Voice-only quickstart

This Android quickstart shows you how to create a basic Voice Calling app using the Agora RTC SDK.

Understand the tech

To start a Voice Calling session, implement the following steps in your app:

• Initialize the Agora Engine: Before calling other APIs, create and initialize an Agora Engine instance.

• Join a channel: Call methods to create and join a channel.

• Send and receive audio: All users can publish streams to the channel and subscribe to audio streams published by other users in the channel.

Prerequisites

• Android Studio 4.2 or higher.

• Android SDK API Level 21 or higher.

• Two mobile devices running Android 5.0 or higher.

• A microphone

• A valid Agora account and project. Please refer to Agora account management for details.

Set up your project

This section shows you how to set up your Android project and install the Agora RTC SDK.

2. Add a layout file for your activity.

   Set up a basic layout for your activity. Refer to Create a user interface to get a bare bones sample layout.

Install the SDK

Use either of the following methods to add RTC SDK to your project.

Implement Voice Calling

This section guides you through the implementation of basic real-time audio interaction in your app.

The following figure illustrates the essential steps:

This guide includes complete sample code that demonstrates implementing basic real-time interaction. To understand the core API calls in the sample code, review the following implementation steps and use the code in your MainActivity file.

Import Agora classes

Import the relevant Agora classes and interfaces:

import io.agora.rtc2.Constants;
import io.agora.rtc2.IRtcEngineEventHandler;
import io.agora.rtc2.RtcEngine;
import io.agora.rtc2.RtcEngineConfig;
import io.agora.rtc2.ChannelMediaOptions;

import io.agora.rtc2.ChannelMediaOptions
import io.agora.rtc2.Constants
import io.agora.rtc2.IRtcEngineEventHandler
import io.agora.rtc2.RtcEngine
import io.agora.rtc2.RtcEngineConfig

Initialize the engine

For real-time communication, initialize an RtcEngine instance and set up event handlers to manage user interactions within the channel. Use RtcEngineConfig to specify the application context, App ID, and custom event handler, then call RtcEngine.create(config) to initialize the engine, enabling further channel operations. In your MainActivity file, add the following code:

// Fill in the app ID from Agora Console
private String myAppId = "<Your app ID>";
private RtcEngine mRtcEngine;

private void initializeAgoraVoiceSDK() {
  try {
    RtcEngineConfig config = new RtcEngineConfig();
    config.mContext = getBaseContext();
    config.mAppId = myAppId;
    config.mEventHandler = mRtcEventHandler;
    mRtcEngine = RtcEngine.create(config);
  } catch (Exception e) {
    throw new RuntimeException("Error initializing RTC engine: " + e.getMessage());
  }
}

// Fill in the App ID obtained from the Agora Console
private val myAppId = "<Your app ID>"
private var mRtcEngine: RtcEngine? = null

private fun initializeAgoraVoiceSDK() {
  try {
    val config = RtcEngineConfig().apply {
      mContext = baseContext
      mAppId = myAppId
      mEventHandler = mRtcEventHandler
    }
    mRtcEngine = RtcEngine.create(config)
  } catch (e: Exception) {
    throw RuntimeException("Error initializing RTC engine: ${e.message}")
  }
}

Join a channel

To join a channel, call joinChannel with the following parameters:

• Channel name: The name of the channel to join. Clients that pass the same channel name join the same channel. If a channel with the specified name does not exist, it is created when the first user joins.

• Authentication token: A dynamic key that authenticates a user when the client joins a channel. In a production environment, you obtain a token from a token server in your security infrastructure. For the purpose of this guide Generate a temporary token.

• User ID: A 32-bit signed integer that identifies a user in the channel. You can specify a unique user ID for each user yourself. If you set the user ID to 0 when joining a channel, the SDK generates a random number for the user ID and returns the value in the onJoinChannelSuccess callback.

• Channel media options: Configure ChannelMediaOptions to define publishing and subscription settings, optimize performance for your specific use-case, and set optional parameters.

