Android application
PrefixBlocker
An application designed to block telemarketing calls based on prefixes, without transmitting your personal data.
Version 1.3
Last updated: May 2026
Prefix-based blocking
PrefixBlocker uses Android's call screening service to identify numbers matching the prefixes configured by the user.
Protected contacts
Your contacts can be used as a local whitelist so personal numbers are not blocked.
No transmission
The application does not request the INTERNET permission: data stays on your phone.
Overview
PrefixBlocker helps reduce unwanted calls by blocking numbers whose prefix matches your rules. The application runs locally on the device and does not rely on a remote service.
Privacy Policy
PrefixBlocker is designed to protect user privacy. This policy explains how data is used by the application.
Read the full policyCall data
The application uses the CallScreeningService API to identify and block telemarketing numbers based on prefixes. No call content is listened to, recorded, or analyzed.
Contacts
Access to contacts is requested only to create a local whitelist. This prevents personal contacts from being blocked. This data remains on your device and is never transmitted.
No transmission
The application does not request the INTERNET permission. No data, including blocked numbers, contacts, or statistics, leaves your phone.
Local storage
The blocked call history is stored locally in the application's secure storage.
Locally stored data
Blocking rules, the whitelist, and any history remain in the application's storage on the device.
Deletion
The blocked call history can be deleted at any time by the user from the application.
Data sharing
No data is shared with third parties, because the publisher does not have access to the data stored locally by PrefixBlocker.
Contact
For any question about PrefixBlocker or this privacy policy, please contact the publisher:
laurent@kstl.fr