Call Session - CometChat Docs

Quick Reference for AI Agents & Developers

// Generate token
val sessionId = "SESSION_ID"
val userAuthToken = CometChat.getUserAuthToken()
CometChatCalls.generateToken(sessionId, userAuthToken, object : CometChatCalls.CallbackListener<GenerateToken>() {
    override fun onSuccess(token: GenerateToken) { /* Start session */ }
    override fun onError(e: CometChatException) { }
})

// Start session
val callSettings = CometChatCalls.CallSettingsBuilder(context, videoContainer)
    .setDefaultLayoutEnable(true)
    .setIsAudioOnly(false)
    .build()
CometChatCalls.startSession(token, callSettings, callback)

// End session
CometChatCalls.endSession()

Available via: SDK | UI Kits

Overview

This section demonstrates how to start a call session in an Android application. Previously known as Direct Calling. Before you begin, we strongly recommend you read the calling setup guide.

If you want to implement a complete calling experience with ringing functionality (incoming/outgoing call UI), follow the Ringing guide first. Once the call is accepted, return here to start the call session.

Generate Call Token

A call token is required for secure access to a call session. Each token is unique to a specific session and user combination, ensuring that only authorized users can join the call. You can generate the token just before starting the call, or generate and store it ahead of time based on your use case. Use the generateToken() method to create a call token:

Java
Kotlin

String sessionId = "" //Random or available in call obecjt in case of default calling
String userAuthToken = CometChat.getUserAuthToken() //Logged in user auth token

CometChatCalls.generateToken(sessionId, userAuthToken, new CometChatCalls.CallbackListener<GenerateToken>() {
    @Override
    public void onSuccess(GenerateToken generateToken) {

    }

    @Override
    public void onError(com.cometchat.pro.rtc.exceptions.CometChatException e) {

    }
});

val sessionId = "" //Random or available in call obecjt in case of default calling
val userAuthToken = CometChat.getUserAuthToken() //Logged in user auth token

CometChatCalls.generateToken(
    sessionId,
    userAuthToken,
    object : CometChatCalls.CallbackListener<GenerateToken>() {
        override fun onSuccess(generateToken: GenerateToken) {
            
        }

        override fun onError(e: CometChatException) {
          
        }
    }
)

Parameter	Description
`sessionId`	The unique random session ID. In case you are using the ringing flow, the session ID is available in the `Call` object.
`userAuthToken`	The user auth token is the logged-in user auth token which you can get by calling CometChat Chat SDK method `CometChat.getUserAuthToken()`

Start Call Session

Use the startSession() method to join a call session. This method requires a call token (generated in the previous step) and a CallSettings object that configures the call UI and behavior. The CallSettings class configures the call UI and behavior. Use CallSettingsBuilder to create a CallSettings instance with the following required parameters:

Parameter	Description
`activityContext`	The activity context where the call UI will be displayed
`videoContainer`	A `RelativeLayout` where the calling UI will be rendered
`callToken`	The `GenerateToken` object received from `generateToken()` onSuccess

Java
Kotlin

RelativeLayout videoContainer = findViewById(R.id.video_container);
Context activityContext = this;
GenerateToken callToken; // Received from generateToken() onSuccess

CallSettings callSettings = new CometChatCalls.CallSettingsBuilder(activityContext, videoContainer)
    .setDefaultLayoutEnable(true)
    .setIsAudioOnly(false)
    .build();

CometChatCalls.startSession(callToken, callSettings, new CometChatCalls.CallbackListener<String>() {
    @Override
    public void onSuccess(String s) {
        // Call session started successfully
    }

    @Override
    public void onError(CometChatException e) {
        // Handle error
    }
});

val videoContainer: RelativeLayout = findViewById(R.id.video_container)
val activityContext: Context = this
val callToken: GenerateToken // Received from generateToken() onSuccess

val callSettings = CometChatCalls.CallSettingsBuilder(activityContext, videoContainer)
    .setDefaultLayoutEnable(true)
    .setIsAudioOnly(false)
    .build()

