Built at Fireworks: Deploy with Microsoft & NVIDIA

Emberz: a fine-tuned guardian for live phone-call ── safety

Emberz gives your kid, your grandma or you a guarded phone number. Every call passes through our line: NVIDIA Nemotron Speech transcribes both sides live, and a guardian model we fine-tuned on Fireworks reads every turn. It stays quiet on normal calls. When a call turns into a scam, a grooming pattern, a threat or an info grab, it whispers a tip only the protected person hears and alerts the caretaker, who can listen in and join from a live console. Caretakers write the rules in plain words ("never share the door code", "Grandpa is allowed"). An AI-voice detector flags synthetic callers in the first seconds of the call. The guardian is Qwen3.6-35B-A3B with a LoRA we trained on the Fireworks serverless Training API, using 1,440 calls generated from a 75-scenario taxonomy grounded in the FBI IC3 2025 report. We tested it on 257 held-out calls written by a different model family, NVIDIA Nemotron 3 Ultra. Results: it handles 90.3% of held-out calls correctly, against 75.5% for the same model untuned (+14.8 points) and 83.7% for Kimi K3 (+6.6). False alarms fall from 53% to 18%, and it gets 19 of 22 caretaker-rule pairs right, against 5 or fewer for every off-the-shelf model. McNemar's test and a scenario-clustered bootstrap confirm every gain. On BothBosu, a public dataset it never saw, it catches 98 of 100 scams with zero false alarms. Paper: https://github.com/matt-ceran/emberz/blob/main/callguard/docs/emberz_submission.pdf