Working as design.
Per models Plantronics.
Contains extract.
APV-6A/APV-62/APV-63 (Avaya EHS Cable) Product Information
Electronic Hook Switch (EHS) cables provide communication between your phone and Plantronics headset, enabling you to answer and end your calls using your headset call control button.
Compatibility Information
EHS cables are designed to work with specific phone models and Plantronics products. The table below provides the compatibility information for the APV-6A, APV-62, and APV-63.
EHS Cable Phone Make and Model Compatible Plantronics Product
APV-6A Part No. 83681-01
Also review attached Application note interoperability file, it contains CM and 46xxsttings.txt configuration that needs to be done and more details about EHS cable is required.