CX ,
    All in/out calls. The audio isn't coming back to the port sent from, it's coming back as an entireley new port way out of the 9000-9500 range. I can see that the firewall is sending out from rule 0 (no other rules match=send from rule 0) though I do have the correct rules in place. I understand that NAT by its very nature changes the IP and port sent but I thought that's where STUN might come into effect.
     
  4. lneblett

    lneblett Well-Known Member

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    STUN is not the issue in this case as you indicate it is a port issue.

    Is this a new install or an existing and if existing, I assume it worked, so best to examine what may have changed in the meantime new cable modem perhaps. New firmware in router, etc.

    You might also take a look at:
    https://kb.cyberoam.com/default.asp?id=2234
    And try both on and off.
     
  5. AndreasPo_3CX

    AndreasPo_3CX Support Team
    Staff Member 3CX Support

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    @David Catherall ,

    could you send me the capture in a PM so i can examine it?
     
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