Why We Built a 100% On-Device, Zero-Tracker Call Manager

When looking at third-party caller ID and call screening apps on mobile platforms, a troubling pattern emerges: many apps require users to upload their entire address book to remote company servers. Contact numbers, family relationships, and personal call habits are aggregated, monetized, or shared with third-party advertising brokers.

At Tekromancy, we firmly rejected that architecture.

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The Power of Android Telecom CallScreeningService

Introduced in modern Android versions, CallScreeningService allows designated applications to act as a system screening component:

• When an incoming call arrives, the Android Telecom framework passes metadata directly into the app’s onScreenCall(details) callback.
• The app evaluates whether to silence, vibrate, reject, or allow the call.
• The decision is returned to the OS, which executes the action before the user’s phone even rings.

Because this happens directly within the Android OS telecom stack, there is zero need to continuously read the system Call Log, listen to raw phone state broadcasts, or transmit phone numbers across the internet.

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Our Zero-Cloud Privacy Commitment

1. No External Servers: Silent Mode Control does not run backend databases or servers that receive user data.
2. Local Room SQLite Storage: All groups, contact rules, and historical audit records reside exclusively in encrypted local app storage.
3. No Third-Party Analytics or Ad SDKs: We do not include Firebase Analytics, Crashlytics, AdMob, or tracking pixels.
4. On-Demand Data Purge: Users can delete all screening logs with a single tap in the app.

We believe that software should serve the person holding the phone—nobody else.