Plantronics DA55/DA60 provides exceptional sound quality & the flexibility to use any Plantronics headset (P or H range) with Vo IP Soft Phones. USB (Universal Serial Bus) port connection provides universal compatibility & independence from the PC’s soundcard, allowing the PC’s speaker, not the headset, to ring for call notification. Sound quality is digitally-enhanced with Plantronics proven Sound Guard Plus & Call Clarity technology, whilst Digital Signal processing (DSP) suppresses the echo sometimes experienced with Vo IP. Persono Pro software further improve a call centre agents experience of Vo IP & enables managers to easily measure & track compliance with European legislation on employee sound exposure.