Step-by-step guide to setting up a working voice AI agent in Synthflow
Go to synthflow.ai and click "Start Now". No credit card required to start.
Choose the Pay As You Go plan — this is best for demos and pilots. You only pay for what you use, and billing starts after your first real call.
Cost estimate for a demo agent: ~$0.14/minute. A 2-minute test call costs about $0.28.
In the Synthflow dashboard, click Create Agent. Give it a name like "HVAC Receptionist" or "Roofing Intake Agent". Select Appointment Booking as the primary use case.
For call type, choose Inbound Calls — this is how most service businesses use AI agents (customers call in, AI answers and books).
Navigate to the Global Settings tab in the agent builder. This is where you define who the AI is, how it speaks, and what it does.
Copy these into the Global Settings → "Who You Are" and "Greeting" fields:
AI Identity:
You are [Business Name]'s friendly AI receptionist. You help callers schedule heating and cooling service appointments. Be warm, professional, and concise. Always confirm the appointment details before ending the call.
Greeting Script:
AI: "Thanks for calling [Business Name]. This is [Name], your AI assistant. Are you looking to schedule a service appointment today?"
If caller says yes: "Great, I can help you with that. What's the service you need — repair, maintenance, or a new installation?"
Collect (in order):
1. Service type (repair/maintenance/installation)
2. Caller name and address
3. Description of the problem
4. Preferred date/time
AI: "All set — I've got you booked for [Date] at [Time]. [Name] will arrive at [Address] for your [Service] appointment. You'll receive a text confirmation shortly. Anything else I can help with?"
Closing: "Thanks for calling [Business Name]. See you on [Date]!"
AI Identity:
You are [Business Name]'s AI assistant. You help homeowners schedule free roof inspections and estimates. Be friendly, professional, and knowledgeable about common roofing issues. Always emphasize the free, no-obligation nature of the inspection.
Greeting Script:
AI: "Thanks for calling [Business Name]. I'm here to help you schedule a free roof inspection or estimate. Are you looking to get that scheduled?"
If caller says yes: "Excellent. Let me gather a few details to set that up. What's your name, and what's the property address?"
Collect (in order):
1. Caller name and property address
2. Type of issue (leaking, missing shingles, age of roof, storm damage)
3. Homeowner or renter
4. Preferred date/time for inspection
AI: "Your free roof inspection is confirmed for [Date] at [Time] at [Address]. Our team will arrive between [Time] and [Time+1hr] to do a thorough inspection at no charge. You'll get a text reminder the day before. Anything else?"
Closing: "Thanks for calling [Business Name]. We'll see you on [Date] for your free inspection!"
In the agent builder, go to Actions → Real-Time Booking. This lets the AI see your actual availability and book directly into your calendar.
Options:
After the AI books an appointment, it should automatically send a text confirmation to the caller. In the agent builder, go to Actions → SMS.
Configure this trigger: "After successful appointment booking"
SMS Template (HVAC):
"Hi [Name], this is [Business Name] confirming your [Service] appointment on [Date] at [Time]. Our technician will arrive at [Address]. Reply CANCEL to cancel. We look forward to seeing you!"
SMS Template (Roofing):
"Hi [Name], [Business Name] here. Your free roof inspection is confirmed for [Date] at [Time] at [Address]. We'll text you a reminder the day before. Reply CANCEL to cancel."
Go to Test Center in the Synthflow dashboard. You can simulate a call with the AI — type your responses instead of speaking, which makes testing fast and iterative.
Test the full flow:
If something goes wrong, go back and adjust the script. The Test Center shows you exactly what the AI said and did, so you can iterate quickly.
Point your Synthflow agent's webhook to the CallMend dashboard so call events appear in real time:
POST https://callmend-3.polsia.app/webhooks/synthflow
In Synthflow: Settings → Webhooks → Add Webhook. Paste the URL above. Select events: Call Completed, Booking Made.
The webhook fires on every call, sending call metadata (duration, outcome, caller phone) to your dashboard at /demo.
For real inbound calls, you need a phone number that routes to your AI agent:
Once your number is connected, your AI agent answers every call, 24/7. No staff required for intake calls.
Once your agent is running, share the demo URL with prospects:
https://callmend-3.polsia.app/demo