The Polycom CX300 and similar Plantronics Calisto 540 (P540-M), snom UC600 are originally optimized for Microsoft Lync (Skype for Business) for Windows and Mac but can also be used with Linux. It shows up as a USB audio playback and recording device (this part works immediately out of the box) plus some USB HID (this needs to be made work; see below).
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