For Voice Calling, set the channelProfile to CHANNEL_PROFILE_COMMUNICATION and the user role to CLIENT_ROLE_BROADCASTER.

// Fill in the channel name
private String channelName = "<Your channel name>";
// Fill in the temporary token generated from Agora Console
private String token = "<Your token>";

private void joinChannel() {
  ChannelMediaOptions options = new ChannelMediaOptions();
  options.clientRoleType = Constants.CLIENT_ROLE_BROADCASTER;
  options.channelProfile = Constants.CHANNEL_PROFILE_COMMUNICATION;
  options.publishCameraTrack = true;
  mRtcEngine.joinChannel(token, channelName, 0, options);
}

// Fill in the channel name
private val channelName = "<Your channel name>"
// Fill in the temporary token generated from Agora Console
private val token = "<Your token>"

private fun joinChannel() {
  val options = ChannelMediaOptions().apply {
    clientRoleType = Constants.CLIENT_ROLE_BROADCASTER
    channelProfile = Constants.CHANNEL_PROFILE_COMMUNICATION
    publishMicrophoneTrack = true;
  }
  mRtcEngine?.joinChannel(token, channelName, 0, options)
}

Subscribe to RTC SDK events

The RTC SDK provides an interface for subscribing to channel events. To use it, create an instance of IRtcEngineEventHandler and implement the event methods you want to handle.

private final IRtcEngineEventHandler mRtcEventHandler = new IRtcEngineEventHandler() {
  // Callback when successfully joining the channel
  @Override
  public void onJoinChannelSuccess(String channel, int uid, int elapsed) {
    super.onJoinChannelSuccess(channel, uid, elapsed);
    showToast("Joined channel " + channel);
  }
  // Callback when a remote user or host joins the current channel
  @Override
  public void onUserJoined(int uid, int elapsed) {
    super.onUserJoined(uid, elapsed);
    runOnUiThread(() -> {
      showToast("User joined: " + uid); // Show toast for user joining
    });
  }
  // Callback when a remote user or host leaves the current channel
  @Override
  public void onUserOffline(int uid, int reason) {
    super.onUserOffline(uid, reason);
    runOnUiThread(() -> {
      showToast("User offline: " + uid); // Show toast for user going offline
    });
  }
};

private val mRtcEventHandler = object : IRtcEngineEventHandler() {
  override fun onJoinChannelSuccess(channel: String?, uid: Int, elapsed: Int) {
    super.onJoinChannelSuccess(channel, uid, elapsed)
    runOnUiThread {
      showToast("Joined channel $channel")
    }
  }
  override fun onUserJoined(uid: Int, elapsed: Int) {
    runOnUiThread {
      showToast("User joined: $uid")
    }
  }
  override fun onUserOffline(uid: Int, reason: Int) {
    super.onUserOffline(uid, reason)
    runOnUiThread {
      showToast("User offline: $uid")
    }
  }
}

Handle permissions

To access the microphone on Android devices, declare the necessary permissions in the app's manifest and ensure that the user grants these permissions when the app starts.

1. Open your project's AndroidManifest.xml file and add the following permissions before <application>:

   <!--Required permissions-->
   <uses-permission android:name="android.permission.INTERNET"/>
   
   <!--Optional permissions-->
   <uses-permission android:name="android.permission.RECORD_AUDIO"/>
   <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
   <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
   <uses-permission android:name="android.permission.BLUETOOTH"/>
   <!-- For devices running Android 12 (API level 32) or higher and integrating Agora RTC SDK version v4.1.0 or lower, you also need to add the following permissions -->
   <uses-permission android:name="android.permission.BLUETOOTH_CONNECT"/>
   <!-- For Android 12 or higher, the following permissions are also required -->
   <uses-permission android:name="android.permission.READ_PHONE_STATE"/>
   <uses-permission android:name="android.permission.BLUETOOTH_SCAN"/>

2. Use the following code to handle runtime permissions in your Android app. The logic ensures that the necessary permissions are granted before starting Voice Calling. In your MainActivity file, add the following code:

