Building in a Safety-Critical Branch a Generic Prompt Would Miss

I want to build an AI voice agent for qualifying leads for a plumbing business, specifically for after-hours calls when no one's available live. Design the conversation flow: the opening line, the 3-5 key branches it needs to handle, a fallback for when it doesn't understand the caller, and how it should hand off to a human.

Opening line: "You've reached [Business Name] after hours — I can take down details and get you a callback. If this is a flooding or burst-pipe emergency, say 'emergency' now."

Key branches: (1) Emergency (flooding, burst pipe, no water/heat in freezing weather) — bypass everything else, trigger an immediate SMS/call to the on-call plumber; (2) Non-urgent quote request — capture job description, address, and callback time preference; (3) Existing customer follow-up — log the reference and pass to the office in the morning; (4) General inquiry — take a message.

Fallback: "Just to make sure I route this correctly — is this urgent, like active flooding, or can it wait until our next business day?"

Human handoff: Emergencies skip the overnight queue entirely and page the on-call plumber directly, rather than waiting for a morning callback like every other call type.