If you would like to export or backup SMS messages only (without doing a backup of whole database), please perform the following steps:
1. Go to web-GUI > menu Reporting.
2. Choose a desired folder for backup (Inbox/Sent items)
3. Select other reporting criteria (date to/from, output fields).
4. Click the "Generate report" button.
5. Export report to a file.
At the bottom of the report you will find 2 buttons: "Export to PDF" or "Export to CSV". Choose a export method of your preference.