As Debian Buster package repositories have disappeared from debian mirrors as buster becomes an archived release, the default upgrade path for Wazo 23.05 is broken.
In order to support upgrade from 23.05 to newer bullseye-based releases, the wazo-dist-upgrade package has been updated.
That upgrade path also requires manually changing the default debian mirrors to alternative archive mirrors.
For example:
# /etc/apt/sources.list
deb http://archive.debian.org/debian/ buster main
deb-src http://archive.debian.org/debian/ buster main