Spam Call Blocker is an Android application written in Kotlin that blocks unwanted incoming calls using a combination of local blocklists, pattern matching, and real-time checks against multiple online phone reputation services (UnknownPhone, Tellows, Truecaller, and regional directories). It registers a call screening service to intercept calls, evaluates them against user-defined rules and external APIs, and can block, mute, or answer-and-hangup spam calls. The app provides a full settings UI for managing blocked/whitelisted numbers, pattern-based blocking, API toggles, and export/import of configuration. It also includes a donation screen and automatic update checking via GitHub releases. The codebase is well-structured with clear separation of concerns, uses Kotlin coroutines for concurrent API checks, and supports multiple languages.