CometChatCalls.startSession(callToken, callSettings, object : CometChatCalls.CallbackListener<String> {
    override fun onSuccess(s: String) {
        // Call session started successfully
    }

    override fun onError(e: CometChatException) {
        // Handle error
    }
})

Call Settings

Configure the call experience using the following CallSettingsBuilder methods:

Method	Description
`setDefaultLayoutEnable(boolean)`	Enables or disables the default call UI layout with built-in controls. `true` shows the default layout with end call, mute, video toggle buttons. `false` hides the button layout. Default: `true`
`setIsAudioOnly(boolean)`	Sets whether the call is audio-only or audio-video. `true` for audio-only, `false` for audio-video. Default: `false`
`setEventListener(CometChatCallsEventsListener)`	Sets the listener to receive call events. See Call Listeners for available callbacks.
`setMode(String)`	Sets the call UI layout mode. Available: `MODE_DEFAULT` (grid), `MODE_SPOTLIGHT` (active speaker), `MODE_SINGLE` (one participant). Default: `MODE_DEFAULT`
`setAvatarMode(String)`	Sets how avatars are displayed when video is off. Available: `AVATAR_MODE_CIRCLE`, `AVATAR_MODE_SQUARE`, `AVATAR_MODE_FULLSCREEN`. Default: `AVATAR_MODE_CIRCLE`
`setDefaultAudioMode(String)`	Sets the initial audio output device. Available: `AUDIO_MODE_SPEAKER`, `AUDIO_MODE_EARPIECE`, `AUDIO_MODE_BLUETOOTH`, `AUDIO_MODE_HEADPHONES`
`startWithAudioMuted(boolean)`	Starts the call with the microphone muted. Default: `false`
`startWithVideoMuted(boolean)`	Starts the call with the camera turned off. Default: `false`
`showEndCallButton(boolean)`	Shows or hides the end call button in the default layout. Default: `true`
`showSwitchCameraButton(boolean)`	Shows or hides the switch camera button (front/back). Default: `true`
`showMuteAudioButton(boolean)`	Shows or hides the mute audio button. Default: `true`
`showPauseVideoButton(boolean)`	Shows or hides the pause video button. Default: `true`
`showAudioModeButton(boolean)`	Shows or hides the audio mode selection button. Default: `true`
`showSwitchToVideoCallButton(boolean)`	Shows or hides the button to upgrade an audio call to video. Default: `true`
`showRecordingButton(boolean)`	Shows or hides the recording button. Default: `false`
`autoRecordOnCallStart(boolean)`	Automatically starts recording when the call begins. Default: `false`
`enableVideoTileClick(boolean)`	Enables or disables click interactions on video tiles in Spotlight mode. Default: `true`
`enableVideoTileDrag(boolean)`	Enables or disables drag functionality for video tiles in Spotlight mode. Default: `true`
`setMainVideoContainerSetting(MainVideoContainerSetting)`	Customizes the main video container. See Video View Customization.
`setIdleTimeoutPeriod(int)`	Sets idle timeout in seconds. Warning appears 60 seconds before auto-termination. Default: `180` seconds. v4.1.0+

Call Listeners

The CometChatCallsEventsListener interface provides real-time callbacks for call session events, including participant changes, call state updates, and error conditions. Register this listener in any activity or fragment where you need to respond to call events. Each listener requires a unique listenerId string. This ID is used to:

Prevent duplicate registrations — Re-registering with the same ID replaces the existing listener
Enable targeted removal — Remove specific listeners without affecting others

Java
Kotlin

private String listenerId = "UNIQUE_LISTENER_ID";

// Register listener (e.g., in onCreate or onResume)
CometChatCalls.addCallsEventListeners(listenerId, new CometChatCallsEventsListener() {
    @Override
    public void onCallEnded() {

