I have a headset from Plantronics that came with a connector.  Rather than plug the headset's speaker and microphone mini-connectors into the same on the computer, they plug into this adapter which in turn plugs into the computer's USB port.  Are these USB connectors available separately?  It says Plantronics DSP Adaptor-01, PLT-DSPadapter-01(B), N10687 Z109 on the device.

Thanks in advance.

Jeff