This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics 57250, Connection PC via USB, Wideband up to 6800Hz, Power source USB, Standard 12 keys, Microsoft Support Lync and Office Communicator, Handset and Speakerphone.
Make the evolution to PC communications simple with the new Calisto® 240 USB handset. With its portable size, new LCD display and integrated speakerphone, managing PC calls on-the-go has never been easier.