A Bluetooth profile (mode) designed to enable a two-way wireless speaker-phone to be used with a Bluetooth phone.
Although it can be used with a desktop speaker-phone accessory, its most common use is with car kits. A Bluetooth car kit will use HFP to connect to a Bluetooth phone, allowing phone calls to take place via the car's audio system (or an installed speaker) while the phone stays safely in a pocket or purse.
HFP is one of the most common Bluetooth profiles. Nearly all phones support it, including ones that do not support Headset Profile (HSP). Since all modern Bluetooth headsets support both HSP and HFP, phones without HSP can still use Bluetooth headsets via HFP.
A newer profile called TMAP (Telephony and Media Audio Profile) is designed to replace both HFP and HSP. TMAP is part of LE Audio, the newer standard for all kinds of audio over Bluetooth.
See: LE Audio
HFP does not support stereo audio.