Cut-offs on an VoIP Network

Discussion in 'VOIP' started by R. Roe, Feb 11, 2004.

  1. R. Roe

    R. Roe Guest


    I've been working with a company that has 4 sites - all connect back on
    Frame relay to a host location where they are handed calls from a NEC
    Model IPS PBX; The Frame connections are termed on a Cisco 3620 router -
    the SP frame round trip times are < 22ms consistently; However we
    constantly get portions of the voice conversation missing, or have a
    "darth vader" sound on the conversation; We are running LLQ and have
    separate non-burst PVC for voice and data - The data side looks real
    healthy, but can't get ahold of anyone from NEC that has any input -

    Does anyone have a URL or help that can point me in the right direction
    for troubleshooting?


    R. Roe, Feb 11, 2004
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  2. R. Roe

    SPD Guest

    My network is little different but I have similar
    problems. Search Cisco's site for "Choppy voice".
    There are a few documents that talk about these

    In my case the problems appear going through a
    2620XM gateway to a Verizon DMS100 switch. In this
    case you can see counters of call statistics on
    the 2620. Look for the early, late and lost frames.
    If these are incrementing then chances are the
    playout buffer parameters need to be tuned.

    -good luck,
    SPD, Feb 11, 2004
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  3. R. Roe

    SPD Guest

    SPD, Feb 11, 2004
  4. R. Roe

    R. Roe Guest

    Thanx Steve!
    R. Roe, Feb 12, 2004
  5. R. Roe

    Pete Harris Guest

    the SP frame round trip times are < 22ms consistently; However we
    The "darth vader" effect is usualy caused by poor echo cancellation.
    Look at those places where packeted voice is converted to or from
    legacy phone circuits. When you have echo with longer latencies you
    hear an actual echo, but when if the latencies are short (like less
    than your 22msc), echo sounds like you're speaking through a tube.

    - Pete
    Pete Harris, Feb 13, 2004
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