Jerky Audio

Discussion in '3CX Phone System - General' started by heathzap, Oct 11, 2008.

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  1. heathzap

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    On occasions I notice that our incoming voice message (on IVR) and music-on-hold audio is jerky. At first I thought the file sizes were too big so I reduced them down to <200k each. This didn't help. The server I'm running 3CX on is quite beefy - 4Gb RAM, plenty hard drive space and dual xeon processor. I do have some other stuff running on this machine but processor and RAM utilization is low. I am running 3CX on three ISDN lines ie 6 lines in total, thru a Patton box.

    Any ideas?
     
  2. galal202

    galal202 New Member

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    Hello and welcome
    if you use voip provider the problem will be: internet bandwidth
    and it could be codecs (because free 3CX version does not have g729)

    please send more information to help you
     
  3. heathzap

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    Tx for the response.

    I am using a Patton BRI box (http://www.patton.com/products/pe_products.asp?category=329) connected to 3 ISDN lines (i guess these are 128k, divided into two ie 64k each - so I get a total of 6 lines effectively) and my version of 3CX is a commercial license. I was lead to believe that the Patton box (4638) does all the hard work in converting the ISDN lines to SIP. So, this shouldn't put any strain on 3CX per se. I have also noticed that sometimes if I call someone it rings but loses voice when they answer. I am using Polycom 330 IP phones.
     
  4. galal202

    galal202 New Member

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    you're welcome
    I'm sorry I did not work before with your devices
    but in local lan you should not have any voice problems specialy your server is strong enough
    are you set the prefered codecs in all your devices to g729 ?
    some time (I do not why) when the call transefered or put in hold or sent to voicemail the codecs changed to g711
    are you use pbx deliver audio in your extesions ?if yes disable it
    are you use call recording feature? it cause all trafic should go to/from the server
     
  5. heathzap

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    Tx again! I have not looked at the codec issue yet. Are these set in the 3CX server AND the individual phones AND the Patton box? I'm not sure what you mean by the PBX delivering audio to the extensions although I did see this option on 3CX? I'll try disabling it though. We are not using call recording.

    I noticed another weird thing this morning: I received an email message notification with a WAV file attached. The WAV file is 597k but it is completely blank (ie media player plays it but it's blank)! And yet I have received other similar messages where I can listen to the WAV fiel no problem.

    Regards
    John
     
  6. heathzap

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    Ok...I tried setting my Polycom 330 phones to use g729 only (ie I set them to not use g711a or U) but then I couldn't dial out across 3CX and the Patton box. I'm not sure if 3CX has settings on this that I need to be mindful of (?) and the weird thing is that the Patton box seems default set to g729! The Polycom phones have a jitter setting for each of g729 and g711a and U. Maybe these need to be tweaked?

    These are the possible Polycom settings:

    G.729AB Codec Profile
    Payload Size 20
    Jitter Buffer Minimum 40
    Jitter Buffer Shrink 500
    Jitter Buffer Maximum 160

    Regards
    John
     
  7. mickp

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    As nothing is going across the internet there's no need to opt for g729 which is a high compression codec. I'd try going all G711a or u.

    Mick.
     
  8. galal202

    galal202 New Member

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    Hello,
    1-you have to set your prefered codec to g729 in patton and pollycom
    2-do not disable codec 711 but make it second prefered codec
    3-set use prefered codec only to no
    4-3cx has no relation for codec if you do not use pbx deliver audio
    5-you will find pbx deliver audio in each extension settings

    general advice:
    1-install fresh windows
    2-make a backup for your server using ghost or any other similar program
    3-install fresh 3CX
    4-again make a backup for your server using ghost or any other similar program
    5-make 3CX backup using 3cx backup tools
    so any time you can restore at the point you need
    6-any time you think you may make changes in the default settings and this changes is not in 3cx guide safe your time by restore it to factory defaults and reconifig it again carefuly
     
  9. galal202

    galal202 New Member

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    Hello Mick,
    for some reasonos specialy whe I use record calling feature I found G711 make some bad audio or echo on local lan calls
     
  10. heathzap

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    I spoke to someone at Patton and he also suggested we might look at VAD and silence suppression, since that might also cause a jitter on voice if too sensitive. The frustration on Patton is that only some of these settings are available via the web interface and specifically, the jitter and VAD settings are not. So I need to go figure how to use Telnet to access the box and see what this does. INteresting though that 3CX doesn't mention any of these issues in their Patton 4638 guide http://www.3cx.com/voip-gateways/smartnode-isdn.html.
     
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