Comment 32 for bug 1871794

From what I can gather this is not a function of the headset or Bluetooth device, but it's a function of firmware differences in the host side Bluetooth adapters.

For example, I have a Sony WH-1000MX3.

I have a USB dongle adapter that does not work in the HSP/HFP mode. When selecting the mode the active profile throws various errors then returns to the "off" PulseAudio/ALSA profile.

lsusb on the CSR USB dongle.
```
Bus 001 Device 003: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
Device Descriptor:
  bLength 18
  bDescriptorType 1
  bcdUSB 2.00
  bDeviceClass 224 Wireless
  bDeviceSubClass 1 Radio Frequency
  bDeviceProtocol 1 Bluetooth
  bMaxPacketSize0 64
  idVendor 0x0a12 Cambridge Silicon Radio, Ltd
  idProduct 0x0001 Bluetooth Dongle (HCI mode)
  bcdDevice 88.91
  iManufacturer 0
  iProduct 2
  iSerial 0
  bNumConfigurations 1
```

I also have an Intel Bluetooth/WiFi 802.11ac card (Bluetooth is on the USB bus), that does support the HSP/HFP mode, abet with noticeably reduced audio quality. I think there is a separate bug in launchpad tracking the audio quality issues of that mode though.

header for `lsusb -v` on the Intel card.
```
Bus 001 Device 005: ID 8087:07dc Intel Corp.
Device Descriptor:
  bLength 18
  bDescriptorType 1
  bcdUSB 2.00
  bDeviceClass 224 Wireless
  bDeviceSubClass 1 Radio Frequency
  bDeviceProtocol 1 Bluetooth
  bMaxPacketSize0 64
  idVendor 0x8087 Intel Corp.
  idProduct 0x07dc
  bcdDevice 0.01
  iManufacturer 0
  iProduct 0
  iSerial 0
  bNumConfigurations 1
```

lspci on the intel card
```
04:00.0 Network controller: Intel Corporation Wireless 7260 (rev 73)
 Subsystem: Intel Corporation Dual Band Wireless-AC 7260
 Flags: bus master, fast devsel, latency 0, IRQ 96
 Memory at f7600000 (64-bit, non-prefetchable) [size=8K]
 Capabilities: <access denied>
 Kernel driver in use: iwlwifi
 Kernel modules: iwlwifi
```