> 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/receiving-messages.md).

# Receiving messages

### `deliver_sm`

Use `deliver_sm` to receive delivery receipts and inbound SMS.

### Delivery receipts

If you request delivery receipts in `submit_sm`, eCall forwards them through `deliver_sm`.

For delivery receipts, `esm_class` is `0x04`.

### Inbound SMS

If you configure inbound SMS forwarding in the eCall portal, eCall forwards received messages through `deliver_sm`.

This applies to leased receive numbers.

For inbound SMS, `esm_class` is `0x00` or `0x40`.

{% hint style="info" %}
Use `bind_transceiver` when you want to send messages and receive callbacks on one session.
{% endhint %}