Both promotional and transactional messages can be sent via SMS. Promotional messages are those sent in bulk, typically with marketing content. Transactional SMS messages are sent to individuals and are triggered in response to some action, such as a sign-up, purchase, etc.
Here is a link to detailed instructions for sending transactional SMS using our API: https://developers.sendinblue.com/v3.0/reference#transactional-sms-1.
To monitor sent transactional SMS messages in your SendinBlue dashboard, please follow this link: https://app-sms.sendinblue.com/.