To backup the configuration made by users/ voicemail files you should:
- backup the database
- backup the directory where voicemail messages and music on hold files are stored. This is set in $target_path from config.php from web folder.
- backup the configuration directory of yate (the majority of files will be restored on a new install) but there is one or two files that are modified depending on user configuration. This is set in $conf_path from config.php from web folder.