See TNZ API documentation: REST API, SOAP API, .NET Library, HTTP/S API, SMTP API
REST API MessageTypes: SMS, Email, Fax, Voice, Text-to-Speech (TTS)

APIs perform only simple form validation on receipt of your API call; it won't validate the content of your message, the Authorization HTTP header, or the Sender/APIKey validity when accepting the call. These are validated by our authentication engine after receiving the API call and reported to the API user's administrator as an email to the listed 'API Error Email Notify' email address (viewable in your Dashboard login). This is to achieve optimum resiliency and speed, and to provide a layer of protection against API brute force attacks.

When submitting messages to the REST API, possible rejection codes are:

MessageType Result Error Message Description
All Success   API submission accepted. Use a GET Poll or Webhook to track message delivery. If the message fails authentication, check your Error Email Notify email address.
All Failed Error occurred while creating job Server-side error. Try again, or contact us if the error persists.
All Failed Missing Sender Empty 'Sender' field, empty Authorization header, or your API call is malformed and we can't find the 'Sender'
All Failed Missing APIKey Empty 'APIKey'
All Failed Invalid sender format 'Sender' is not an email address
All Failed Unauthorized Your Authorization token is incorrect or missing
All Failed Missing message data Empty 'MessageData' field
All Failed Missing or empty destinations Target(s) not found
All Failed Error - Could not find any valid destination(s). No valid targets found in the Destination section, ie. if MessageType is SMS, there is no mobile number listed as a Recipient in 'Destinations'
All Failed WebhookCallbackURL must start with https:// You will need to include the full path including the https:// prefix in your custom WebhookCallbackURL value (http:// is not supported)
Email Failed Missing or empty message body. Please specify MessagePlain or MessageHTML Empty MessageData.MessagePlain field and/or MessageData.MessageHTML field
SMS Failed Message(s) NOT found GET Poll is unable to find messages (result and reply tracking)
SMS Failed Missing or empty message Empty MessageData.Message field
Fax Failed Missing file name on file x MessageData.Files listed without a valid 'Name'
Fax Failed Missing file data on file x MessageData.Files listed without valid 'Data'
Fax Failed Missing fax contents - Empty or missing message & file fields MessageData.Message and/or MessageData.Files fields are not found
Voice/TTS Failed Missing message to people Empty MessageData.MessageToPeople field
Voice/TTS Failed Missing tone on keypad x MessageData.Keypads are listed without a corresponding 'Tone' value
Voice/TTS Failed Invalid tone on keypad x. Tone must be between 0~9 MessageData.Keypads.Tone is listed but is out of the valid range (value must be 0-9)
Voice/TTS Failed Missing RouteNumber/Play on keypad x MessageData.Keypads are listed without corresponding 'RouteNumber' and 'Play' fields
Voice/TTS Failed Invalid RouteNumber format on keypad x MessageData.Keypads.RouteNumber exists but the route number is invalid (or incorrectly formatted). It must be greater than 9 digits and numeric.