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# detect

> Detect answering machines, fax tones, or digits on a call.

[detectaction]: /docs/server-sdks/reference/typescript/relay/actions

[calling-call-detect]: /docs/server-sdks/reference/typescript/relay/call#events

[call-events]: /docs/server-sdks/reference/typescript/relay/call#events

Start audio detection on the call. Detects answering machines, fax tones, or
DTMF digits. Returns a [`DetectAction`][detectaction]
that resolves on the first detection result or when the operation finishes.

> **Note**
>
> The `DetectAction` resolves on the **first detection result**, not when the
> detect operation finishes. This means `await action.wait()` returns as soon as
> a result is available.

> **Info**
>
> This method emits [`calling.call.detect`][calling-call-detect] events. See [Call Events][call-events] for payload details.

## **Parameters**

**`detect`** `Record<string, unknown>` — required

Detection configuration object.

---

**`detect.type`** `string` — required

Detection type. Valid values:

* `"machine"` -- answering machine detection (AMD)
* `"fax"` -- fax tone detection (CNG/CED)
* `"digit"` -- DTMF digit detection

---

**`detect.params`** `Record<string, unknown>`

Type-specific detection parameters.

---

**`timeout`** `number | undefined`

Maximum seconds to run the detector before stopping.

---

**`controlId`** `string | undefined`

Custom control ID. Auto-generated if not provided.

---

**`onCompleted`** `(event: RelayEvent) => void | Promise<void>`

Callback invoked when detection completes.

---

## **Returns**

`Promise<`[`DetectAction`][detectaction]`>` -- An action handle with
`stop()` and `wait()` methods.

## **Example**

```typescript {13}
import { RelayClient } from '@signalwire/sdk';

const client = new RelayClient({
  project: process.env.SIGNALWIRE_PROJECT_ID!,
  token: process.env.SIGNALWIRE_API_TOKEN!,
  contexts: ['default']
});

client.onCall(async (call) => {
  await call.answer();

  // Answering machine detection
  const action = await call.detect(
    { type: 'machine', params: {} },
    { timeout: 30 }
  );
  const event = await action.wait();

  const detectResult = event.params.detect as Record<string, unknown> ?? {};
  if (detectResult.type === 'machine') {
    console.log('Answering machine detected');
    await call.hangup();
  } else {
    console.log('Human answered');
    const playAction = await call.play([{ type: 'tts', text: 'Hello! This is a call from...' }]);
    await playAction.wait();
  }
});

await client.run();
```

> Detect answering machines, fax tones, or digits on a call.