https://www.bluetooth.com/specifications/specs/hands-free-profile-1-8/

The Hands-Free Profile (HFP) specification defines a 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.

这里面有讲到蓝牙耳机可以通过蓝牙给手机发AT+CHUP指令挂断电话。