Linphone doesn't switch my headphone to HSP/HFP

[Mauro]

I learn from https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/508522 that in recent Ubuntu releases the behaviour of Bluetooth headset profile handling changed, so that it's set to A2DP profile by default and automatically switched to HSP/HFP when a phone app needs to use the headset.

In Ubuntu 16.04 I could set the HSP/HFP profile on my Bluetooth haedset and this was remembered across disconnections and reconnections of the device.

In Kubuntu 20.04 my headset is set to A2DP profile whenever I (re)connect it, even if I previously set it to HSP/HFP profile.

This is really annoying because Linphone does not cause any switch and will simply work with an output-only device when the headset is currently connected in A2DP profile mode on start. The Mic of course won't work (Linphone will automatically choose another Mic device).

If I understand it correctly, the problem lies in Linphone that does not set the proper media.role, however is there meanwhile a workaround to restore the previous behaviour?

I tried to change /etc/pulse/default.pa adding auto_switch=false parameter to module-bluetooth-policy, so that the corresponding line is changed to:

load-module module-bluetooth-policy auto_switch=false

however this does not solve the problem that my headset is always reset to A2DP profile on reconnection and the HSP/HFP profile setting is not remembered.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linphone 3.12.0-3.1
ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
Uname: Linux 5.4.0-48-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.6
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Thu Oct 8 09:09:06 2020
InstallationDate: Installed on 2020-10-05 (2 days ago)
InstallationMedia: Kubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
ProcEnviron:
 LANGUAGE=
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SourcePackage: linphone
UpgradeStatus: No upgrade log present (probably fresh install)