What is in a backup?

The database and the configuration: settings, certificates, uploaded sounds and music on hold, plugins and the key that decrypts stored secrets. Call recordings and faxes are not included. A backup is made every night, and old ones are removed after the number of days set below.

Keep downloaded backups safe: they hold every password and secret key of this system.

A restore replaces the present data with the data in the backup, and anything since then is lost. Services restart, and calls in progress drop. A backup of the present state is made first, and it is put back if the restore fails.