    }

    @Override
    public void onSessionTimeout() {

    }

    @Override
    public void onCallEndButtonPressed() {

    }

    @Override
    public void onUserJoined(RTCUser user) {

    }

    @Override
    public void onUserLeft(RTCUser user) {

    }

    @Override
    public void onUserListChanged(ArrayList<RTCUser> users) {

    }

    @Override
    public void onAudioModeChanged(ArrayList<AudioMode> devices) {

    }

    @Override
    public void onCallSwitchedToVideo(CallSwitchRequestInfo info) {

    }

    @Override
    public void onUserMuted(RTCMutedUser muteObj) {

    }

    @Override
    public void onRecordingToggled(RTCRecordingInfo info) {

    }

    @Override
    public void onError(CometChatException ce) {

    }
});

// Unregister listener (e.g., in onDestroy or onPause)
CometChatCalls.removeCallsEventListeners(listenerId);

val listenerId = "UNIQUE_LISTENER_ID"

// Register listener (e.g., in onCreate or onResume)
CometChatCalls.addCallsEventListeners(listenerId, object: CometChatCallsEventsListener {
    override fun onCallEnded() {

    }

    override fun onSessionTimeout() {

    }

    override fun onCallEndButtonPressed() {

    }

    override fun onUserJoined(user: RTCUser) {

    }

    override fun onUserLeft(user: RTCUser) {

    }

    override fun onUserListChanged(users: ArrayList<RTCUser>) {

    }

    override fun onAudioModeChanged(devices: ArrayList<AudioMode?>?) {

    }

    override fun onCallSwitchedToVideo(info: CallSwitchRequestInfo) {

    }

    override fun onUserMuted(muteObj: RTCMutedUser) {

    }

    override fun onRecordingToggled(info: RTCRecordingInfo) {

    }

    override fun onError(ce: CometChatException?) {

    }
})

Always remove call event listeners when they’re no longer needed (e.g., in onDestroy() or when navigating away). Failing to remove listeners can cause memory leaks and duplicate event handling.

Events

Event	Description
`onCallEnded()`	Invoked when the call session terminates for a 1:1 call. Both participants receive this callback. Only fires for calls with exactly 2 participants.
`onSessionTimeout()`	Invoked when the call is auto-terminated due to inactivity (default: 180 seconds). Warning appears 60 seconds before. v4.1.0+
`onCallEndButtonPressed()`	Invoked when the local user taps the end call button. For ringing flow, call `CometChat.endCall()`. For standalone, call `CometChatCalls.endSession()`.
`onUserJoined(user: RTCUser)`	Invoked when a remote participant joins. The `user` contains UID, name, and avatar.
`onUserLeft(user: RTCUser)`	Invoked when a remote participant leaves the call session.
`onUserListChanged(users: ArrayList<RTCUser>)`	Invoked whenever the participant list changes (join or leave events).
`onAudioModeChanged(devices: ArrayList<AudioMode>)`	Invoked when available audio devices change (e.g., Bluetooth connected).
`onCallSwitchedToVideo(info: CallSwitchRequestInfo)`	Invoked when an audio call is upgraded to a video call.
`onUserMuted(muteObj: RTCMutedUser)`	Invoked when a participant’s mute state changes.
`onRecordingToggled(info: RTCRecordingInfo)`	Invoked when call recording starts or stops.
`onError(e: CometChatException)`	Invoked when an error occurs during the call session.

End Call Session

Ending a call session properly is essential to release media resources (camera, microphone, network connections) and update call state across all participants. The termination process differs based on whether you’re using the Ringing flow or Session Only flow.

Ringing Flow

When using the Ringing flow, you must coordinate between the CometChat Chat SDK and the Calls SDK to properly terminate the call and notify all participants.

The Ringing flow requires calling methods from both the Chat SDK (CometChat.endCall()) and the Calls SDK (CometChatCalls.endSession()) to ensure proper call termination and participant notification.

User who initiates the end call: When the user presses the end call button in the UI, the onCallEndButtonPressed() callback is triggered. You must call CometChat.endCall() inside this callback to properly terminate the call and notify other participants. This triggers the onCallEnded() callback for the remote participant.

