Quick Disconnect (QD) headsets require an amplifier or audio processor also referred to as a bottom cable in order to work. The QD headset has no way to connect to a computer or phone on their own and require the amp or audio processor for sound. Some phones require a bottom cable that works specifically with their brand, thus different bottom cables for various phones, but all will connect to the headset using the QD cord.
The Poly Quick Disconnect (QD) is a proprietary connector featured on “H” and “P” series headsets. A QD connection also enables you to place a call on hold by simply disconnecting the headset at the QD during a call. It enables you to walk away from the telephone without having to remove the headset. See Direct Connect Cables from Poly for that will work with any Poly "H" or "P" series headset top.