RL-HandsfreeManager fails to find MediaPlayer Dbus interface

[Robert-K]

Hey Alejandro, thanks for releasing this project!

I'm currently turning an old german rotary phone into a bluetooth hands free device, so I can use it to make and answer calls to my phone.

The setup is a Pi Zero W (1st gen, running Raspberry Pi OS Lite 2025-11-24) with a TP-Link bluetooth dongle (looks just like the Plugable one) and a USB soundcard.

Dialing and answering calls now works after carefully following the installation and configuration steps. I also found and fixed a small issue, see PR #3.

Media queries and audio however don't. speakertest works. I tried the suggested bcrm firmware fix to no avail.

Here are logs from some relevant services:

post@tischfernsprecher:~ $ service bluetooth status
● bluetooth.service - Bluetooth service
     Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; preset: enabled)
     Active: active (running) since Wed 2025-12-03 14:57:44 CET; 6min ago
 Invocation: 75c72d82c29d4a8f90a9e5bcdb044a1e
       Docs: man:bluetoothd(8)
   Main PID: 476 (bluetoothd)
     Status: "Running"
      Tasks: 1 (limit: 378)
        CPU: 798ms
     CGroup: /system.slice/bluetooth.service
             └─476 /usr/libexec/bluetooth/bluetoothd

Dec 03 14:57:40 tischfernsprecher systemd[1]: Starting bluetooth.service - Bluetooth service...
Dec 03 14:57:41 tischfernsprecher (uetoothd)[476]: bluetooth.service: ConfigurationDirectory 'bluetooth' already exists but the mode is different. (File system: 755 ConfigurationDirec>
Dec 03 14:57:42 tischfernsprecher bluetoothd[476]: Bluetooth daemon 5.82
Dec 03 14:57:43 tischfernsprecher bluetoothd[476]: Starting SDP server
Dec 03 14:57:43 tischfernsprecher bluetoothd[476]: Bluetooth management interface 1.23 initialized
Dec 03 14:57:43 tischfernsprecher bluetoothd[476]: Battery Provider Manager created
Dec 03 14:57:44 tischfernsprecher systemd[1]: Started bluetooth.service - Bluetooth service.
Dec 03 14:58:24 tischfernsprecher bluetoothd[476]: src/profile.c:record_cb() Unable to get hfp_hf SDP record: Host is down

post@tischfernsprecher:~ $ service raspberrylink status
● raspberrylink.service - RaspberryLink Server
     Loaded: loaded (/etc/systemd/system/raspberrylink.service; enabled; preset: enabled)
     Active: active (running) since Wed 2025-12-03 14:57:45 CET; 7min ago
 Invocation: 534bf094b4d84d668da67a78d49e3af2
   Main PID: 526 (raspilink-serve)
      Tasks: 9 (limit: 378)
        CPU: 19.449s
     CGroup: /system.slice/raspberrylink.service
             ├─526 /usr/bin/python3 /usr/bin/raspilink-server
             ├─642 /usr/bin/python3 /opt/raspberrylink/raspilink-bt-agent.py
             └─935 /usr/bin/bluealsa-aplay --pcm-buffer-time=1000000 00:00:00:00:00:00 --profile-a2dp

Dec 03 14:58:18 tischfernsprecher raspilink-server[636]: - Setting adapter  00:1A:7D:DA:71:15  name to  Tischfernsprecher
Dec 03 14:58:19 tischfernsprecher raspilink-server[636]: - Becoming discoverable and pairable...
Dec 03 14:58:19 tischfernsprecher raspilink-server[636]: - Bootstrap script complete.
Dec 03 14:58:19 tischfernsprecher raspilink-server[526]: 2025-12-03 14:58:19,682 - RL-Audio - INFO - Attempting to connect to previously-connected device: /org/bluez/hci0/dev_20_F0_94>
Dec 03 14:58:24 tischfernsprecher raspilink-server[526]: 2025-12-03 14:58:24,890 - RL-Audio - WARNING - Failed to connect to previously-connected device: /org/bluez/hci0/dev_20_F0_94_>
Dec 03 14:58:24 tischfernsprecher raspilink-server[526]: 2025-12-03 14:58:24,908 - RL-Audio - INFO - Starting Polling Thread
Dec 03 14:58:25 tischfernsprecher raspilink-server[526]: 2025-12-03 14:58:25,770 - RL-Server-Main - INFO - Starting WSGI server on 0.0.0.0:9098
Dec 03 14:58:26 tischfernsprecher raspilink-server[526]: 2025-12-03 14:58:26,229 - waitress - INFO - Serving on http://0.0.0.0:9098
Dec 03 15:01:56 tischfernsprecher raspilink-server[526]: 2025-12-03 15:01:56,538 - RL-Audio - INFO - Device connected: Pixel 6a with address C8:2A:DD:A0:42:E1
Dec 03 15:01:56 tischfernsprecher raspilink-server[526]: 2025-12-03 15:01:56,602 - RL-HandsfreeManager - WARNING - Failed to find MediaPlayer Dbus interface

Dec 03 14:57:41 tischfernsprecher systemd[1]: Starting ofono.service - Telephony service...
Dec 03 14:57:42 tischfernsprecher ofonod[484]: oFono version 2.16
Dec 03 14:57:44 tischfernsprecher systemd[1]: Started ofono.service - Telephony service.
Dec 03 15:02:00 tischfernsprecher ofonod[484]: AG supports the following HF indicator: 1
Dec 03 15:02:00 tischfernsprecher ofonod[484]: AG supports the following HF indicator: 2
Dec 03 15:02:00 tischfernsprecher ofonod[484]: AG wants indicator 1 enabled
Dec 03 15:02:00 tischfernsprecher ofonod[484]: Active map: 01
Dec 03 15:02:00 tischfernsprecher ofonod[484]: Service level connection established
Dec 03 15:05:18 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered
Dec 03 15:05:18 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered
Dec 03 15:05:26 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered
Dec 03 15:05:26 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered
Dec 03 15:05:29 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered
Dec 03 15:05:29 tischfernsprecher ofonod[484]: Reject SCO: Agent not registered

Do you have any idea what could be the culprit here?

[alejzeis]

Hi Robert, glad you've got some of it working! Unfortunately I haven't touched this project in some time. It seems you've applied all the fixes I know of.

Something that may be helpful: since I made this project there's been a new emergence in the Linux audio space: PipeWire, which acts as a front-end for applications to access PulseAudio, ALSA, JACK, etc.

This project uses ALSA, which can only be used by one program at a time. Most stuff nowadays uses PipeWire or PulseAudio instead of ALSA directly. The bluetooth stuff there is probably more stable, so I'd recommend looking into that.

I would try to see if you can get hands-free audio working manually: using the Raspberry Pi OS GUI to connect to the device and play audio. By default this should use pipewire or pulseaudio.

[Robert-K]

Thanks for the info! I've since switched to using an ESP32, which is more appropriate for the project anyways ^^