   Java

   Kotlin

   private static final int PERMISSION_REQ_ID = 22;
   
     private boolean checkPermissions() {
       for (String permission : getRequiredPermissions()) {
         if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
           return false;
         }
       }
       return true;
     }
   
     private void requestPermissions() {
       ActivityCompat.requestPermissions(this, getRequiredPermissions(), PERMISSION_REQ_ID);
     }
   
     private String[] getRequiredPermissions() {
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
         return new String[]{
           Manifest.permission.RECORD_AUDIO,
           Manifest.permission.READ_PHONE_STATE,
           Manifest.permission.BLUETOOTH_CONNECT
         };
       } else {
         return new String[]{Manifest.permission.RECORD_AUDIO};
       }
     }
   
     @Override
     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
       super.onRequestPermissionsResult(requestCode, permissions, grantResults);
       if (checkPermissions()) {
         startVoiceCalling();
       }
     }

Start and close the app

When a user launches your app, start real-time interaction. When a user closes the app, stop the interaction.

1. In the onCreate callback, check whether the app has been granted the required permissions. If the permissions have not been granted, request the required permissions from the user. If permissions are granted, initialize RtcEngine and join a channel.

   Java

   Kotlin

   @Override
     protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       if (checkPermissions()) {
         startVoiceCalling();
       } else {
         requestPermissions();
       }
     }

2. When a user closes the app, or switches the app to the background, call leaveChannel to leave the current channel and release all session-related resources.

   Java

   Kotlin

   private void cleanupAgoraEngine() {
       if (mRtcEngine != null) {
         mRtcEngine.leaveChannel();
         mRtcEngine = null;
       }
     }

Complete sample code

A complete code sample demonstrating the basic process of real-time interaction is provided for your reference. To use the sample code, copy the following lines into the MainActivity file in your project. Then, replace <projectname> in package com.example.<projectname> with your project's name.

Create a user interface

Use the following code to generate a basic user interface. Paste the code into the /app/src/main/res/layout/activity_main.xml file, replacing the existing content. Sample code to create the user interface

<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:id="@+id/activity_main"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@android:color/darker_gray"
  tools:context=".MainActivity">

  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="Welcome to Agora Voice Calling." />

</RelativeLayout>

Test the sample code

Take the following steps to test the sample code:

1. In MainActivity update the values for myAppId, and token with values from Agora Console. Fill in the same channelName you used to generate the token.

2. Enable developer options on your Android test device. Turn on USB debugging, connect the Android device to your development machine through a USB cable, and check that your device appears in the Android device options.

3. In Android Studio, click Sync Project with Gradle Files to resolve project dependencies and update the configuration.

4. After synchronization is successful, click Run app. Android Studio starts compilation. After a few moments, the app is installed on your Android device.

5. Launch the App, grant the recording permission.

6. On a second Android device, repeat the previous steps to install and launch the app. Alternatively, use the Web demo to join the same channel and test the following use-cases:

   • If users on both devices join the channel as hosts, they can hear each other.
   • If one user joins as host and the other as audience, the audience can hear the host.

Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

• If a firewall is deployed in your network environment, refer to Connect with Cloud Proxy to use Agora services normally.

Next steps

After implementing the quickstart sample, read the following documents to learn more:

• To ensure communication security in a test or production environment, best practice is to obtain and use a token from an authentication server. For details, see Secure authentication with tokens.

Sample project

Agora provides open source sample projects on GitHub for your reference. Download or view the JoinChannelAudio project for a more detailed example.

API reference

• RtcEngineConfig

• create

• ChannelMediaOptions

• joinChannel

• leaveChannel

• IRtcEngineEventHandler

Frequently asked questions

• How can I listen for audience joining or leaving a channel?
• How can I solve channel-related issues?
• How can I set the log file?
• Why do apps on some Android versions fail to capture audio and video after screen locking or switching to the background?

See also

• Error codes

• Connection status management