A: Up until about 6 months ago, Plantronics made a line of headsets called the Polaris series Headset. These headsets were designed to work with phones like the Nortel that have a built-in amplifier. Plantronics no longer manufactures the Polaris headsets because they came out with the A-10 Cable. The A-10 Cable allows any of their H-Series Headsets to work effectively with phones, which in the past, required the Polaris headset. However, the polaris cable is not designed to work with an H-Series headset because the circuitry is not compatible.