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--- title: Enable closed captions for Android titleSuffix: An Azure Communication Services article description: This article describes how to add closed captions to your existing Android calling app using Azure Communication Services. author: Kunaal services: azure-communication-services ms.subservice: calling ms.author: valindrae ms.date: 06/28/2025 ms.topic: include ms.service: azure-communication-services --- ## Prerequisites - Azure account with an active subscription, for details see [Create an account for free](https://azure.microsoft.com/pricing/purchase-options/azure-account?cid=msft_learn). - Azure Communication Services resource. See [Create an Azure Communication Services resource](../../../../quickstarts/create-communication-resource.md?tabs=windows&pivots=platform-azp). Save the connection string for this resource. - An app with voice and video calling, refer to our [Voice](../../../../quickstarts/voice-video-calling/getting-started-with-calling.md) and [Video](../../../../quickstarts/voice-video-calling/get-started-with-video-calling.md) articles. > [!NOTE] > You need to have a voice calling app using Azure Communication Services calling SDKs to access the closed captions feature described here. ## Models | Name | Description | | --- | --- | | CaptionsCallFeature | API for captions call feature | | CommunicationCaptions | API for communication captions | | StartCaptionOptions | Closed caption options like spoken language | | CommunicationCaptionsListener | Listener for CommunicationCaptions addOnCaptionsReceivedListener | | CommunicationCaptionsReceivedEvent | Data object received for each CommunicationCaptionsListener event | ## Get closed captions feature You need to get and cast the captions object to use captions specific features. ``` java CaptionsCallFeature captionsCallFeature = call.feature(Features.CAPTIONS); captionsCallFeature.getCaptions().whenComplete( ((captions, throwable) -> { if (throwable == null) { CallCaptions callCaptions = captions; if (captions.getCaptionsType() == CaptionsType.COMMUNICATION_CAPTIONS) { // communication captions CommunicationCaptions communicationCaptions = (CommunicationCaptions) captions; } } else { // get captions failed // throwable is the exception/cause } })); ``` ## Subscribe to listeners ### Add a listener to receive captions enabled/disabled status ``` java public void addOnIsCaptionsEnabledChangedListener() { communicationCaptions.addOnCaptionsEnabledChangedListener( (PropertyChangedEvent args) -> { if(communicationCaptions.isEnabled()) { // captions enabled } }); } ``` ### Add a listener to receive captions type changed This event triggers when the caption type changes from `CommunicationCaptions` to `TeamsCaptions` upon inviting Microsoft 365 users to Azure Communication Services-only calls. ``` java public void addOnIsCaptionsTypeChangedListener() { captionsCallFeature.addOnActiveCaptionsTypeChangedListener( (PropertyChangedEvent args) -> { if(communicationCaptions.isEnabled()) { // captionsCallFeature.getCaptions(); } }); } ``` ### Add listener for captions data received ``` java CommunicationCaptionsListener captionsListener = (CommunicationCaptionsReceivedEvent args) -> { // Information about the speaker. // CallerInfo participantInfo = args.getSpeaker(); // The original text with no transcribed. // args.getSpokenText(); // language identifier for the speaker. // args.getSpokenLanguage(); // Timestamp denoting the time when the corresponding speech was made. // args.getTimestamp(); // CaptionsResultType is Partial if text contains partially spoken sentence. // It is set to Final once the sentence has been completely transcribed. // args.getResultType() == CaptionsResultType.FINAL; }; public void addOnCaptionsReceivedListener() { communicationCaptions.addOnCaptionsReceivedListener(captionsListener); } ``` ### Add a listener to receive active spoken language changed status ``` java public void addOnActiveSpokenLanguageChangedListener() { communicationCaptions.addOnActiveSpokenLanguageChangedListener( (PropertyChangedEvent args) -> { // communicationCaptions.getActiveSpokenLanguage() }); } ``` ## Start captions Once you set up all your listeners, you can start adding captions. ``` java public void startCaptions() { StartCaptionsOptions startCaptionsOptions = new StartCaptionsOptions(); startCaptionsOptions.setSpokenLanguage("en-us"); communicationCaptions.startCaptions(startCaptionsOptions).whenComplete((result, error) -> { if (error != null) { } }); } ``` ## Stop captions ``` java public void stopCaptions() { communicationCaptions.stopCaptions().whenComplete((result, error) -> { if (error != null) { } }); } ``` ## Remove caption received listener ``` java public void removeOnCaptionsReceivedListener() { communicationCaptions.removeOnCaptionsReceivedListener(captionsListener); } ``` ## Spoken language support ### Get list of supported spoken languages Get a list of supported spoken languages that your users can select from when enabling closed captions. ``` java // bcp 47 formatted language code communicationCaptions.getSupportedSpokenLanguages(); ``` ### Set spoken language When the user selects the spoken language, your app can set the spoken language that it expects captions to be generated from. ``` java public void setSpokenLanguage() { communicationCaptions.setSpokenLanguage("en-us").whenComplete((result, error) -> { if (error != null) { } }); } ``` ## Clean up See [cleaning up resources](../../../create-communication-resource.md?pivots=platform-azp&tabs=windows#clean-up-resources).