| Error Code | Error Description |
| 5001 | Invalid inbox message index |
| 5002 | Invalid message item index |
| 5003 | Read message error |
| 5004 | Cannot check PDU mode support |
| 5005 | Modem does not support PDU mode |
| 5006 | Cannot connect to modem for reading message |
| 5007 | Read message command error (Port not open) |
| 5008 | Read message command error (Timeout) |
| 5009 | Invalid response to read message command |
| 5010 | Read message error |
| 5011 | Invalid read message type option |