One Way Audio on internal Lync to Lync calls AND PSTN to internal Lync. RRS feed

  • Question

  • We have Lync 2010 Server On Prem. Our users have Lync 2010 Client on W7 computers. And using Lync soft phones on their computers. We are also using Dialogic Media Gateways. We have 850 Lync users. The problem is affecting about 5% of our employees.

    Some users, some of the time have one way audio with Lync to Lync calls while internal (we do have edge servers and federation, which have not been a problem with one way audio). Some of the same users and other users, have one way audio when an outside person calls internally. Placing all of these calls on hold and resuming the call, fixes the issue (fixes=they are able to hear each other on both ends). Or unplugging their headset and plugging it back in, brings the audio back (because this places the call on hold and then resumes the call).

    We have run many Wiresharks and traced calls on the server and cannot find the cause for these issues or anything to explain why it happens some of the time with some people.

    Has anyone run into this issue? Any and all ideas are welcome. Please let me know if you would like more information.

    Thank you.

    Wednesday, May 14, 2014 3:45 PM


All replies

  • In which direction is the audio not working? If its always on the transmit side for the user in question I would start by eliminating the headset\local audio as a potential cause. I have seen some strange (similar) behaviour when the end user has multiple audio devices.

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    Lync Sorted blog

    • Edited by PaulB_NZMVP Wednesday, May 14, 2014 5:23 PM
    Wednesday, May 14, 2014 5:23 PM
  • When an outside caller calls in, the internal user cannot hear them, but the outside person can hear the Lync user. When it happens Lync to Lync, it is the person receiving the call, that cannot hear the other person. I have tried multiple different headsets, troubleshooted with different audio drivers and using speaker phone and I am able to reproduce the issue.

    Wednesday, May 14, 2014 6:21 PM
  • You can refer below link {it's same issue}

    Please remember, if you see a post that helped you please click "Vote As Helpful" and if it answered your question, please click "Mark As Answer" Mai Ali | My blog: Technical | Twitter: Mai Ali

    Wednesday, May 14, 2014 7:42 PM
  • Sorry, but this is not the same issue. The above forum says the fix was to change the audio device on the 'outside users computer'. In my case, there is not outside user computer, these are cell phone or a landline.

    We do have the issue of internal Lync to Lync calls (they have the same hardware, software and drivers).

    Hope that helps to clarify.

    Thursday, May 15, 2014 7:11 PM
  • Hi,

    Please also update to the latest version for the issued Lync clients and then test again.

    Best Regards,

    Eason Huang

    Eason Huang
    TechNet Community Support

    Wednesday, May 21, 2014 3:06 AM
  • Hi,

    I have the most up to date versions of both Lync 2010 and Lync 2013 clients for users installed. The Lync Servers are also up to date.

    Wednesday, May 21, 2014 1:00 PM
  • Hi all,

    We have Lync 2010, Sonus gateways, dell hardware and polycom devices. Everything gets patched every few months.

    In the past few months i've done nothing but chase down a few similar issues so i thought it might help someone if i updated the forum posts that i had searched for in my quest for answers :)

    1. One way audio when a call is transferred

    When issues were initially reported for some users we discovered that if a user had an out of date NIC card driver and called a Lync user that then transferred them in a specific way they had one way audio.
    For example:

    • I call you, I have an old NIC card driver
    • You consult transfer me to someone using the 2nd call window/active transfer button (the person you just called to check their availability)
    • When the call is transferred I can hear audio but the final recipient of the call can't hear me
    • The fix was to update the NIC card driver and re-recreate the profile

    2. Bad call quality and random call disconnections

    We logged tickets with our telco and WAN provider and found that they were ropping the QoS tags for voice traffic and didn't realise.

    We also had random issues where telstra changed the wideband codec on SOME towers so calls that originated from those towers had no audio in both directions.

    2. Random call disconnections or one way audio when a caller is placed on hold

    We were not able to re-create this issue on demand but opened a ticket with Microsoft, Telstra and Sonus. To collect logs we:

    • Mirrored the port on the sonus and pointed it to wireshark
    • Installed wireshark on a user's PC that reported the issue regularily
    • Used LX to capture logs from the sonus/sbc
    • Used the lync logging tool to capture logs from the front end

    When we had the logs we found that there was a race condition in the PCAP file from wireshark. We were also able to confirm that it wasn't the users device becuase we could see in wireshark that audio was only one way. The support techs from sonus advised:

    "I think I see the cause of the "race" condition: there is a Message Translation Table to translate SIP 183 to SIP 180.  What is happening is Lync is sending numerous SIP 183 messages and each time the SBC translates it to SIP 180 with Require: 100rel; which causes Telstra to send a PRACK.  This happens so many times that Telstra declares a "race" condition and I suspect that is why audio is not passed from them.


    I suggest that you make this change to the Message Translation Table "183 to 180" -> Send Message to "No on Subsequent".  What this means is the SBC will translate the first SIP 183 to SIP 180 and then will not translate any other SIP 183 messages for the current call.  This should eliminate the "race" condition."

    Making this change appeared to have resolved the issue for us. I hope that helps someone :)

    ----- More info -----

    Following is a list of things we tried to re-create the one way audio issue:

    • Patched Lync server, handsets, gateways and SBA’s
    • Resolve any small client side issue like – group policy being incorrect for that machines, firewalls being on, updates not applying, bad cables etc
    • Turn off local machine firewalls
    • Install all the latest windows and office updates
    • Disable team calls
    • Replace the wireless and Bluetooth headset with a wired USB headset
    • Try transferring the call to see if audio is restored
    • Try putting the call on and off hold a few times to see if audio is restored
    • Try answering the call on the computer and not the headset/ try answering only on the headset
    • Update NIC and PC BIOS firmware
    • Tested calls inbound from Telstra, Virgin, Vodafone and Optus mobiles
    • Stacked up many calls at a time, generated load, tested when the network and gateway were busy
    • Changed the trunk configuration per this blog

    Some other posts that might help if you're desperate:

    People with similar issues where encryption was the culprit:


    People with similar issues where ethe firewall was the culprit:


    People with similar issues where software updates were the culprit:


    Where the issue was resolved by removing USB hubs & booting the machine with no USB devices plugged in:


    People who had the same issue in 2013:

    • One way audio:
    • Comment saying one way audio was resolved by disabling SIP UPDATE method between the SBC and Lync
    Wednesday, October 28, 2015 12:56 AM
  • We have the same occasional problems(Lync 2013, Sonus SBC 1000), that i've been unable to track down. I'm also unable to reproduce the issue myself, and capture a clean log of it.

    However, the people at our company's call-center have issues multiple times a day.

    Your solution could very well be my solution. Now: I have no "message translations"(under "Telephony Mapping Tables" > "Message Translations"). It's empty. Would be be so kind to supply some more information on how this is set up? Screenshot maybe?

    And on which Call Routing Tables do you have the "Message Translation Table" configured? (from SIP provider, or from Lync or both)

    Friday, April 1, 2016 10:56 AM
  • This was firewall blocking ports.
    Wednesday, August 1, 2018 7:44 PM