Can the device be connected to another device via Bluetooth? (e.g. laptop) If yes, I don't see any problem as long as the corresponding drivers for the device are available on Windows or can be installed.
Long: According to the manual, the 6867i does not have Bluetooth - otherwise you would not need to retrofit a BT adapter. A USB port is also not available. Even if there were, the adapter would not work without the appropriate support from the phone's firmware.
Solution according to the manufacturer's manual: Buy a suitable wireless hardware set :-)
"Users with wireless headsets that support DHSG/EHS can now connect directly to the 6867i - without having to purchase additional adapters or cables. adapters or cables."
