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instead of aosp-main
to build and contribute to AOSP. For more information, see Changes to AOSP.
Technical details
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The following diagram illustrates the system components that interact with Dialer:

Figure 1. Components that interact with Dialer
-
System UI. Lower navigation facet to host the Phone button, which
registers the intent:#Intent;action=android.intent.action.MAIN;category=android.intent.category.LAUNCHER;package=com.android.car.dialer;launchFlags=0x10000000;end
intent.
This starts the user's main activity, TelecomActivity
.
-
App Launcher. Manages the entire app list. Dialer declares
TelecomActivity with android.intent.category.LAUNCHER
. Selecting the phone app from
the launcher's app list displays TelecomActivity.
-
Home widget. In AOSP reference, there is no Home widget. OEMs might want to
consider adding a Home widget for Dialer to display the state of the current connected phone (as
well as other information).
-
Notification Center
-
Heads Up Notification (HUN) is displayed for incoming calls. When the Dialer
InCallServiceImpl
receives an incoming call, Dialer posts a HUN to the
Notification center, which shows the call details, such as phone number or contact info.
Dialer also displays two action buttons, Answer and Decline. By tapping Answer button,
the call is answered and InCallServiceImpl
handles the active call to show
Dialer's in call UI and dismisses the HUN. Clicking on the HUN displays the fullscreen
InCall page with the Answer and Reject buttons.
-
Notification appears for unread missed calls. Clicking on the
notification displays the Call History page and marks missed calls as read. Tapping the
Call Back button places a call and displays the Dialer's InCall user interface.
-
Assistant. Users can ask an assistant to make a call that may display the
Dialer InCall user interface.
-
Google Maps. Calling a merchant from Google Maps sends the DIAL
intent with extras of phone numbers which will start Dialpad page for quick dialing.
-
CarInputService. Monitors the physical key of the Call and End Call
buttons on the steering wheel. Pressing the:
-
Call button from the steering wheel when there is no incoming call sends the DIAL
intent and displays the Dialpad page of Dialer.
-
Call button from the steering wheel when there is an incoming call causes the
TelecomManager to answer the call.
-
End Call button from the steering wheel when there is an incoming call, the
TelecomManager ends the call.
-
Bluetooth
-
PBAPClient. Downloads contacts from a phone and writes to the
contacts provider. For each phone connected, an account is created with the device's
Bluetooth MAC address as the account name and com.android.bluetooth.pbapsink
(@string/pbap_account_type
defined in packages/apps/Bluetooth
) as
the account type. Contacts written to the contacts provider are written with the account
information and are cleared when the phone is disconnected. PBAPClient
doesn't
interact directly with Dialer but instead writes contacts to the Contacts Provider. Dialer
reads the contacts from the Contacts Provider.
-
HfpClientConnectionService
. Manages the Bluetooth call
through HFP and reports the call to the Telecom services.
-
Telecom. The Android Telecom framework manages audio and video calls on an
Android device. Since Dialer is the default phone app, it implements the
InCallService
APIs and InCallController
will bind the Dialer's InCallService implementation to
handle calls. For more details, see
Create
a replacement phone app and
Becoming
the Default Phone App.
-
System Settings. Dialer monitors the HFP-connected device list and displays
an error message when no phones are connected to dialer through Bluetooth. In the AOSP
reference, the Connect to Bluetooth button links users to the system Bluetooth Settings
page to pair a new device or to connect to a paired device.
-
Driver Distraction Engine. This Android system service imposes UX
restrictions based on the driving state of the car. Dialer must execute all UX driving
distraction restrictions.To do so, Dialer must listen to the
CarUXRestrictionManager
and implement all policies. Dialer must:
-
Connect to the Car
library and obtain an instance of
CarUXRestrictionManager.
-
Subscribe to updates in the list of
CarUxRestrictions
and implement them as documented.
-
Of particular importance to Dialer:
-
Settings page is vehicle-optimized. User could not access the
Dialer Settings page when driving. By tapping on the Settings menu from the action bar,
a blocking screen is displayed to prevent the user from accessing Settings while
driving. If the Settings page is already displayed, the blocking screen will pop up to
stop the user interaction.
-
System settings cannot be accessed while driving. On the Error page,
when no Bluetooth devices are connected, a Connect to Bluetooth button displays the
system Bluetooth settings page. The UXR of this button is fully restricted.
While driving, clicking on this button displays an error message to inform the
user to park the car first and then perform the action.
-
User cannot start the add-to-favorite flow while driving. The Add a
Favorite button is disabled.
User flows
Dialer Main
The different pages for Dialer are provided below.

Figure 2. Main Dialer page
Call handling
The call handing process flow is presented below:

Figure 3. Call handling
Notifications
The different notifications pages are displayed below:

Figure 4. Notifications
InCall status
The InCall page flow is shown below:

Figure 5. InCall page
Search
The Search displays are:

Figure 6. Search
Settings
The Settings options are:

Figure 7. Settings
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-03-13 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-13 UTC."],[],[],null,["# Technical details\n\nThe following diagram illustrates the system components that interact with Dialer:\n\n**Figure 1.** Components that interact with Dialer\n\n- **System UI.** Lower navigation facet to host the Phone button, which\n registers the `intent:#Intent;action=android.intent.action.MAIN;category=android.intent.category.LAUNCHER;package=com.android.car.dialer;launchFlags=0x10000000;end` intent.\n This starts the user's main activity, `TelecomActivity`.\n\n- **App Launcher.** Manages the entire app list. Dialer declares\n TelecomActivity with `android.intent.category.LAUNCHER`. Selecting the phone app from\n the launcher's app list displays TelecomActivity.\n\n- **Home widget.** In AOSP reference, there is no Home widget. OEMs might want to\n consider adding a Home widget for Dialer to display the state of the current connected phone (as\n well as other information).\n\n- **Notification Center**\n\n - **Heads Up Notification (HUN) is displayed for incoming calls.** When the Dialer\n `InCallServiceImpl` receives an incoming call, Dialer posts a HUN to the\n Notification center, which shows the call details, such as phone number or contact info.\n Dialer also displays two action buttons, Answer and Decline. By tapping Answer button,\n the call is answered and `InCallServiceImpl` handles the active call to show\n Dialer's in call UI and dismisses the HUN. Clicking on the HUN displays the fullscreen\n InCall page with the Answer and Reject buttons.\n\n - **Notification appears for unread missed calls.** Clicking on the\n notification displays the Call History page and marks missed calls as read. Tapping the\n Call Back button places a call and displays the Dialer's InCall user interface.\n\n- **Assistant.** Users can ask an assistant to make a call that may display the\n Dialer InCall user interface.\n\n- **Google Maps.**Calling a merchant from Google Maps sends the DIAL\n intent with extras of phone numbers which will start Dialpad page for quick dialing.\n\n- **CarInputService.**Monitors the physical key of the Call and End Call\n buttons on the steering wheel. Pressing the:\n\n - Call button from the steering wheel when there is no incoming call sends the DIAL\n intent and displays the Dialpad page of Dialer.\n\n - Call button from the steering wheel when there is an incoming call causes the\n TelecomManager to answer the call.\n\n - End Call button from the steering wheel when there is an incoming call, the\n TelecomManager ends the call.\n\n- **Bluetooth**\n\n - **PBAPClient.** Downloads contacts from a phone and writes to the\n contacts provider. For each phone connected, an account is created with the device's\n Bluetooth MAC address as the account name and `com.android.bluetooth.pbapsink`\n (`@string/pbap_account_type` defined in `packages/apps/Bluetooth`) as\n the account type. Contacts written to the contacts provider are written with the account\n information and are cleared when the phone is disconnected. `PBAPClient` doesn't\n interact directly with Dialer but instead writes contacts to the Contacts Provider. Dialer\n reads the contacts from the Contacts Provider.\n\n - **`HfpClientConnectionService`.** Manages the Bluetooth call\n through HFP and reports the call to the Telecom services.\n\n- **Telecom.** The Android Telecom framework manages audio and video calls on an\n Android device. Since Dialer is the default phone app, it implements the\n [InCallService](https://developer.android.com/reference/android/telecom/InCallService.html)\n APIs and `InCallController` will bind the Dialer's InCallService implementation to\n handle calls. For more details, see\n [Create\n a replacement phone app](https://developer.android.com/guide/topics/connectivity/telecom#replacePhoneApp) and\n [Becoming\n the Default Phone App](https://developer.android.com/reference/android/telecom/InCallService.html#becoming-the-default-phone-app).\n\n- **System Settings.** Dialer monitors the HFP-connected device list and displays\n an error message when no phones are connected to dialer through Bluetooth. In the AOSP\n reference, the Connect to Bluetooth button links users to the system Bluetooth Settings\n page to pair a new device or to connect to a paired device.\n\n- **Driver Distraction Engine.** This Android system service imposes UX\n restrictions based on the driving state of the car. Dialer must execute all UX driving\n distraction restrictions.To do so, Dialer must listen to the\n [CarUXRestrictionManager](https://developer.android.com/reference/android/car/drivingstate/CarUxRestrictionsManager)\n and implement all policies. Dialer must:\n\n - Connect to the [Car](https://developer.android.com/reference/android/car/Car)\n library and obtain an instance of\n [CarUXRestrictionManager](https://developer.android.com/reference/android/car/drivingstate/CarUxRestrictionsManager).\n\n - Subscribe to updates in the list of\n [CarUxRestrictions](https://developer.android.com/reference/android/car/drivingstate/CarUxRestrictions)\n and implement them as documented.\n\n - Of particular importance to Dialer:\n\n - **Settings page is vehicle-optimized.** User could not access the\n Dialer Settings page when driving. By tapping on the Settings menu from the action bar,\n a blocking screen is displayed to prevent the user from accessing Settings while\n driving. If the Settings page is already displayed, the blocking screen will pop up to\n stop the user interaction.\n\n - **System settings cannot be accessed while driving.** On the Error page,\n when no Bluetooth devices are connected, a Connect to Bluetooth button displays the\n system Bluetooth settings page. The UXR of this button is fully restricted.\n While driving, clicking on this button displays an error message to inform the\n user to park the car first and then perform the action.\n\n - **User cannot start the add-to-favorite flow while driving.** The Add a\n Favorite button is disabled.\n\nUser flows\n----------\n\n### Dialer Main\n\nThe different pages for Dialer are provided below.\n\n**Figure 2.** Main Dialer page\n\n### Call handling\n\nThe call handing process flow is presented below:\n\n**Figure 3.** Call handling\n\n### Notifications\n\nThe different notifications pages are displayed below:\n\n**Figure 4.** Notifications\n\n### InCall status\n\nThe InCall page flow is shown below:\n\n**Figure 5.** InCall page\n\n### Search\n\nThe Search displays are:\n\n**Figure 6.** Search\n\n### Settings\n\nThe Settings options are:\n\n**Figure 7.** Settings"]]