I tried everything ... I just can not get the button to work like i want. I want the button the headset to END Calls. The Headset is directly connected to my laptop with bluetooth. On my audio/speaker right below in Windows 10 I can use 2 options: Sennheiser MP PRO Stereo Sennheiser MP PRO Hand-free I selected Hand-Free, because then I can hear myself when dailing *777 (self test) I tried this: 1. Sennheiser Updater: New firmware uploaded (check!) 2. Installed: Sennheiser 3CXPhone Plugin (check!) (it did create a DLL: C:\ProgramData\3CXPhone for Windows\PhoneApp\Sennheiser3CXPlugin.dll) Did restart computer..did not help I did even installed HeadSetup...did not helped I did read the 3CX manual...did not helped https://www.3cx.com/docs/configuring-sennheiser-headsets/ I am out of options!