Bluetooth for Windows is something that could cause an issue since Windows has a general compatibility issues with Bluetooth audio devices.
However, if you decide to use Bluetooth between Konftel Ego and Windows laptop make sure to use the correct profile.
Stereo Bluetooth (Headphone) and also the hands free profile (headset).
You have to use the hands free profile to activate the microphone to be able to use it in communication clients. In many cases you can disable the profile that you don't want to use if Windows doesn't automatically select the correct one.