Android Dialing Screen Change

Customizing the Android Dialing Screen: A Comprehensive Guide

Explore methods to modify or replace the default Android dialing screen, including system-level changes, app development, and handling permissions.

The default Android dialing screen, often referred to as the 'InCallUI', is a core component of the Android operating system. While it serves its purpose effectively, developers and advanced users might seek to customize or even replace it for various reasons, such as adding unique features, integrating with specific services, or enhancing the user experience. This article delves into the complexities of altering the Android dialing screen, outlining the technical challenges, necessary permissions, and potential approaches.

Understanding the Android InCallUI

The InCallUI is a system-level application responsible for managing the user interface during an active phone call. It displays caller information, provides controls for muting, speakerphone, adding calls, and ending calls. Due to its critical role in communication and security, Android imposes significant restrictions on third-party applications attempting to interfere with or replace this component. Direct replacement of the entire InCallUI is generally not supported for security and stability reasons, especially in newer Android versions.

flowchart TD
    A[Incoming Call] --> B{System Call Manager}
    B --> C{Default InCallUI}
    C --> D[User Interaction]
    B --> E{Third-Party Dialer App?}
    E -- Yes --> F{Handle Call (Limited Control)}
    E -- No --> C
    F -- Requires Permissions --> G[Manifest Declarations]
    G -- Android 10+ --> H[Role.CALL_REDIRECTION]
    G -- Android 6-9 --> I[Default Dialer App]

Flowchart illustrating how Android handles incoming calls and potential third-party app interaction.

Approaches to Customization and Replacement

While a full, seamless replacement of the InCallUI is challenging, several approaches allow for varying degrees of customization or interaction with the dialing process. These methods often depend on the Android version and the specific functionality desired.

1. Becoming the Default Dialer App

This is the most common and officially supported method for third-party applications to gain significant control over call handling. By declaring your app as a replacement for the default phone app, you can manage incoming and outgoing calls, display your own UI for dialing, and even handle the in-call screen. However, even as the default dialer, direct manipulation of the system's InCallUI is restricted. Instead, you would present your own in-call screen.

2. Overlaying or Drawing Over Other Apps

For displaying custom UI elements over the existing InCallUI, apps can request the SYSTEM_ALERT_WINDOW permission. This allows an app to draw on top of other applications, including the system's call screen. This approach is often used for floating bubbles, call recording indicators, or quick access widgets. However, it doesn't replace the InCallUI; it merely overlays it. Users must explicitly grant this permission, and it can be perceived as intrusive if not used judiciously.

3. Call Screening and Redirection (Android 10+)

Android 10 introduced the Role.CALL_REDIRECTION and Role.CALL_SCREENING roles, providing more structured ways for apps to interact with calls. Apps granted these roles can intercept incoming and outgoing calls to perform actions like blocking spam, redirecting calls, or displaying custom information before the system's InCallUI appears. This is a powerful mechanism for pre-call processing but doesn't directly replace the in-call experience.

Required Permissions and Manifest Declarations

To implement any of the above approaches, your application's AndroidManifest.xml must declare specific permissions and intent filters. These declarations inform the Android system about your app's capabilities and intentions.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.mycustomdialer">

    <uses-permission android:name="android.permission.READ_CALL_LOG" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.CALL_PHONE" />
    <uses-permission android:name="android.permission.ANSWER_PHONE_CALLS" />
    <uses-permission android:name="android.permission.MANAGE_OWN_CALLS" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" /> <!-- For overlaying -->

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".MyDialerActivity">
            <intent-filter>
                <action android:name="android.intent.action.DIAL" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:scheme="tel" />
            </intent-filter>
        </activity>

        <service
            android:name=".MyCallScreeningService"
            android:permission="android.permission.BIND_CALL_SCREENING_SERVICE">
            <intent-filter>
                <action android:name="android.telecom.CallScreeningService" />
            </intent-filter>
        </service>

    </application>
</manifest>

Example AndroidManifest.xml declarations for a custom dialer and call screening service.

The android.permission.MANAGE_OWN_CALLS permission is crucial for apps that want to become the default phone app and manage calls directly. The android.telecom.CallScreeningService is used for the call screening and redirection features introduced in Android 10.

Implementing a Custom In-Call UI

If your app is set as the default dialer, you will be responsible for presenting your own in-call UI. This typically involves creating an Activity that launches when a call is established or received. This activity would then interact with the TelecomManager and InCallService APIs to manage the call state (answer, hang up, mute, etc.) and display relevant information.

1. Declare Permissions and Intent Filters

Add the necessary permissions (READ_PHONE_STATE, CALL_PHONE, MANAGE_OWN_CALLS, etc.) and intent filters for ACTION_DIAL and android.telecom.InCallService in your AndroidManifest.xml.

2. Implement InCallService

Create a class that extends android.telecom.InCallService. This service will receive callbacks for call state changes (e.g., onCallAdded, onCallRemoved).

3. Design Your In-Call Activity

Develop an Activity that serves as your custom in-call screen. This activity will be launched by your InCallService when a call is active. It should display caller information and provide controls.

4. Manage Call State

Within your InCallService and in-call Activity, use the Call object provided by the TelecomManager to interact with the call (answer, disconnect, put on hold, etc.).

5. Request Default Dialer Role

Prompt the user to set your app as the default phone app using an Intent with TelecomManager.ACTION_CHANGE_DEFAULT_DIALER.