The handsfree client is an implementation of the Bluetooth handsfree profile. This protocol is similar to the headset profile, but it provides more functions than the older headset profile. Originally, the handsfree profile was designed for use in car handsfree devices, but more and more common Bluetooth headset support the profile today. Modern linux provide ofono as modem manager. For the moment it is possible to connect the HFP and use external ofono frontends for managing calls.