Step-by-step instructions to configure a live AI receptionist for an HVAC contractor. Use Retell AI or Synthflow — Joshua picks which to use per client.
Go to retellai.com → Sign up → Select "Outbound IVR" or "Inbound + Outbound" plan. The inbound plan is what you need for a receptionist. Monthly cost is ~$29–$79/month depending on call volume.
In the dashboard, go to Phone Numbers → Purchase Number. Choose a local area code for the client's market (e.g., 312 for Chicago). This number receives inbound calls — it becomes the business's AI phone line.
Cost: $1–$3/month depending on area code and type (local vs. toll-free).
Go to Agents → Create Agent. Name it after the business (e.g., "Arctic Air Cooling"). Use the Retell AI web UI to configure:
Agent Name: Arctic Air Cooling Role: "You are a friendly, professional receptionist for an HVAC company. You greet callers warmly, answer common questions about services, and book appointments into the company calendar." Personality: Professional, helpful, never flustered. Use first name. Background Noise Handling: Enabled Voicemail Detection: Enabled Interruptions: Allow (caller can interrupt the AI mid-sentence) End Call Prediction: Enabled (auto-ends when call is resolved) Fallback: "I didn't catch that — can you repeat?"
The call flow is the script the AI follows. For an HVAC contractor, use this structure:
Greeting: "Thanks for calling Arctic Air Cooling. How can I help you today?" Branch 1 — Emergency AC Repair: "If caller says 'broken', 'not working', 'no AC': → Ask: What's the address? → Ask: When did the problem start? → Ask: Is this residential or commercial? → Confirm earliest available slot → Get name and callback number → Confirm and close" Branch 2 — Schedule Maintenance: "If caller says 'maintenance', 'tune-up', 'annual service': → Ask: Is this for a home or business? → Show available dates from calendar → Confirm slot → Get name and number → Confirm and close" Branch 3 — Pricing: "If caller asks 'how much', 'cost', 'price': → Give two options: Basic ($129) or Priority ($199) → Offer to check availability → If not ready to book: capture name and number for follow-up" Fallback / Unclear: "I want to make sure you get the right help. Can you tell me what you're calling about?"
In Voice Settings: Select a voice. For service businesses, recommended voices:
Recommended (Retell AI): - "Allison" (female, US English, professional) - "James" (male, US English, warm) Settings: Speed: 0.95 (slightly slower than natural — clearer on phone) Temperature: 0.7 (balanced warmth and clarity) Pause between sentences: 300ms
In Phone Numbers → select the number → Assign to Agent. Select the HVAC agent you created. Toggle Forwarding to off (AI handles it). Set a voicemail greeting fallback for after-hours.
Call from your personal phone. Walk through each scenario: emergency, maintenance, pricing. Note any weird responses and edit the call flow. Retell AI has a "Test Call" button in the agent dashboard that simulates calls without needing a real phone number.
Checklist before going live:
In Webhooks / Integrations: Add a webhook URL for call summaries to go to the business owner. Alternatively, Retell AI has built-in email summaries — configure it to send to the client's email after every completed call.
Also enable: Call Recording Storage (to review bad calls) and CRM Integration (if client uses a CRM, push call notes there automatically).
Go to synthflow.ai → Sign up. Synthflow has a simpler UI than Retell AI — good for quickly spinning up demo agents. Plans start at ~$29/month for inbound voice AI.
In the sidebar: Create AI Agent → Inbound Voice Agent. Name it (e.g., "Arctic Air Cooling").
Agent Type: Inbound (receives calls) Industry: Home Services Template: Select "Appointment Booking" or start blank
Synthflow uses a prompt-based system rather than a visual flow builder. Paste this prompt template:
You are a friendly, professional AI receptionist for Arctic Air Cooling, a local HVAC contractor. Your goal is to answer every incoming call, respond to common questions, and book appointments. KEY FACTS: - Business: Arctic Air Cooling - Services: AC repair, annual maintenance, new installation - Pricing: Tune-up $129, Priority service $199 - Areas served: Riverton, Oak Park, Elm Heights - Emergency calls: same-day availability SCRIPT: Opening: "Thanks for calling Arctic Air. How can I help?" If caller asks about AC repair / broken / not working: → "I can help you get that scheduled. What's the address?" → Get name, number, and preferred time → Confirm the appointment If caller asks about maintenance / tune-up: → "Our annual tune-up is $129 and includes a full inspection. Would you like me to check availability?" → Show next available slots → Book appointment with name and phone If caller asks about pricing: → Give both options ($129 basic / $199 priority) → Offer availability check → If not ready: capture name + number for follow-up Closing: "You're all set — our technician will confirm before the visit. Anything else I can help with?" IMPORTANT: - Be warm and friendly - Always collect name + phone before confirming - If you don't understand, ask the caller to repeat - Never hang up on the caller
Synthflow provides a built-in phone number or lets you port an existing number. For the demo, use a Synthflow-provided number (available in most area codes). In Numbers → Assign to Agent.
In Voice Settings: Pick a voice. Synthflow uses ElevenLabs voices — excellent phone quality.
Recommended voice: "Rachel" or "Daniel" (ElevenLabs) Speed: Normal Fillers: "Um", "uh" removal enabled
Connect Google Calendar or Calendly so the AI can see real availability. In Integrations → Calendar → connect Google Calendar. The AI will then only offer slots that are actually open.
Use the Test Call button (Synthflow has a built-in simulator). Call the number, walk through all 3 scenarios. Adjust the prompt if the AI says anything weird. Once you're satisfied, toggle the agent to Active.
When setting up for a new client, customize these fields in the agent config:
BUSINESS INFO: □ Business name □ Industry / vertical □ Phone number (local area code) □ Hours of operation (AI routes differently after hours) □ Voicemail greeting SERVICES (AI needs to know what to offer): □ List of service offerings □ Pricing tiers □ Service area / zip codes □ Emergency vs. standard response CALENDAR / BOOKING: □ Preferred booking method (Calendly, Google Calendar, manual) □ Slot availability (days/times) □ Buffer time between appointments □ Cancellation policy FAQ RESPONSES: □ Common questions and answers (e.g., "Do you service my area?") □ Out-of-scope requests (e.g., "Can you fix my car?") □ Escalation path (when to transfer to human) FOLLOW-UP: □ Send summary email after each call □ SMS confirmation to customer (yes/no) □ CRM integration (push notes there) □ Reminder text 24h before appointment
When Joshua presents this to a prospective client, use the /demo page as the visual. Walk through scenario 1 (AC broke) to show the full call flow — greeting → address collection → appointment booking → confirmation. Then explain:
After the demo converts, configure the live agent with the client's actual business name, services, and phone number. Use the Retell AI or Synthflow setup above. Estimated setup time: 45–60 minutes per new client.
Tip: Build a "client onboarding template" in Retell AI or Synthflow that has the base HVAC script pre-loaded — then you just swap the business name, phone number, and pricing. Reuse across clients.