Submits an SMS message (plain text, flash, Unicode, WAP Push, or long/concatenated message) to one or more destination numbers over HTTP. All parameters, especially message and url, must be URL-UTF-8 encoded before submission.

The response is returned as plain text in the format: <Error_Code>|<destination>|<message_id>. For multiple destinations, each result is comma-separated in the same order as submitted.

| Response Code | Meaning | |---|---| | 1701 | Success — message submitted. Response format: 1701\|<CELL_NO>\|<MESSAGE_ID>. Use the message ID to map delivery reports later. | | 1702 | Invalid URL — one or more parameters were missing or left blank | | 1703 | Invalid value in username or password | | 1704 | Invalid value in type | | 1705 | Invalid message | | 1706 | Invalid destination | | 1707 | Invalid source (sender) | | 1708 | Invalid value for dlr | | 1709 | User validation failed — safe to retry | | 1710 | Internal error | | 1025 | Insufficient credit — batch aborted at this destination | | 1715 | Response timeout — do not resubmit the same message | | 1032 | DND reject | | 1028 | Spam message |

Standard SMPP v3.4 error codes may also be returned where applicable. Apart from error code 1709, do not retry re-sending the message for any other error code (including SMPP v3.4 error codes).

Multi-destination behavior: if a request contains multiple destinations, the batch is aborted immediately on any error other than "Invalid Destination" — in that case the invalid entry is skipped and processing continues with the next destination. If the SMPP server goes down mid-request, the API retries a fixed number of times before aborting the batch at that destination (code 1709 appended to the response). If credit runs out mid-request, the batch is aborted at that destination with code 1025 appended.