Sennheiser BTD 500 USB Notice D'emploi page 7

Pairing to another headset
Activate pairing mode on your Bluetooth headset.
Plug the adapter into the USB port. The LED lights up
blue for 4 seconds.
Within this 4-second period, remove the adapter from
the USB port and then plug it back in. The adapter
switches to pairing mode and connects to your
Bluetooth headset.
0
4s
6
4s