Polycom VVX Hookswitch Mode setting reverts after the reboot which happens when a setting is saved (Settings, Basic, Preferences, Headset).
- Polycom VVX 300, 301, 400, 410
- Polycom Firmware (version 5.9.1.0615)
Note: Possibly affects other Polycom VVX devices also
As a workaround the firmware can be downgraded by 8x8 to an earlier version which is not affected.