Does anyone have suggestions for the following problem? The server is at v12 Service Pack Update 6 Build 36097.670, but we were testing the updated Mac client before upgrading to Build 37098.738. Symptoms: When answering a call using 3CXPhone for MAC version 1.0.41, the volume on the microphone of a USB device gets set to zero in System Preferences on OSx Mavericks 10.9.1. The mic volume is unaffected in 3cx softphone properties. To reproduce: Answer a call (any call as far as I can tell) when a usb headset is present and watch the microphone volume get set to 0 in System Preferences. Troubleshooting steps performed: -Used the same headset (Plantronics) and installed 3CXPhone for MAC on a different computer. Version 1.0.28 worked as expected, but upgrading to 1.0.31 or 1.0.41 reset the microphone volume when answering a call. -Used a different headset on original computer (OSx Mavericks 10.9.1) and problem persists. -Uninstalled version 1.0.31 and installed 1.0.28 and problem is resolved. However, as soon as I upgraded to version 1.0.31 or 1.0.41, the problem resumed. Since the server is pushing 1.0.41, users have no choice but to upgrade. -Used the same headset on Windows 8 computer with 3CXPhone version 12.0.36097.0 and there was no problem with mic volume. -We have over 100 Windows 3CXPhone clients connected to this server that have never had this issue. Only Mac clients.