For reliable mobile-call state, use Android’s telephony callback; for a device-wide indication that a call is active, use Telecom’s aggregate call-state route. A proximity sensor detects nearby objects, and audio focus manages competing audio—not either one a definitive way to detect a call. If your app owns the VoIP call, integrate it with Android Telecom.
Choose the method by the call you need to detect
“Is there a call?” can mean a change on one mobile subscription, any call the system recognizes, or a call made by your own VoIP app. Those are different scopes, so no single signal answers all three questions.
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| Method | What it observes | Best fit | Key limitation |
|---|---|---|---|
TelephonyCallback.CallStateListener |
Mobile telephony state for the registered subscription: idle, ringing, or off-hook | Responding to cellular call-state changes | API 31+ and READ_PHONE_STATE required; subscription-specific. Android notes callback state may differ from a contemporaneous getCallState() query. Android API reference |
| Aggregate Telecom call state | Whether the device is considered in a call across call services | A coarse, device-wide in-call check | A boolean-style aggregate, not a detailed per-subscription lifecycle. Android TelephonyManager reference |
| Proximity sensor | Distance or near/far status of an object | Adjusting screen or interaction behavior when the handset is near a face | Does not identify a call; availability and output vary by device. Android position sensors guide |
| Audio focus | Which app’s audio use has focus and changes in that focus | Pausing, ducking, or coordinating app playback | Not a general call-state event; non-call audio and platform policy can affect it. API 35-targeting apps face restrictions on requesting focus. Android audio focus guide |
| Telecom/Core-Telecom integration | The lifecycle and audio behavior of the app’s own managed VoIP calls | VoIP apps that need operating-system call integration | Represents your app’s calls; it does not reveal another app’s private call lifecycle. Android Telecom Framework guidance |
Detect cellular call-state changes
On Android 12 (API 31) and later, register a TelephonyCallback.CallStateListener with the TelephonyManager for the subscription you care about. The app needs the READ_PHONE_STATE permission. The callback reports CALL_STATE_IDLE, CALL_STATE_RINGING, and CALL_STATE_OFFHOOK. See the listener reference for the API contract.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteWhere a device has multiple subscriptions, use a subscription-specific telephony manager when the app needs to monitor a particular line. Register and interpret the listener in the context of that subscription rather than treating it as a device-wide call feed.
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Do not require a callback and a separate getCallState() query to agree at the exact same instant. Android documents that the value observed in the callback can differ from a query made inside it. Also note that TelephonyManager.getCallState() is deprecated; consult the TelephonyManager documentation and select an alternative according to the scope required.
Check whether Telecom considers the device in a call
Use the aggregate Telecom route, such as TelecomManager.isInCall(), when the question is broadly whether the device is in a call. It answers a different question from a listener tied to one mobile subscription: it is an aggregate indication, not a per-line transition history.
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The deprecated TelephonyManager.getCallState() documentation describes a scope that can include calls from other ConnectionService implementations. That distinction matters when an app needs a broad system-level check rather than the state of its own subscription. Check the current Android reference for the API details.
Use proximity for interaction, not call detection
Sensor.TYPE_PROXIMITY reports how near an object is; it does not report whether a call is ringing, connected, or finished. The nearby object could be a face, a pocket, a case, or something else. Proximity is useful for behavior such as turning off the display when a handset is held to a face, but it is only a contextual sensor signal.
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Sensor implementations differ: many report distance in centimeters, while some provide only a near/far result. Check whether the device has a proximity sensor and inspect its maximum range instead of assuming a universal threshold. Android describes these variations in its position sensors guide.
Treat audio focus as audio coordination
Audio focus lets apps coordinate playback—for example, pausing or lowering volume when another audio use takes priority. A focus change may coincide with call-related audio behavior, but it is not a documented, authoritative callback for general phone-call start or end. Other apps and system audio policy can also change focus.
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There is a target-SDK constraint to account for: apps targeting API 35 or higher can request audio focus only when they are the top app or are running a foreground service. Focus behavior and audio policy also vary with Android versions; consult the AudioManager reference and audio focus guide for implementation details.
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Represent your VoIP calls through Telecom
If the app makes or receives VoIP calls, use Android Telecom or Core-Telecom to integrate the app’s own call lifecycle and audio handling with the operating system. This is the appropriate path for coordinating concurrent calls and audio-device changes; raw audio focus or proximity readings do not substitute for representing the call to Telecom.
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Android’s Telecom Framework guidance advises: “Don’t directly use Audio or Bluetooth APIs to manage audio focus and routing; instead, rely on the Telecom framework to handle concurrent call scenarios and audio device changes.” Telecom integration concerns calls owned by your app, not access to another app’s private call state.
Quick Recap
Practical selection checklist
- One cellular subscription: use
TelephonyCallback.CallStateListeneron API 31+ and requestREAD_PHONE_STATE. - Broad device in-call status: use Telecom’s aggregate in-call indication rather than interpreting proximity or focus.
- Your app’s VoIP lifecycle: integrate the calls with Telecom/Core-Telecom.
- Screen behavior near a face: use the proximity sensor as a near-object signal, after checking sensor availability and range.
- Playback interruption or ducking: use audio focus for audio coordination, not as proof that a call began or ended.
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