callshield

CallShield is an open-source Android app that blocks spam calls and flags spam texts using an on-device engine with over 30 detection layers. It includes a gradient-boosted tree ML scorer, campaign and churn detection, carrier identity signals, an RCS notification filter, and real-time caller ID. The app maintains a database of 51,363 spam numbers alongside a trending-numbers feed checked every 30 minutes. No accounts or tracking are required. The spam database is distributed via signed, content-addressed shards with a hash manifest, verified against an embedded ECDSA P-256 key. Devices fetch only changed shards and fall back to a legacy snapshot when needed. Key features include: - **Detection pipeline**: Priority-ordered layers covering emergency numbers, whitelists, STIR/SHAKEN, user/system blocklists, wildcard/regex rules, prefix rules, spam database, heuristics, campaign burst detection, ML scoring, and more. - **Live caller ID overlay**: Shows verdicts as calls ring, with optional SkipCalls enrichment and SIT tone playback. - **Protection levels**: Recommended, Strict, or Contacts-only, switchable with undo. - **SMS screening**: Flags spam texts via content analysis, burst protection, carrier scam labels, and notification screening for messaging apps. - **Per-rule schedules**: Time-gate wildcard, range, and SMS keyword rules. - **Community-driven**: One-tap anonymous reports via a Cloudflare Worker. Setup requires phone/SMS permissions and the Call Screening role on supported Android versions. The app targets Android 10+ and is MIT-licensed.