MTNL (Mahanagar Telephone Nigam Limited), operating in the Delhi and Mumbai circles, is a major DLT (Distributed Ledger Technology) operator in India. Therefore, the error codes for bulk SMS sent through MTNL fall into two primary groups:
1.DLT Scrubbing Failures (6XX Series): These are mandatory, universal codes defined by TRAI for all operators (including MTNL).
2.MTNL Route/System Errors (Low Numbers & 9XX Series): These are specific codes returned by the MTNL SMSC or their internal system for reasons like subscriber status or delivery issues.
Here is a comprehensive list of known MTNL bulk SMS error codes.
MTNL SMSC Delivery & Route Errors (Low Codes)
These codes relate to the message delivery attempt to the recipient on the MTNL network.
| Error Code | Description / Meaning | Typical Action |
|---|---|---|
| 0 | Successfully Delivered | Message was successfully delivered to the handset. (Success) |
| 1 | Unknown Subscriber | The mobile number is permanently invalid, inactive, or not found on the network. |
| 2 | Service temporary not available | A transient network issue, leading to temporary unavailability. |
| 3 | Unexpected Data Value | Internal data error during transmission. |
| 4 | FWD SM Failure | No response received from the operator (a network timeout). |
| 5 | Unidentified Subscriber | The subscriber cannot be identified (similar to 1). |
| 6 | Absent Subscriber | The subscriber's handset is off or out of coverage (Temporary). |
| 8 | No Response of SM Delivery | No DLR (Delivery Receipt) status received. |
| 9 | Illegal MS (Mobile Station) | Subscriber's handset or SIM is restricted or failed authentication. |
| 10 | System failure (Network timeout) | General system timeout on the network. |
| 11 | Teleservices Not Provisioned | The recipient's subscription does not support SMS. |
| 13 | Call barred (Operator barring) | The recipient has barred the ability to receive messages. |
| 15 | SM Delivery fail (Subscriber busy) | The subscriber is busy for MT SMS. |
| 21 | Facility Not Supported | The network or subscriber equipment does not support the required function. |
| 99 | Memory capacity exceeded | The recipient's SIM or handset memory is full. |
| 100-104 | PLMN/HLR/VLR/MSC system failure | Broad codes indicating system-level failure in the core network components. |
MTNL System & DLT Compliance Codes (9XX & 4XX Series)
These codes are often returned by the Telemarketer (messaging provider) or the MTNL gateway itself for business and DLT rule failures.
| Error Code | Description / Meaning | Category |
|---|---|---|
| 434 | Insufficient Balance | The bulk SMS account does not have enough credit to send the message. |
| 436 | Duplicate Number within 30 Min | The same message was submitted to the same number too frequently. |
| 437 | Inactive Account | The bulk SMS account is suspended. |
| 438 | Account Expired | The bulk SMS account validity has expired. |
| 951 | Number Blacklisted | The mobile number is on an internal blacklist (e.g., high spam complaints). |
| 952 | DND Rejected | The message was blocked due to DND preferences (Universal DLT Code: 650). |
| 953 | Invalid Senderid | The Sender ID is invalid or not DLT registered (Universal DLT Code: 620). |
| 954 | Invalid Number | The mobile number format is incorrect. |
| 956 | 9p.m to 9a.m | Promotional message sent outside permitted hours (Universal DLT Code: 651). |
Universal DLT Scrubbing Failures (6XX Series)
MTNL must return these codes if the failure is related to a mismatch in the DLT registration data.
| Error Code | Status Name (Universal) | Description / Meaning |
|---|---|---|
| 601 | ENTITY_NOT_REGISTERED | Your organization is not registered on the DLT platform. |
| 602 | ENTITY_INACTIVE | Your DLT registration is inactive. |
| 610 | TELEMARKETER_NOT_REGISTERED | The messaging provider is not registered/linked. |
| 620 | HEADER_NOT_FOUND | The Sender ID is not registered on DLT. |
| 623 | PEID_NOT_MATCHED_WITH_HEADER | The Sender ID is not linked to your Entity ID. |
| 630 | TEMPLATE_NOT_FOUND | The Template ID is missing or incorrect. |
| 633 | TEMPLATE_NOT_MATCHED | The message content does not exactly match the approved template. |
| 650 | PREFERENCE_NOT_MATCHED | The message was blocked due to recipient DND settings. |
| 670 | SCRUBBING_FAILED | General DLT system exception. |