Up to 30 days after they’ve been sent or received
You can view sent, received and scheduled messages in your SMS Overview in the 'SMS'-menu on the left-hand side of your Dashboard. Here you can select if you wish to see the overview of 'All messages', 'Received', 'Sent' or 'Scheduled'.
More than 30 days after they’ve been sent or received
For messages sent and received beyond 30 days (up to 1 year), you can export a CSV file. CSV files can be opened in spreadsheet applications - such as Excel. Go to your SMS Overview in the 'SMS'-menu on the left-hand side of your Dashboard and select 'Export'.
Within that overview, you can select the period, message type (sent and/or received), extra fields to export and the file delimiter.