Calls no audio but touch-tones work

What application is this relating to?

Calls

What problem did you encounter

Call established, no audio

What is the actual behaviour?

Call established, but no audio

What is the expected behaviour?

Call established, with audio working

How to reproduce

Call from a phone to the devkit, answer the call, cannot hear any audio. Pushing buttons on the devkit sounds touch-tones to the other phone, but no spoken words or any sound can be heard from the microphone.

Which version did you encounter the bug in?

• I compiled it myself. If you compiled the application from source please provide the git revision via e.g. by running git log -1 --pretty=oneline and pasting the output below.

• I used a precompiled Debian package. Please paste the output of dpkg -s <package name> below.

• I used a prebuilt flatpak. Please paste the output of flatpak info <application-id> below.

• I used something else (please elaborate).

Package: calls
Status: install ok installed
Priority: optional
Section: comm
Installed-Size: 324
Maintainer: Bob Ham <rah@settrans.net>
Architecture: arm64
Version: 0.0.1~154.gbpee126b
Depends: libc6 (>= 2.17), libglib2.0-0 (>= 2.43.4), libgsound0 (>= 1.0.1), libgr
Description: Make and receive PSTN phone calls
 A GTK+ user interface for PSTN phone calls using oFono.
Homepage: https://gitlab.gnome.org/Community/Purism/calls

What hardware are you running on?

• amd64 qemu image
• Librem5 devkit
• other (please elaborte)