When sending Voice and TextToSpeech messages, there are a handful or potential result codes (defines if the message was delivered successfully or a failure).

Status Result Explanation
Success Sent Ok Voice call received and answered successfully
Success AnswerPhone Voice call received and answered successfully by an answering machine/voicemail
Success Fax Number Voice call received and answered successfully by a fax machine or modem
Success Max Duration Voice call received and answered successfully and the Max Duration limit (LIM and/or LIMB) was reached
Failed No Answer Call unanswered within 60 seconds
Failed Busy Recipient responded with Busy tone
Failed Bad Audio Format Your submitted audio files are in an incompatible or corrupted format (should be WAV or MP3)
Failed Bad Number (NRD) Number is invalid (not owned by any network or carrier)
Failed Bad Number (OC) Number is invalid (recipient's network or carrier rejected the call)
Failed Bad Number (Unallocated) Number is invalid (recipient's network or carrier advises the number is unallocated/unused)
Failed Bad Number/No Answer (NUR) Number is invalid (the recipient's telephone equipment is disconnected)
Failed Invalid Voice Number (RP-Min) Mobile number is invalid (not enough digits for the supplied network/carrier)
Failed Invalid Voice Number (RP-Max) Mobile number is invalid (too many digits for the supplied network/carrier)
Failed Temporary Failure (CR) Recipient's network or carrier advises the number is valid but is experiencing a temporary fault
Failed Temporary Failure (NTF) Recipient's network or carrier advises the number is valid but is experiencing a temporary fault
Failed Call Timed Out Recipient's network or carrier accepted the call but failed to route or reject the call (no result provided)
Failed No Permit Record Internal TNZ error; contact TNZ Support