One-Way Audio with AudioCodes and Encrypted Lync Media

This is a quick one: If you’re using media encryption with the latest MSBG 1000 firmware posted to the AudioCodes website, you might find yourself experiencing issues with one-way audio. Specifically, Lync users are periodically unable to hear PSTN callers. The issue is sporadic, and may appear or disappear as the call continues, although a hold/resume tends to fix it temporarily.

After doing some packet captures you will see a bi-directional RTP stream between the gateway and Mediation server, but the Mediation server does not actually pass any RTP packets to the Lync endpoint side because it is unable to decrypt the media.

This is a known issue in the 6.40A.037.009 firmware and can be resolved by upgrading to version 6.40A.059. You’ll have to call in to support to retrieve the newer firmware since the one with the issue is the latest posted to the AudioCodes website (and unfortunately very dated, seeing as it was released in May of 2012.) Happy upgrading.

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Comments from the Peanut Gallery

  1. JuMz

    How exactly do you download firmware from their site? I have logged in, and in the downloads, all I see is documentation, not firmware. What am I missing here? I have a Mediant 1000 MSBG.

  2. Prashanth K

    Hello Tom,

    We’re having this issue as well and are trying to determine which device is causing the issue. Most of the time, it appears to happen every 30 minutes and as you suggested a hold/resume fixes the issue temporarily. We have updated the M1KB to 6.40A.066 as per AudioCodes’ recommendation but the issue still persists. We’ve set the parameter related to re-key as well. Just wondering if you had to make any other changes.


  3. JuMz

    I also experience the problem as described by Prashanth with 6.40A firmware.

    Any suggestions?

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