How to Build a Voice Bot for HVAC Customer Inquiries with VAPI TL;DR Most HVAC support lines drop 40% of inbound calls during peak season. Build a voice bot that handles appointment scheduling, service history lookups, and emergency triage without human intervention. Stack VAPI's LLM-powered agent with Twilio's SIP trunking to route calls directly into your existing phone infrastructure. Result: 24/7 availability, zero dropped calls, and your team handles only complex issues. Prerequisites API Keys & Credentials You'll need a VAPI API key (grab it from your VAPI dashboard) and a Twilio account with an active phone number and API credentials (Account SID and Auth Token). Store these in a .env file—never hardcode them. System Requirements Node.js 16+ with npm or yarn. A server capable of receiving webhooks (ngrok works for local testing, but use a real domain in production). HTTPS is mandatory—Twilio and VAPI reject HTTP callbacks.…