Java
Kotlin

@Override
public void onCallEndButtonPressed() {
    CometChat.endCall(sessionId, new CometChat.CallbackListener<Call>() {
        @Override
        public void onSuccess(Call call) {
            // Call ended successfully, close the calling screen
        }

        @Override
        public void onError(CometChatException e) {
            Log.e(TAG, "Error ending call: " + e.getMessage());
        }
    });
}

override fun onCallEndButtonPressed() {
    CometChat.endCall(sessionId, object : CallbackListener<Call?>() {
        override fun onSuccess(call: Call?) {
            // Call ended successfully, close the calling screen
        }

        override fun onError(e: CometChatException) {
            Log.e(TAG, "Error ending call: ${e.message}")
        }
    })
}

Remote participant (receives the onCallEnded() callback): Call CometChat.clearActiveCall() to clear the local call state, then call CometChatCalls.endSession() to release media resources.

Java
Kotlin

// In onCallEnded() callback
CometChat.clearActiveCall();
CometChatCalls.endSession();
// Close the calling screen

// In onCallEnded() callback
CometChat.clearActiveCall()
CometChatCalls.endSession()
// Close the calling screen

Session Only Flow

When using the Session Only flow (direct call without ringing), you only need to call the Calls SDK method to end the session. There’s no need to notify the Chat SDK since no call signaling was involved. Call CometChatCalls.endSession() in the onCallEndButtonPressed() callback to release all media resources and disconnect from the call session.

Java
Kotlin

// In onCallEndButtonPressed() callback
CometChatCalls.endSession();
// Close the calling screen

// In onCallEndButtonPressed() callback
CometChatCalls.endSession()
// Close the calling screen

Methods

These methods are available for performing custom actions during an active call session. Use them to build custom UI controls or implement specific behaviors based on your use case.

These methods can only be called when a call session is active.

Switch Camera

Toggles between the front and rear camera during a video call. Useful for allowing users to switch their camera view without leaving the call.

Java
Kotlin

CometChatCalls.switchCamera();

CometChatCalls.switchCamera()

Mute Audio

Controls the local audio stream transmission. When muted, other participants cannot hear the local user.

true — Mutes the microphone, stops transmitting audio
false — Unmutes the microphone, resumes audio transmission

Java
Kotlin

CometChatCalls.muteAudio(true);

CometChatCalls.muteAudio(true)

Pause Video

Controls the local video stream transmission. When paused, other participants see a frozen frame or avatar instead of live video.

true — Pauses the camera, stops transmitting video
false — Resumes the camera, continues video transmission

Java
Kotlin

CometChatCalls.pauseVideo(true);

CometChatCalls.pauseVideo(true)

Set Audio Mode

Routes the audio output to a specific device. Use this to let users choose between speaker, earpiece, or connected audio devices. Available modes:

CometChatCallsConstants.AUDIO_MODE_SPEAKER — Device speaker (loudspeaker)
CometChatCallsConstants.AUDIO_MODE_EARPIECE — Phone earpiece
CometChatCallsConstants.AUDIO_MODE_BLUETOOTH — Connected Bluetooth device
CometChatCallsConstants.AUDIO_MODE_HEADPHONES — Wired headphones

Java
Kotlin

String audioMode = CometChatCallsConstants.AUDIO_MODE_EARPIECE;
CometChatCalls.setAudioMode(audioMode);

val audioMode = CometChatCallsConstants.AUDIO_MODE_EARPIECE
CometChatCalls.setAudioMode(audioMode)

Enter PIP Mode

Enters Picture-in-Picture mode, rendering the call view in a small floating window. This allows users to multitask while staying on the call. Ensure your app has PIP support enabled in the manifest.

Java
Kotlin

CometChatCalls.enterPIPMode();

CometChatCalls.enterPIPMode()

Exit PIP Mode

Exits Picture-in-Picture mode and returns the call view to its original full-screen or embedded layout.

Java
Kotlin

CometChatCalls.exitPIPMode();

CometChatCalls.exitPIPMode()

Switch To Video Call

Upgrades an ongoing audio call to a video call. This enables the camera and starts transmitting video to other participants. The remote participant receives the onCallSwitchedToVideo() callback.

