Test messages can be sent through the API by adding a flag or tag to the send. The specific format of this field depends on the API version (JSON, GET, POST, WebService, Mail) and can be consulted in the online documentation or in the PDF manual.
Messages sent as test (or test) will not be sent to the final recipients nor will deduct credits from the account. But they will be stored in the History of the account.
We recommend this type of submission for early integration tests, bulk sendings or simulated campaigns. In addition we recommend to perform the checks present in the SMS API integration recommendations and good practices.