SMS Delivery Error Codes Reference
These codes correspond to standard SMPP/GSM protocol error statuses returned by operators. You will find them in the details of each message under Reports > History.
| Code | Name | Meaning | Recommended Action |
|---|---|---|---|
| 1 | Unknown Subscriber | Unknown network number (terminated or never assigned) | Remove the number from your base |
| 5 | Unidentified Subscriber | Number not recognized at time of sending | Recheck number, try again later |
| 6 | Illegal Subscriber | Number blocked or not allowed to receive | Remove the number from your base |
| 11 | Teleservice Not Provisioned | The SMS service is not activated on this line | Remove the number from your base |
| 20 | Subscriber Busy for MT SMS | Terminal temporarily unavailable | The message will be retried automatically |
| 21 | Facility Not Supported | SMS incompatible terminal or line | Remove the number from your base |
| 27 | Absent Subscriber | Terminal off or out of coverage | Automatic retry until timeout |
| 29 | System Failure | Technical error on the operator network side | Contact support if persistent |
| 50 | Sender ID Rejected | Sender ID not recognized/not validated for this operator | Check Sender ID registration |
| 69 | Message Filtered (Anti-Spam) | Content blocked by operator spam filter | Review message content |
This list is not exhaustive. For any codes not listed here, contact support with the affected message ID.