Java
Kotlin

CometChatCalls.switchToVideoCall();

CometChatCalls.switchToVideoCall()

Start Recording

Starts recording the call session. The recording is saved to the CometChat server and can be accessed later. All participants receive the onRecordingToggled() callback when recording starts.

Java
Kotlin

CometChatCalls.startRecording();

CometChatCalls.startRecording()

Stop Recording

Stops an ongoing call recording. All participants receive the onRecordingToggled() callback when recording stops.

Java
Kotlin

CometChatCalls.stopRecording();

CometChatCalls.stopRecording()

End Call

Terminates the current call session and releases all media resources (camera, microphone, network connections). After calling this method, the call view should be closed.

Java
Kotlin

CometChatCalls.endSession();

CometChatCalls.endSession()

Best Practices

Always Remove Call Event Listeners

Remove call event listeners in onDestroy() or onPause() to prevent memory leaks. Use unique listener IDs to manage multiple listeners across different activities or fragments.

Validate Video Container

Ensure the RelativeLayout for the video container exists in your XML layout before calling startSession(). The container must be visible and properly sized to display video streams.

Handle Token Generation Errors

Always implement error handling for generateToken(). Token generation can fail due to network issues or invalid session IDs. Inform users and provide retry options.

Configure Call Settings Appropriately

Set setIsAudioOnly(true) for audio-only calls to save bandwidth and improve performance. Use startWithAudioMuted() or startWithVideoMuted() when appropriate for user privacy.

End Sessions Properly

Always call endSession() when leaving the call screen to release camera, microphone, and network resources. For ringing flow, call CometChat.endCall() first to notify participants.

Troubleshooting

Token Generation Failed

Symptom: generateToken() fails with “Invalid session ID” or “Unauthorized” error.Cause: Invalid session ID or user not logged in.Solution: Verify the session ID is correct (from Call object in ringing flow or generated randomly for standalone). Ensure CometChat.login() was called successfully and getUserAuthToken() returns a valid token.

Black Screen During Call

Symptom: Call starts but shows a black screen instead of video.Cause: Video container not properly configured or camera permissions denied.Solution: Verify the RelativeLayout exists in your XML and is visible. Check that camera permissions are granted in AndroidManifest.xml and at runtime. Ensure setIsAudioOnly(false) is set for video calls.

Call Session Won't Start

Symptom: startSession() fails or doesn’t trigger any callbacks.Cause: Invalid call token or missing calling setup.Solution: Ensure you’ve completed the Calling Setup including adding the Calls SDK dependency. Verify the GenerateToken object is valid and not expired. Check that the activity context is valid.

Audio Not Working

Symptom: Video works but no audio is transmitted or received.Cause: Microphone permissions denied or audio muted.Solution: Check that microphone permissions are granted. Verify startWithAudioMuted(false) is set. Test audio output device using setAudioMode() to switch between speaker and earpiece.

Next Steps

Ringing

Implement complete calling workflow with incoming/outgoing call UI

Call Logs

Retrieve and display call history for users and groups

Recording

Record calls and access recordings from the Dashboard

Video View Customization

Customize video tile layouts and appearance

​Overview

​Generate Call Token

​Start Call Session

​Call Settings

​Call Listeners

​Events

​End Call Session

​Ringing Flow

​Session Only Flow

​Methods

​Switch Camera

​Mute Audio

​Pause Video

​Set Audio Mode

​Enter PIP Mode

​Enter PIP Mode

​Exit PIP Mode

​Switch To Video Call

​Start Recording

​Stop Recording

​End Call

​Best Practices

​Troubleshooting

​Next Steps

Ringing

Call Logs

Recording

Video View Customization

Overview

Generate Call Token

Start Call Session

Call Settings

Call Listeners

Events

End Call Session

Ringing Flow

Session Only Flow

Methods

Switch Camera

Mute Audio

Pause Video

Set Audio Mode

Enter PIP Mode

Enter PIP Mode

Exit PIP Mode

Switch To Video Call

Start Recording

Stop Recording

End Call

Best Practices

Troubleshooting

Next Steps