poor sound quality, cracking

Discussion in 'General' started by areid, Aug 21, 2008.

  1. areid

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    For incoming routes, we are using voip. The sound quality is poor and it is cracking. Outgoing calls for are cracking once in a while. Our zap (landlines) are working good.

    Our card for zap is Openvox A400P21( 4 port analog PCI card + 2 FXS + 1 FXO ).

    Has anyone solved this problem?
     
  2. rafael

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    Hi areid ,

    Let me see if I understund how you are working. You have sip trounking to recieve calls and zap to make calls. The problem is in the incoming with de sip trunks. This might be an issue of what codec you are using. If you are using g729 for example you should have something like this on the trunk configuration:

    disallow=all
    allow=g729

    Regards,

    Rafael
     
  3. MageMinds

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    What kind of Internet connection do you have aDSL, Cable, Fiber Optic, WiFi etc... What is the bandwidth available? Do you have a QoS router? Is the cracking happening when you also download at the same time? What codec do you use? Keep in mind that to use g729, you have to install it manually. How many VoIP Voice Path do you have? Post a traceroute to your sip provider server when the problem happen to see where the problem might be ... You should have ping time below the 100ms.

    MageMinds
     
  4. areid

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    1/ aDSL
    2/ .6 Mb up, 6.0 Mbs down
    3/ yes for QOS router, setup is 500 Kbit/sec upstream, 3000 Kbits/sec downstream
    3/ we are using g711, should we use g729? where do download manually?
    4/ voip voice path - not many
    5/ ping and it was below 100ms
     
  5. MageMinds

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    Humm your problem doesn't seem to be network related. TO make sure you could test your SIP account directly into an ATA to see if you have similar problems, if not, then the problem is Asterisk, what is the computer specifications?

    As for the g711, each communication in g711 uses around 10 KB/s in both direction, it's in fact 64 kbps for the codec which translate to 8 KB/s plus the IP packets headers, so with the kind of Internet connection you have you can barely handle 5 VoIP calls at the same times and if you do forget about downloading and uploading on the Internet... With g729 you could handle easily twice and maybe triple that amount since it uses only 8 kbps for the codec which translate to only 1 KB/s.

    Keep in mind that g729 is not free and you have to pay to use it, there are some exceptions that I don't know, you should read the documentations about that, I have to admit that I have it installed for test purposes and I found it on the Internet it's fairly easy to find using Google. Also keep in mind that usually ATA and VoIP phones will work in g711 you should check to change that to avoid Asterisk to do transcoding and uses CPU power. I'm not sure but the g729 licences states that you have to pay only when you transcode, so if your ATA already send a g729 stream to Asterisk and it's itself connected to your VoIP provider in g729, your should not have to use a license, you already paid it with the ATA and your provider paid it too, it's only the device that use the encoder that needs a license, but again I'm not sure.
    See this page for more informations: http://www.voip-info.org/wiki-Asterisk+G.729+Licensing

    As for your problem, describe the computer running Elastix and check to seed if your CPU is idle or if it's used 100%, I have a friend that have to play with it's boot loader to disable ACPI that mess with it's CPU.

    MageMinds
     

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