> ## Documentation Index
> Fetch the complete documentation index at: https://docs.invoca.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Can I Apply Signals or Marketing Data to Multiple Calls Using the Signal API?

> Not in a single request — the Signal API applies data to one call at a time, though you can send up to 100 requests per minute.

**Applies to:** Customers who want to apply marketing data attribution (Signals or Marketing Data) to multiple call reports

## How the Signal API applies data

The Signal API applies Signals and/or Marketing Data (custom data fields) to a specific call (transaction) that has already occurred, using a POST request with:

1. **Call reference** — the Call Record ID, Transaction ID, or Call Start Time that identifies the call.
2. **Signals or Marketing Data** — the data to apply.
3. **OAuth token** — required for authentication.

```http theme={null}
POST /signal HTTP/1.1
Authorization: Bearer <oauth_token>
Content-Type: application/json
```

```json theme={null}
{
  "call_record_id": "<call_record_id>",
  "signals": ["<signal_name>"],
  "marketing_data": {
    "<field_name>": "<value>"
  }
}
```

## Things to keep in mind

* **One call per request** — applying data to multiple calls in a single request isn't supported. Send a separate request for each call.
* **Rate limit** — up to 100 requests per minute.
* **Backlog risk** — sending the maximum number of requests in a short window can create a processing backlog and delay when data is applied.

To avoid a backlog, spread requests out over time or send them in manageable batches rather than all at once.

## Where to go next

* [Can I Modify a Call Record Before the Call Ends?](/s/article/modify-call-record-before-call-ends)
* ["Call Must Be Present" Error on the Signal API](/s/article/call-must-be-present-error-signal-api)