Some calls (inbound and outbound) do not have audio (always one way)

Discussion in '3CX Phone System - General' started by John Ranger, Oct 18, 2017.

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  1. John Ranger

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    Hi all,

    lately I am observing that some of the calls (either inbound or Outbound) do not have Audio in one of the directions (it affects always only one of the two directions - sometimes I cannot hear the Person which is outside of our PBX (e.g. on PSTN) - in that case they can hear me ---- or they cannot hear me but I can hear them.

    If then the call gets hanged up (either by me or by them) and I or they redial then the Audio works again in both directions.

    The Problem always immediately goes away when redialed after a call where Audio has failed in one direction.

    Our 3CX Pbx Connects to the outside "phone world" via a Switzerland-Sipcall-based Voip Trunk.

    Hint: When we had V14, this Problem was not there but started after I migrated to V15.

    Any hints to how to start Troubleshooting this?

    Thanks and with Kind regards,

    John
     
  2. narkumas

    narkumas New Member

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    What kind of firewall do You have? Are You using SIP ALG?
     
  3. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    Hello @John Ranger

    Did you run the firewall checker of the PBX located on the dashboard of the management console? Were the tests successful?
     
  4. John Ranger

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    Hi Narkumas,
    we have a DrayTek VDSL router (Vigor 2850). So far this router has worked very well together with the 3CX System (using this combination already for several years).

    I remember that I turned off SIP ALG when I first installed the 3CX when we bought that router (3-4 years ago).

    But I have turned it off now again (don't know how to check on the router if it was already off or not).

    With Kind regards,

    John
     
    #4 John Ranger, Oct 18, 2017
    Last edited: Oct 18, 2017
  5. John Ranger

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    Hi YannisH,

    I am currently running it but this takes over 6h to complete as the test of each of the ports takes about 3/4 of a Minute --> Therefore I have suggested today under "new ideas" to parallelize this scan.

    I will Report what the Outcome is of this... Tomorrow...

    With Kind regards,

    John
     
  6. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    Please note that the test should not take that long. When i run it it takes ~2 minutes to complete the whole test. That would suggest that there is indeed an issue with your firewall.
     
  7. John Ranger

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    Hi Yannis,

    thanks for your Feedback. Good to know...

    With the FW tester in 3CX V12 this was much faster - but now this is slow. Nevertheless all 182 ports so far tested are done with a "green done" so it seems to basically work which means that the Basic FW config seems to be correct.

    The router/Firewall so far has worked great - also ist Speed is ok for us. The only Thing which takes Long over this Firewall seems to be the FW checker from 3CX :)

    I will "sniff" the traffic to the 3CX during such a FW checker test in order that I can see if there are some retries or so.

    Anything which you could add from your experience?

    Thanks and with Kind regards,

    John
     
  8. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    I would be a good idea running a capture side by side with the firewall checker to see what might be wrong. I would also check your machines resources in case there is an issue there. I h ave never seen a firewall checker test take this long
     
  9. John Ranger

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    Hi YannisH,
    the resources of the machine should not be the Problem: It is a VM running as the only VM on a recent quad core (8 thread) Xeon processor with 32 GB RAM on a Hyper-V-Server. The VM itself has 24GB RAM assigned.

    The physical CPU load on the machine is about 3-5%, inside the VM it is about 15-20%.

    The VM feels blazing fast when working via RDP on it.

    Did not yet managed to take a Network traffic capture and have to re-run the port check as we needed the phonesystem yesterday again.

    Will Keep you updated here what the FW checker has to say.

    John
     
  10. John Ranger

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    So: Made the full Firewall check run and all passed without any Problems altough it took a Long time.

    Interestingly since I did the SIP_ALG_OFF (again) and the Firewall checker run, no "one way audio" Problems have occured since.

    Either the force of the SIP_ALG_OFF or the restart of the 3CX Services (e.g. media_Service) has helped.

    I will observe this - and if it occurs again - then I will first restart the 3CX media Service.

    --> If this helps then I will schedule a periodic restart of the 3CX media Service once a day in the early morning.

    Thanks everybody for your help. I will post an update here if this occurs again and I implement some counter-measures.

    With Kind regards,

    John
     
  11. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    Hello John and thank you for the feedback. Please keep an eye on the issue and let us know if anything changes.
     
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