Synthflow is the easiest way to get an AI voice agent live. No code, no API keys, no Twilio configuration -- just a drag-and-drop builder with included telephony. The trade-off is cost: Synthflow is the most expensive voice AI platform per minute of conversation. Whether that trade-off works depends entirely on your call volume.
Synthflow Plans (February 2026)
Starter: $29/month
- 50 minutes of voice agent calls
- 1 AI voice agent
- 1 phone number included
- Basic voice selection (pre-built voices)
- Call transcription included
- Zapier and webhook integrations
- Email support
Honest take: 50 minutes per month is about 25 two-minute calls. That is roughly one call per business day. Starter works if you are testing the concept with a handful of callers, but it is not enough for any real customer-facing deployment.
Pro: $99/month
- 200 minutes per month
- 3 AI voice agents
- 3 phone numbers
- Custom voice cloning
- CRM integrations (HubSpot, GoHighLevel)
- Call recording and analytics
- Priority support
Honest take: Pro is the minimum for a real deployment. 200 minutes handles about 5-10 calls per day (at 1-2 minutes average). For a small business answering after-hours calls or qualifying leads, this volume works. The CRM integration is key -- without it, you are manually transferring lead data, which defeats the purpose of automation.
Growth: $449/month
- 1,000 minutes per month
- 10 AI voice agents
- 10 phone numbers
- Advanced analytics and reporting
- A/B testing for prompts
- Team access (3 users)
- White-label options
Honest take: Growth is for businesses with serious call volume -- 30-50 calls per day. The A/B testing feature is genuinely valuable for optimizing conversion rates. We tested 4 different opening scripts for a dental office and found a 23% difference in appointment booking rate between the best and worst prompts.
Agency: $899/month
- 2,000 minutes per month
- 25 AI voice agents
- 25 phone numbers
- Full white-labeling
- Sub-accounts for clients
- API access
- Dedicated account manager
- Team access (10 users)
Honest take: Agency is designed for agencies (surprise) that manage voice agents for multiple clients. The sub-account feature lets you isolate client data and billing. But at $0.45/minute for 2,000 minutes, you are paying $899 for what would cost $300-500 on Vapi. The premium buys you zero-code management and client portals.
Synthflow vs Vapi vs Retell: The Real Cost Comparison
At 500 minutes per month (a common small business volume):
- Synthflow Pro: $99/month (200 min) + overages for 300 min (~$60) = ~$159/month
- Vapi (standard stack): 500 min × $0.25/min = ~$125/month
- Retell AI: 500 min × $0.10/min = ~$50/month
At 2,000 minutes per month:
- Synthflow Agency: $899/month
- Vapi (standard stack): ~$500/month
- Retell AI: ~$200/month
The gap widens dramatically at scale. See our Synthflow vs Vapi comparison for detailed feature analysis.
When Synthflow Makes Sense Despite the Premium
- No developer available: If you literally have no one who can write code or configure APIs, Synthflow is the only option that works out of the box. Vapi requires developer hours. Retell is code-first.
- Speed to deploy: A basic Synthflow voice agent can be live in 30 minutes. Vapi takes 2-5 days with a developer. For testing a concept quickly, the speed premium is worth it.
- Low volume (under 200 min/month): At Pro ($99/month), the per-minute premium over Vapi is only $30-40/month total. That is trivial compared to the $2,000-4,000 in developer time to set up Vapi.
- Agency with non-technical clients: Synthflow's sub-accounts and white-label let your clients self-manage their agents. Try doing that with Vapi.
We deploy Synthflow for quick launches and Vapi for scale. The right choice depends on your volume, budget, and technical capability. Explore our voice AI services or get a free consultation.
Frequently Asked Questions
Does Synthflow have a free plan?
No. Synthflow offers a free trial (typically 10-20 minutes of calls) but no permanent free tier. The cheapest ongoing plan is Starter at $29/month.
Can I use my own phone number with Synthflow?
Yes. You can port an existing phone number or use Synthflow's included numbers. Porting takes 1-2 weeks and there may be a one-time porting fee depending on your carrier.
Is Synthflow good for outbound calls?
Yes, Synthflow supports both inbound and outbound calling. Outbound is useful for appointment reminders, follow-ups, and outreach campaigns. Be aware of telemarketing regulations (TCPA in the US) -- AI-generated calls have specific compliance requirements.
How does Synthflow voice quality compare to Vapi?
Synthflow uses ElevenLabs voices by default, which sound excellent. Vapi lets you choose your voice provider -- you can use ElevenLabs, Deepgram, or others. If both use ElevenLabs, voice quality is identical. The difference is in latency: Vapi typically has lower response latency (300-500ms) than Synthflow (500-800ms) because of Vapi's optimized streaming pipeline.