The Hands-Free Profile (HFP) 1.6 specification defines the minimum
set of functions such that a Mobile Phone can be used in conjunction
with a Hands-Free device (e.g. installed in the car or represented by
a wearable device such as a headset), with a Bluetooth® Link
providing a wireless means for both remote control of the Mobile
Phone by the Hands-Free device and voice connections between the
Mobile Phone and the Hands-Free device.
Compliance with this specification assures interoperability between a
Bluetooth enabled Hands-Free device and any Bluetooth equipped
Mobile Phone supporting this profile.