Whitelist-based call protection for Android
Block every unknown caller. Let only your contacts through.
CallBlocker registers as Android's CallScreeningService. Every incoming call is intercepted before the phone rings:
- If protection is suspended → allow
- If suspended by schedule → allow / block per rule
- If the number is in system contacts → allow
- If the number is in the custom whitelist → allow
- If the user recently called that number → allow (optional)
- If STIR/SHAKEN attestation is FAILED → block (optional)
- Otherwise → block silently (no ring, caller hears busy tone)
- Whitelist-based blocking — only allowed numbers can reach you
- One-tap toggle — enable or disable protection instantly from the home screen
- Temporary suspension — pause protection for 1 h / 3 h / 24 h or a custom duration
- Add numbers manually or import from device contacts
- Edit or delete individual entries
- Full-text search
- Per-call detail view with block reason, timestamp, SIM slot
- Configurable log retention (7 / 30 / 90 days or forever)
- Delete individual entries or clear all
| Rule | Description |
|---|---|
| Retry rule | Allow a blocked number through after N attempts within M minutes |
| Dialed-number whitelist | Auto-allow numbers you called in the last 1 / 6 / 24 / 48 hours |
| STIR/SHAKEN | Block calls flagged as verification failed by the carrier |
- Define time windows (e.g. nights, weekends) for automatic enable/disable
- Per-day and per-time-range rules with exact
AlarmManagertriggers - One-tap override for today or permanently
- Choose which SIM slot(s) to protect (SIM 1 / SIM 2 / Both)
- MIUI-compatible SIM detection via CallLog accountId mapping (ICCID not required)
- Per-feature SIM targeting for STIR/SHAKEN, dialed whitelist, and schedule rules
| Widget | Size | Description |
|---|---|---|
| Toggle | 2×1 | One-tap on/off — no need to open the app |
| Status | 2×2 | Protection state, whitelist count, last blocked call |
Both widgets are compatible with MIUI/HyperOS launchers.
- Optional notification when a call is blocked
- Optional notification when a new app update is available
| Action | What it saves |
|---|---|
| Export whitelist | Allowed contacts as JSON |
| Import whitelist | Restore contacts (overwrites current list) |
| Export all settings | Every preference (toggle states, rules, language, etc.) as JSON |
| Import all settings | Restore complete configuration — useful after reinstall or new device |
| Auto-backup | Whitelist exported automatically on a schedule (daily / weekly / monthly) |
- English and Italian included
- System language auto-detection
- Android 10 (API 29) or higher
- The CallScreeningService role must be granted — the app will prompt you on first launch
Note on MIUI / HyperOS: The system Quick Settings toggle may not reliably activate the role. The dedicated home screen Toggle widget is the recommended alternative.
| Permission | Why it is needed |
|---|---|
READ_CONTACTS |
Import contacts into the whitelist |
READ_CALL_LOG |
Blocked call history; SIM slot detection on MIUI; dialed-number whitelist |
READ_PHONE_STATE |
Detect active SIM subscriptions for dual-SIM support |
POST_NOTIFICATIONS |
Show block notifications (Android 13+) |
RECEIVE_BOOT_COMPLETED |
Re-activate the screening role after reboot (opt-in) |
INTERNET |
Check for app updates (opt-in only) |
- Download the latest APK from the Releases page.
- Enable Install from unknown sources in Android Settings → Security.
- Install the APK and open the app.
- Tap Activate and grant the Call Screening role when prompted.
- Add your allowed contacts and enable protection.
git clone https://github.com/amlet/callblocker.git
cd callblocker
./gradlew assembleDebugRequirements: Android Studio Hedgehog 2023.1.1+ · JDK 17 · Min SDK 29 · Target SDK 34
| Layer | Technology |
|---|---|
| UI | Jetpack Compose, Material 3, Navigation Compose |
| Architecture | MVVM, StateFlow, Coroutines |
| Database | Room (SQLite) |
| Preferences | SharedPreferences |
| Serialization | kotlinx.serialization (JSON backup) |
| Call blocking | CallScreeningService (Android Telecom API) |
| Scheduling | AlarmManager.setExactAndAllowWhileIdle() |
| Background work | WorkManager (auto-backup, update check) |
src/main/
├── java/com/amlet/callblocker/
│ ├── data/
│ │ ├── backup/ BackupManager (JSON export/import)
│ │ ├── changelog/ In-app changelog data
│ │ ├── db/ Room database, DAOs, entities
│ │ ├── prefs/ AppPreferences (SharedPreferences wrapper)
│ │ └── repository/ ContactRepository
│ ├── service/
│ │ ├── CallBlockerService Core CallScreeningService implementation
│ │ ├── BootReceiver Re-prompts for role on boot
│ │ ├── ScheduleAlarmReceiver
│ │ └── ScheduleManager
│ ├── ui/
│ │ ├── components/ Reusable Compose components
│ │ ├── screens/ Home, Contacts, Call Log, Settings, etc.
│ │ ├── theme/ Color, Typography, Theme
│ │ └── viewmodel/ ContactViewModel
│ ├── widget/
│ │ ├── ToggleWidgetProvider 2×1 on/off widget
│ │ └── StatusWidgetProvider 2×2 info widget
│ ├── util/ LocaleHelper, NotificationHelper, PhoneUtils, UpdateChecker
│ └── worker/ AutoBackupWorker, UpdateCheckWorker
└── res/
├── drawable/ Vector icons, launcher foreground
├── layout/ Widget layouts
├── values/ Strings (EN), colors, themes
├── values-it/ Strings (IT)
└── xml/ Widget provider metadata, backup rules
MIT — see LICENSE for details.
App developed by Amlet