Running 14.0.10 (141024). Problem started about a month ago. May be coordinated with corporate upgrade to Skype for Business, which I recently became aware is being rolled out.

During a group call, volume constantly increases to maximum, requiring constant adjustment back to original volume. Very frustrating!

I'm not positive, but this seems to be related to either people joining or leaving the call, or possibly someone else adjusting their volume. Sometimes this happens every 20 to 30 seconds, sometimes it stops for many minutes. Tends to happen a lot near start of call or end, which is why I suspect it's people leaving or entering or adjusting volume.

AFAIK, running most recent version of Mac Lync client, upgraded relatively recently, in 2015.

Hi,

Did the issue also happen for other Mac Lync users/Windows Lync users or just happen for this Mac computer?

If the issue only happen for Mac Lync client, please try to uninstall it completely and install it again to test it.

Please also check if it is possible about the conflict of other software.

The next version of Office for Mac will be released this year, the Skype for Business for Mac client should be included in it.

From http://blogs.office.com/2014/10/31/new-outlook-mac-available-office-365-customers/

In the first half of 2015 we will release a public beta for the next version of Office for Mac, and in the second half of 2015 we will make the final release available.

Best Regards,
Eason Huang