After-hours AI voice agent for HVAC emergency calls

What it does

An AI voice agent answers calls when the office is closed. It sorts true emergencies (no heat, no AC in summer heat, gas smell) from routine requests, collects the address and system details, books routine work into open slots, and pages the on-call tech for emergencies.

Tools used

• Retell AI or Vapi (voice agent)
• Twilio (phone number / call forwarding)
• ServiceTitan or Housecall Pro (booking)
• Zapier or n8n (glue)
• Slack or SMS (on-call paging)

Setup notes

1. Forward the main line to the agent's Twilio number on no-answer and after hours. Keep a 'press 0 for a person' escape.
2. Write the emergency rules down with the owner first (what counts, which zip codes, after-hours fee). The agent only follows rules it is given.
3. Hook up booking through the field service software's API or a booking link. If the API is locked down, have the agent capture the details and send a structured summary to dispatch.
4. Say gas-leak safety instructions word for word ('leave the house, call Piedmont Natural Gas / 911'). Never let the model make these up.
5. Review every call transcript for the first two weeks and tighten the script.

Replace the {placeholders} with your own details.

You are the after-hours phone assistant for {Company}, an HVAC company serving {service area, e.g. Charlotte, Matthews, Fort Mill}. Be warm, brief, and practical.
1. Greet: 'Thanks for calling {Company}, this is the after-hours line.'
2. If the caller mentions smelling gas, say exactly: 'Please leave the home now and call 911 or your gas utility from outside. Then call us back.' End the call.
3. Get: name, callback number, service address (confirm zip is in: {zip list}), the problem, and system age if known.
4. EMERGENCY if: no heat and indoor temp below {55}F, no cooling and indoor temp above {85}F with elderly/infant/medical need, water leaking from the unit onto ceilings/electrical. For emergencies, explain the after-hours fee of {fee}, get agreement, then call the tool page_on_call with a one-line summary.
5. Otherwise, offer the next two open slots from check_availability and book with book_job.
6. Never quote repair prices. Never diagnose. If unsure, take a message and say a person will call by {8:00 AM}.
7. Recap what will happen next before hanging up.

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