[pulseaudio-discuss] HSP and HFP profiles for hands-free telephony

Mohammed Sha mohammed.sha at vvdntech.in
Fri Mar 22 04:33:10 UTC 2019

Hi All,

I am attempting to implement hands-free telephony on my board, I
successfully connected my android phone to the board via bluetooth module
in phone and media audio sharing mode.
I was able to play media files via bluetooth by this. But when a call
connected the bluetooth speaker works properly, i.e. I can hear what is
said on the Mobile Phone, but audio is not transmitted from Board to Mobile
Phone is not heard ( I guess there is some error in getting the data from
mic or in transmitting data from bluetooth device). I get the following log
message keeps appearing many times as soon as a call is initiated

"***Bluetooth: hci0 SCO packet for unknown connection handle 0***

***Bluetooth: hci0 sending frame failed (-27)***

***Bluetooth: hci0 sending frame failed (-27)***"

The microphone on the phone is also not functioning(after bluetooth
connection is established). Also in *hciconfig -a* it is found as follows

hci0:   Type: Primary  Bus: USB
    BD Address: 00:0E:8E:76:00:55  ACL MTU: 1024:8  SCO MTU: 50:8
    RX bytes:810924 acl:982 sco:18885 events:670 errors:0
    **TX bytes:528349 acl:530 sco:10271 commands:108 errors:111**
    Features: 0xff 0xfe 0x8f 0xfe 0xd8 0x3f 0x5b 0x87
    Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
    Link policy: RSWITCH HOLD SNIFF
    Link mode: SLAVE ACCEPT
    Name: mydevice
    Class: 0x2c041c
    Service Classes: Rendering, Capturing, Audio
    Device Class: Audio/Video, Portable Audio
    HCI Version: 4.2 (0x8)  Revision: 0x0
    LMP Version: 4.2 (0x8)  Subversion: 0x25a
    Manufacturer: Qualcomm

How can I solve this and implement proper hands-free telephony?
The Bluetooth device is connected via USB interface, Below is the device
package configuration,
pulseaudio --version

pulseaudio 11.1
 bluetoothctl --version
bluetoothctl: 5.49

ofonod --version

The steps I followed to setup connection are as follows

    $ hciconfig hci0 up
    $ pactl list sources short
    $ pactl list sinks short
    $ bluetoothctl
    agent on
    scan on
    scan off
    pair <address>

Thanks & Regards
*Mohammed Sha Ebrahim*
VVDN Technologies Pvt.Ltd
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