***

id: 573c44af-7688-448e-b402-1f15d03fedde
title: Voice
sidebar-title: Overview
position: 0
keywords: 'SignalWire, Realtime SDK, Node.js, voice API, telephony, VoIP'
slug: /node/reference/voice
description: >-
Access the Voice API to make and receive phone calls programmatically.
Includes methods for call control, playback, recording, and speech detection.
max-toc-depth: 3
----------------

[voice-client-1]: /docs/server-sdk/v4/node/reference/voice/client

[voice-client]: /docs/server-sdk/v4/node/reference/voice/client#events

Access the Voice API. You can instantiate a [Voice.Client][voice-client-1] to make or receive calls.

<Info>
  Refer to [Events][voice-client] for a full list of events emitted by a [Voice.Client][voice-client-1] object.
</Info>

#### Example

The following example answers any call in the `office` topic, and immediately plays some speech.

```javascript
import { SignalWire } from "@signalwire/realtime-api";

const client = await SignalWire({ project: "ProjectID Here", token: "Token Here" })

await client.voice.listen({
  topics: ["office"],
  onCallReceived: (call) => {
    call.answer();
    call.playTTS({ text: "Hello world" });
  }
});
```

## **Classes**

<CardGroup cols={2}>
  <Card title="Call" icon="fa-solid fa-phone-volume" href="/docs/server-sdk/v4/node/reference/voice/call">
    Represents an active voice call with methods for playback, recording, speech detection, and call control.
  </Card>

  <Card title="CallCollect" icon="fa-solid fa-keyboard" href="/docs/server-sdk/v4/node/reference/voice/call-collect">
    Represents a collect operation for gathering user input via DTMF or speech during a call.
  </Card>

  <Card title="CallDetect" icon="fa-solid fa-magnifying-glass" href="/docs/server-sdk/v4/node/reference/voice/call-detect">
    Represents a detect operation for identifying answering machines, fax tones, or digits during a call.
  </Card>

  <Card title="CallPlayback" icon="fa-solid fa-play" href="/docs/server-sdk/v4/node/reference/voice/call-playback">
    Represents a playback operation for playing audio, TTS, silence, or ringtones during a call.
  </Card>

  <Card title="CallPrompt" icon="fa-solid fa-comment-dots" href="/docs/server-sdk/v4/node/reference/voice/call-prompt">
    Represents a prompt operation that combines playback with input collection during a call.
  </Card>

  <Card title="CallRecording" icon="fa-solid fa-microphone" href="/docs/server-sdk/v4/node/reference/voice/call-recording">
    Represents a recording operation for capturing audio during a call.
  </Card>

  <Card title="CallState" icon="fa-solid fa-circle-info" href="/docs/server-sdk/v4/node/reference/voice/call-state">
    Represents the state of a call with properties for tracking call progress and status.
  </Card>

  <Card title="CallTap" icon="fa-solid fa-ear-listen" href="/docs/server-sdk/v4/node/reference/voice/call-tap">
    Represents a tap operation for streaming call audio to an external destination.
  </Card>

  <Card title="Client" icon="fa-solid fa-server" href="/docs/server-sdk/v4/node/reference/voice/client">
    The main Voice client for making outbound calls and listening for inbound call events.
  </Card>

  <Card title="DeviceBuilder" icon="fa-solid fa-wrench" href="/docs/server-sdk/v4/node/reference/voice/device-builder">
    Helper class for building device configurations when dialing multiple endpoints.
  </Card>

  <Card title="Playlist" icon="fa-solid fa-list" href="/docs/server-sdk/v4/node/reference/voice/playlist">
    Helper class for building playlists of audio, TTS, silence, and ringtones for playback.
  </Card>
</CardGroup>