# Core features

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The Video SDK for Android lets users speak and hear each other in a session over VoIP using their device's microphone and speaker. Users who can't connect over VoIP can dial in by phone — see [Phone (PSTN)](/docs/video-sdk/android/pstn/).

The core controls let you connect to audio, mute and unmute, disconnect, and route between the earpiece and loudspeaker. For host-only controls, see [Host audio controls](/docs/video-sdk/android/audio/host-controls/). To let users test their microphone and speaker _before_ joining a session, see [Preview](/docs/video-sdk/android/preview/).

The `ZoomVideoSDKAudioHelper` provides the methods used to manage a user's audio. Before changing any audio state, check whether the user is already connected to audio.

```kotlin
val audioStatus = user.audioStatus
val audioType = audioStatus.audioType
val audioHelper = ZoomVideoSDK.getInstance().audioHelper
```

```java
ZoomVideoSDKAudioStatus audioStatus = user.getAudioStatus();
ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType audioType = audioStatus.getAudioType();
ZoomVideoSDKAudioHelper audioHelper = ZoomVideoSDK.getInstance().getAudioHelper();
```

`audioType` is one of the values defined on `ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType`.

| Value                             | Meaning                                                                                    |
| --------------------------------- | ------------------------------------------------------------------------------------------ |
| `ZoomVideoSDKAudioType_None`      | The user is not connected to session audio.                                                |
| `ZoomVideoSDKAudioType_VOIP`      | The user is connected over VoIP (microphone and speaker).                                  |
| `ZoomVideoSDKAudioType_TELEPHONY` | The user is connected by phone dial-in. See [Phone (PSTN)](/docs/video-sdk/android/pstn/). |

## Connect to audio

The SDK can't capture from the microphone until the user grants the `RECORD_AUDIO` runtime permission. Request it when the user takes an action that needs audio (a "Join audio" button is the conventional pattern), then call `startAudio()` on the `ZoomVideoSDKAudioHelper`.

```kotlin
private val audioPermission = registerForActivityResult(
    ActivityResultContracts.RequestPermission()
) { granted ->
    if (granted) {
        ZoomVideoSDK.getInstance().audioHelper.startAudio()
    } else {
        // Surface a message asking the user to grant the permission.
    }
}

fun onJoinAudioClicked() {
    audioPermission.launch(Manifest.permission.RECORD_AUDIO)
}
```

```java
private final ActivityResultLauncher<String> audioPermission =
    registerForActivityResult(new ActivityResultContracts.RequestPermission(), granted -> {
        if (Boolean.TRUE.equals(granted)) {
            ZoomVideoSDK.getInstance().getAudioHelper().startAudio();
        } else {
            // Surface a message asking the user to grant the permission.
        }
    });

void onJoinAudioClicked() {
    audioPermission.launch(Manifest.permission.RECORD_AUDIO);
}
```

> **Required Android permission**
>
> `RECORD_AUDIO`. See the [Android permissions overview](https://developer.android.com/guide/topics/permissions/overview) and the [Best practices](/docs/video-sdk/android/audio/best-practices/) topic for the full permission flow, including Bluetooth on Android 12+.

If the user might already be connected (for example, they joined audio earlier), check `audioType` before starting so you don't reconnect unnecessarily.

```kotlin
if (audioType == ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType.ZoomVideoSDKAudioType_None) {
    audioHelper.startAudio()
} else {
    // The user is already connected to audio.
}
```

```java
if (audioType == ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType.ZoomVideoSDKAudioType_None) {
    audioHelper.startAudio();
} else {
    // The user is already connected to audio.
}
```

## Mute and unmute a user

Mute the local user (or any user, if the local user is the host) by calling `muteAudio` with the associated `ZoomVideoSDKUser`.

```kotlin
audioHelper.muteAudio(user)
```

```java
audioHelper.muteAudio(user);
```

Unmute in the same way with `unMuteAudio`.

```kotlin
audioHelper.unMuteAudio(user)
```

```java
audioHelper.unMuteAudio(user);
```

## Disconnect from audio

To leave the audio portion of the session entirely, call `stopAudio`. Use this only when the user explicitly disconnects. To silence the user temporarily, use `muteAudio` instead.

```kotlin
if (audioType == ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType.ZoomVideoSDKAudioType_VOIP) {
    audioHelper.stopAudio()
}
```

```java
if (audioType == ZoomVideoSDKAudioStatus.ZoomVideoSDKAudioType.ZoomVideoSDKAudioType_VOIP) {
    audioHelper.stopAudio();
}
```

## Route audio between the earpiece and loudspeaker

On Android, the SDK can route VoIP audio through either the device's earpiece, default for in-call audio, or its loudspeaker. Use `setSpeaker` to toggle between them.

```kotlin
// Route audio through the loudspeaker.
audioHelper.setSpeaker(true)

// Route audio through the earpiece.
audioHelper.setSpeaker(false)
```

```java
// Route audio through the loudspeaker.
audioHelper.setSpeaker(true);

// Route audio through the earpiece.
audioHelper.setSpeaker(false);
```

Use `getSpeakerStatus` to read the current routing and `canSwitchSpeaker` to check whether the device permits switching For example, the SDK returns `false` when a wired headset or Bluetooth audio device is connected and the OS owns the route.

```kotlin
if (audioHelper.canSwitchSpeaker()) {
    val onLoudspeaker = audioHelper.speakerStatus
    audioHelper.setSpeaker(!onLoudspeaker)
}
```

```java
if (audioHelper.canSwitchSpeaker()) {
    boolean onLoudspeaker = audioHelper.getSpeakerStatus();
    audioHelper.setSpeaker(!onLoudspeaker);
}
```

When the local user is the session host, they can also mute participants, request a participant unmute, and mute everyone at once. For more information, see [Host audio controls](/docs/video-sdk/android/audio/host-controls/).