There is a cron to automatically cleanup old conversation. Ideally this cron should be executed every 30 seconds. The file to execute is `bin/clean_calls`
To use calls in Comunic, you need a WebRTCSignalExchangerServer, a small signal exchanging server written using NodeJS. You also need to modify your configuration file located at `config/overwrite.php` by copying and pasting commented configuration located at `config/calls.php` and make it fit your needs.