ScamShield: Live Voice Guardian vs Phone Scams

Phone scams succeed during the call: a fake bank employee, a "locked" account, a code "just sent to your phone". By the time anyone checks, the money is gone, and older people are targeted most. ScamShield runs on a phone or laptop next to the call. The call is put on speaker and streamed live to AssemblyAI Universal-Streaming. Every partial transcript is checked instantly for scam tactics: requests for a verification code, PIN, card details, remote access, gift cards or crypto, and money under pressure. An AI second opinion reads the whole call at each end of turn. When the risk becomes critical, ScamShield chimes, turns the call audio down, shows a full-screen "Stop — possible scam" alert explaining what is happening, why it is dangerous and what to do, and speaks a short warning out loud. Key features: - Words appear about 0.5 s after they are spoken; the alarm shows its measured latency - Ask "ScamShield, is this real?" during the call and it answers out loud - Urdu / Hindi support (beta) with a spoken Urdu warning - The AI can only raise risk, never lower it, so a scammer cannot talk it down - After-call report with a timeline, shareable with family on WhatsApp - Private: no recordings or transcripts are stored; the AI check can be switched off AssemblyAI features used: Universal-Streaming v3, partial transcripts, end-of-turn detection, formatted turns, speaker labels, keyterm prompting, the multilingual u3-rt-pro model, word timestamps and temporary tokens. Results: 18/18 scams caught on a blind test set (rules + AI), 0 false alarms from the rules on 63 genuine calls, and 144 automated tests passing.