Nightbell

A 24/7 AI voice agent for plumbing and HVAC companies. Answers every call in under two seconds, triages real emergencies from a versioned rule matrix, pages the on-call tech while coaching the caller, and books everything else straight into the schedule. Gas and CO calls hit a hard-coded safety route that a prompt cannot reach.

Twilio handles the number and SIP trunk. Vapi runs streaming speech to text with barge-in, so a caller can always interrupt. A Python service classifies each call against a triage matrix that is versioned in git and loaded at call start.

Gas and carbon monoxide calls take a separate hard-coded route: safety script, evacuate, owner notified, booking path unreachable by design. Every tool call lands in an append-only event log, and a weekly transcript sample scores triage accuracy before any matrix change deploys.