bad sound/audio quality on CX700 RRS feed

  • Question

  • Hi all,

    we currently have some enterprise voice users enabled and all of them are reporting that the voice quality is significantely worse then using the normal phone (Alcatel) to place a call. The other side is also reporting bad voice quality even when the other side is connected directly to the PBX (internal phone).
    It sounds like the caller is far away (like calling from Europe to the US 20 years ago).
    The network is low on utilization and between the phone and the mediation server and the mediation server and the mediagateway (Dialogic MDG4000) there is no firewall active.

    What are your experiences with voice quality?
    Any advice on how to find the problem?
    Does the CX700 or the Mediation Server has Voice active detection (VAD) enabled, where can I turn it off?

    Thanks & regards
    Tuesday, June 30, 2009 9:48 AM

All replies

  • Hello Edgar,

    I'd start with a monitoring server and making sure the CX700's are running the latest firmware.  You should also verify your OCS environment is patched and most importantly not running in a virtualized environment.  I like VMWare and use it on a fairly large scale, but I have seen the quality issues when running OCS on ESX, even with reserved resources and even dedicated resources.

    http://www.microsoft.com/downloads/details.aspx?familyid=E9F86F96-AA09-4DCA-9088-F64B4F01C703&displaylang=en - Deploying Monitor Server

    http://www.microsoft.com/downloads/details.aspx?FamilyID=565595be-6cf3-4a61-a1e4-12555749ca64&displaylang=en - Latest firmward for MOC Phone edition

    I'd also place a few test calls on the CX700 and MOC yourself in a few different scenarios to try to single out the issue
    * PSTN to CX700
    * CX700 to CX700
    * MOC to MOC - ruling out the 700
    * PSTN to MOC

    On the monitoring server pay attention to Network MOS for UC to UC and UC to PSTN.

    Hope this helps!


    Kevin Peters MCSE/MCSA/MCTS/CCNA/Security+ blog: www.ocsguy.com
    Tuesday, June 30, 2009 12:30 PM
  • Have you checked the firmware on the cx700 not all of them ship with the newest code and the older versions have some challenges
    Wednesday, July 1, 2009 1:28 PM
  • Hi Kevin,
    Hi Mitch,

    I´m glad we only have the Monitor Server virtualized.

    The CX700 has the newest firmware installed, also the Mediation Server and Frontend Server are up to date.

    The network MOC for UC to PSTN is 2,95. Is this a good value? What value do other people have?

    I also called a colleague today and he changed from his handset to his headset and we had a great improvement on the voice quality. Then I changed from handset to headset and it was just like a normal ISDN call.

    Then we changed our handset (without disconnecting the call) with an Alcatel Headset and guess what, the quality was still like a normal ISDN call.

    So my conclusion is that the handset is very buggy.

    Thanks for your help Kevin

    Best regards Edgar
    Wednesday, July 1, 2009 2:15 PM
  • Edgar,

    The best possible PSTN MOS score is 2.95, so that is very good.  For UC to UC the best quality should be 4.10.


    Kevin Peters MCSE/MCSA/MCTS/CCNA/Security+ blog: www.ocsguy.com
    Wednesday, July 1, 2009 2:49 PM
  • Edgar,

    The best possible PSTN MOS score is 2.95, so that is very good.  For UC to UC the best quality should be 4.10.


    Kevin Peters MCSE/MCSA/MCTS/CCNA/Security+ blog: www.ocsguy.com

    KP, I am having similar problem where Network MOS is record 2.95 but user still complaint voice bad voice quality.
    Below are some of the information i captured: -
    Audio Stream (Caller -> Callee)
     Inbound Report   True  Packets   40812
     Outbound Report  True  Packet Loss Rate 0.00 %

     Codec   x-msrta  Packet Loss Rate (Max) 0.94 %
     Sample Rate  8000  Jitter   2.00
     Network MOS  2.95  Jitter (Max)  5.00
     Degradation  0.00  Round Trip Time  205ms
     Degradation Jitter  0.00   Burst Density   0.00 %
     Degradation Packet 0.00   Burst Duration   0ms
     Bandwidth Est   99012000bps  Burst Gap Density  0.00 %
          Burst Gap Duration  813120ms

    Audio Stream (Callee -> Caller)
     Inbound Report   True   Packets   94888
     Outbound Report  True   Packet Loss Rate  0.00 %
          Packet Loss Rate (Max)  0.83 %

     Codec    x-msrta  Jitter    2.00
     Sample Rate   8000   Jitter (Max)   7.00
     Network MOS   2.95   Round Trip Time  205ms
     Degradation   0.00   Round Trip Time (Max)  214ms
     Degradation Jitter  0.00   Burst Density   0.00 %
     Degradation Packet  0.00   Burst Duration   0ms
     Bandwidth Est   98057700bps  Burst Gap Density  0.00 %
          Burst Gap Duration  1896240ms

    Tuesday, July 7, 2009 7:35 AM
  • This is just some additional information:
    I had bad audio quality with POE (Power over Ethernet) to the CX700. The far end had some hum.
    Solution 1: use the original Power supply. Solution 2: use another POE Switch.

    Thursday, July 9, 2009 8:57 AM
  • We have OCS on ESX and we have voice quality problems. But I thought that the voice stream is not going through the OCS at all. It thought it goes directly from communicator to communicator, only signaling should go through OCS.
    Correct? So how can OCS influence voice quality?

    thx & rgds Stiwi
    Friday, July 10, 2009 9:07 AM
  • Well you are correct that the media stream is peer to peer in a single person to person call, however all conference calls will go through the OCS server. and this is only internally. If you start doing PSTN calls then the mediation server is always involved, and if you start doing remote calls then the edge server will be involved much of the time (but not always). How ever some of the delay noticed when virtualized is in call setup and tear down. I have setup environments in both virtual and physical.
    And often times virtual works ok but once in a while during the day the call takes a while to establish, and or close. but again this is only peer to peer if I go into a conference then I can often see more delay in the voice at that point.

    Friday, July 10, 2009 12:51 PM