TR1 Headset Adapters for Avaya Partner Phones The TR1 (60590-01) headset adapter was originally designed for and packaged with the Plantronics CS55H wireless headsets. This headset was designed for use on a cordless phone with a single line coming in. In time we here at Headsets Direct discovered plugging the TR1 adapter into the extra AUX jack on the Avaya Partner phones … Continued