iOG26 Call Filter

iOG26 is a simple Android app designed to block unwanted phone calls automatically. It helps you maintain your peace by filtering out spam, anonymous callers, unknown (not-in-contacts) callers, and specific numbers/prefixes you choose to block.

Key Features

• Block anonymous/private callers: Automatically block calls with hidden/withheld caller ID or when the system marks the presentation as restricted/unknown/payphone. This is different from “not in your contacts”.
• Block unknown numbers (not in contacts): New. Optionally block any number that is not saved in your contacts. Requires READ_CONTACTS permission.
• Custom Blocklists:
  • Numbers: Add specific phone numbers to a personal blocklist.
  • Prefixes: Block all calls that start with a certain country or area code (e.g., +1-800).
• History & Dashboard: A detailed history and a new dashboard with animated charts (blocks per day, caller type breakdown), key metrics (total, avg/day, number of countries, last block date/time), and a Top Countries card.
• Daily Digest: Get a daily notification that summarizes all the blocked call activity from the day.
• Customizable Settings:
  • Choose whether blocked calls appear in your phone's call log.
  • Decide if you want to receive a silent notification when a call is blocked.
  • Set the time for your daily digest.
• Internationalization (ES/EN/IT): Complete translations for Spanish, English and Italian.

How Call Blocking Works

• The checks are performed in this order:
  1. Is the call anonymous/hidden and is that setting enabled?
  2. Is the number in the blocked numbers list?
  3. Does it start with a blocked prefix?
  4. If the "Block unknown numbers" setting is enabled, is the number NOT in your contacts?

Privacy

• All decisions are made on-device. Blocklists and history are stored locally using Room.
• The app does not upload your call data to any server.
• Dedicated in-app Privacy Policy screen, localized in Spanish, English, and Italian. The full policy text is bundled offline and shown from Settings.

Permissions

• READ_CONTACTS: Required only if you enable "Block unknown numbers" (to check whether a caller exists in your contacts). Requested at runtime on first enable.
• POST_NOTIFICATIONS (Android 13+): For optional notifications when a call is blocked and for the daily digest.
• RECEIVE_BOOT_COMPLETED: To re-schedule the daily digest after device reboot.
• Call screening role: The app must be set as the default Caller ID & spam app so Android routes calls to the screening service.

Limitations & Compatibility

• iOG26 must be set as the default “Caller ID & spam” app; otherwise, Android won’t invoke the screening service.
• Some third‑party VoIP calls may not be routed through Android’s CallScreeningService and cannot be blocked by this app.
• Behavior may vary across OEMs/ROMs. On some devices, silencing plus rejecting improves reliability (the app already attempts this where supported).
• Emergency numbers are never blocked.

Technical Overview

This section details the app's architecture and the technical flow behind the call-blocking functionality.

Core Components

• CallScreeningService: This is the heart of the call-blocking feature. It's an implementation of Android's native CallScreeningService API, which allows a designated app to inspect incoming calls and decide whether to allow, reject or silence them before they ring.

• Room Database (AppDb): A local database built with Jetpack Room that stores all user-defined rules and app data:

  • Blocked Numbers: A list of specific phone numbers to block.
  • Blocked Prefixes: A list of prefixes (like country or area codes) to block.
  • Blocked History: A log of every call that has been blocked, including the number and timestamp.

• BlockRepository: Acts as a single source of truth for the app's data. It abstracts the data sources (the Room database) from the rest of the app, providing a clean API for data access.

• UI (Jetpack Compose): The entire user interface is built with Jetpack Compose, a modern, declarative UI toolkit. ViewModels are used to manage the state and logic for each screen, exposing data to the UI via StateFlow.

• WorkManager + BroadcastReceiver: A periodic/background task schedules the daily digest. On boot, BootReceiver re-initializes scheduling. The worker queries recent blocked events and posts a localized summary notification at the user-defined time.

How Call Blocking Works

The app intervenes in the native call flow at the earliest possible moment, which is key to its effectiveness and seamless operation.

1. User Designation: For the app to function, the user must first set it as their default "Caller ID & spam app" in the phone's settings. This registers the app's CallScreeningService with the Android system.

2. Incoming Call Trigger: When the device receives an incoming call, the Android telephony system checks for a registered CallScreeningService. Since iOG26 is designated, the system invokes the onScreenCall method in our service.

3. Real-Time Decision: Inside onScreenCall, the service receives the incoming phone number.

   • The service immediately queries the BlockRepository to check the number against the user's rules stored in the Room database.
   • The checks are performed in a specific order: Is it anonymous/private (if enabled)? Is the number in the blocked numbers list? Does it start with a blocked prefix? If "Block unknown numbers" is enabled and the app has READ_CONTACTS permission, is the number not found in the user's contacts?

4. Executing the Block:

   • If any of the rules match, the service constructs a CallResponse with setDisallowCall(true). This instructs the system to terminate the call immediately and silently.
   • Based on user settings, the response can also include setSkipCallLog(true) to prevent the blocked call from ever appearing in the phone's native call history, making the block truly invisible.
   • If no rules match, the call is allowed to proceed normally without any intervention.

5. Logging the Event: If a call is disallowed, the service records the event by adding a new BlockedEvent entry to the Room database. This allows the user to see what the app has done in the "History" screen.

This approach is highly efficient because it leverages a native Android API designed specifically for this purpose. It makes a decision in milliseconds, before the phone even starts ringing, ensuring a non-intrusive experience for the user.