How I Built an AI Phone Agent That Answers Calls for Contractors at 2 AM

Last month, I launched OnCrew — an AI-powered phone answering service built specifically for home service contractors (HVAC, plumbing, electrical, roofing).

Here is the problem I set out to solve and how I built it.

The Problem

A plumber in Van Nuys finishes a 12-hour day at 8 PM. He silences his phone. At 2 AM, a homeowner pipe bursts. They call. Voicemail. They call the next plumber on Google. That first plumber just lost a $4,200 emergency job in his sleep.

This happens thousands of times every night across LA alone. Contractors miss 40-60% of after-hours calls, and each missed call is worth $800-4,200 in lost revenue.

Traditional answering services charge $1-2 per minute and employ people reading scripts who cannot tell a burst pipe from a dripping faucet.

The Solution: OnCrew

OnCrew is an AI phone agent that:

• Answers every call 24/7 — no hold music, no voicemail
• Understands trade-specific language — knows the difference between a burst pipe and a quote request
• Triages by urgency — real emergencies get dispatched immediately, quotes get scheduled
• Dispatches the nearest tech in 90 seconds
• Costs $49/month flat — no per-minute billing

Tech Stack

• Frontend: Next.js 16 on Vercel
• Voice AI: Retell AI with custom Claude-powered LLM
• Telephony: Twilio for phone numbers and call routing
• Payments: Stripe with 14-day free trial
• Database: Supabase
• Notifications: Telegram bot for real-time alerts

How the AI Works

When a call comes in:

1. Retell AI picks up and greets the caller naturally
2. The AI asks targeted questions based on the trade (HVAC, plumbing, electrical)
3. It classifies the call: emergency, urgent, or routine
4. For emergencies: immediately notifies the contractor and dispatches
5. For routine calls: books an appointment or takes a message

The AI (we named her Sarah) uses Claude as the underlying LLM with contractor-specific knowledge. She knows that no hot water in January is more urgent than in July. She knows a panel buzzing smell means dispatch now.

Results So Far

We just launched, so I am being honest — zero paying customers yet. But the tech works. You can call (818) 578-4783 right now and talk to Sarah yourself.

What I can tell you:

• Call pickup time: less than 1 second
• Available: 24/7/365
• Cost: $49/mo flat (vs $200-500/mo for human answering services)

What I Learned Building This

1. Contractors do not care about AI — they care about not missing calls.
2. Voice AI has gotten scary good — Retell + Claude produces conversations hard to distinguish from human.
3. The trades are massively underserved by tech — most software is designed for office managers, not the guy in the truck at 8 PM.
4. SEO for a new domain is brutal — fighting established players with similar names.

Try It

Check out OnCrew. 14-day free trial, no credit card required.

Or call (818) 578-4783 and see for yourself. Sarah picks up on the first ring.

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Building in public. Follow along: @OnCrewAI