> For the complete documentation index, see [llms.txt](https://developer.ecall-messaging.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.ecall-messaging.com/api-references/smpp/sending-sms.md).

# Sending SMS

### `submit_sm`

Use `submit_sm` to send SMS messages.

Only mandatory parameters are supported.

Optional parameters are ignored.

### Supported mandatory parameters

| Parameter             | Allowed values                                                                                         |
| --------------------- | ------------------------------------------------------------------------------------------------------ |
| `service_type`        | `""`, `"CMT"`, `"CPT"`                                                                                 |
| `source_addr_ton`     | `0`, `1`, `2`, `5`                                                                                     |
| `source_addr_npi`     | `0`, `1`                                                                                               |
| `source_addr`         | Up to `16` characters, or empty to use the default eCall sender                                        |
| `dest_addr_ton`       | `0`, `1`, `2`                                                                                          |
| `dest_addr_npi`       | `0`, `1`                                                                                               |
| `dest_addr`           | Up to `16` characters                                                                                  |
| `esm_class`           | GSM features: `00XXXXXX`, `01XXXXXX`; message type: `XX0000XX`; messaging mode: `XXXXXX00`, `XXXXXX11` |
| `registered_delivery` | SMSC delivery receipt: `XXXXXX00`, `XXXXXX01`, `XXXXXX10`                                              |
| `data_coding`         | `XXXXX0000`                                                                                            |

### Ignored mandatory parameters

| Parameter                 | Note                                                 |
| ------------------------- | ---------------------------------------------------- |
| `protocol_id`             | Ignored                                              |
| `priority_flag`           | Ignored. Contact support if you need prioritization. |
| `replace_if_present_flag` | Ignored                                              |
| `sm_default_msg_id`       | Ignored                                              |

{% hint style="info" %}
Use an empty `source_addr` when you want the default eCall sender.
{% endhint %}