> 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/error-codes.md).

# Error codes

In addition to the standard SMPP `command_status` values, eCall defines this custom error:

| Code                  | Value        | Description                                                      |
| --------------------- | ------------ | ---------------------------------------------------------------- |
| `ESME_RBILLINGFAILED` | `0x00000401` | SMS billing failed because the account has insufficient credits. |

{% hint style="warning" %}
Check account credits when you receive `ESME_RBILLINGFAILED`.
{% endhint %}