The SMS Broadcast System (SBS) can be accessed and administered via SFTP or web UI. SFTP is generally used for automated back-end system integration (CRM, scheduling systems, etc.), but some advanced users prefer it as well.
Once logged into the SBS SFTP server, sending a broadcast is as simple as uploading a properly formatted .CSV file with the broadcast information (messages, numbers, send times, parameters, etc.). Processed files and reports can be found in their respective SFTP directories.