Synthflow no longer sells self-serve plans: its pricing page says “Enterprise contracts start at $30,000 annually.” If you liked building your own agent, Retell AI is the closest switch you can sign up for today; if you just want the phone answered and booked, a packaged AI receptionist such as Rosie or My AI Front Desk is simpler. If you also want the booking to turn into a quote and an invoice without retyping, look at a receptionist built into a CRM.
Below: what changed at Synthflow and when, the alternatives with their published prices as of October 2026, a worked monthly cost for a typical small business, and a fair verdict.
What changed at Synthflow?
Synthflow used to have a self-serve ladder. Its own blog, in July 2025, listed a Starter plan at $29 a month for 50 minutes, with Pro, Growth and Agency plans above it and a 14-day trial of Pro.
That ladder is gone. As of October 2026:
- The pricing page shows one tier: “Enterprise contracts start at $30,000 annually. Final pricing is scoped around call volume, concurrency, telephony setup, integrations, security needs, and launch support.”
- Synthflow’s billing docs say it “uses sales-led pricing,” and that “in-product reselling was removed on September 15, 2026, so Synthflow no longer bills your subaccounts.”
- Its concurrency docs say the earlier Pro, Growth and Agency plans “are no longer sold, and existing workspaces keep their limits.”
- A changelog entry of 29 July 2026 announced the end of custom pricing plans and Stripe-based reselling on 15 September 2026, and one of 25 August 2026 says accounts not on an enterprise plan now run on Synthflow’s own model, with GPT and other third-party models no longer available to them.
One loose end: Synthflow’s homepage FAQ still describes building an agent for free and then paying as you go. The pricing page and the billing docs say otherwise, so treat that FAQ as out of date and ask sales before you plan around it.
Who this hits: anyone who wanted to start small, and agencies that resold Synthflow to clients through its built-in billing. If that’s you, the question is which kind of replacement you need.
The three kinds of Synthflow alternative
Synthflow was a builder: you designed the agent, connected the phone number and wrote the prompts, in a visual interface. Its replacements fall into three groups.
1. Per-minute builders. The closest like-for-like. You still design the agent and pay by the minute. They suit you if you, or someone you pay, are comfortable with prompts, call flows and webhooks.
2. Packaged AI receptionists. A finished receptionist on a monthly plan. You fill in your business details and forward your calls. This is the fit when the job is “answer the phone, take a message, book the appointment.”
3. A receptionist inside a CRM. The receptionist books the job into the same system that sends the quote, the invoice and the review request. Worth it when the phone call is only the first step of the work you want handled.
Hear the receptionist take a real call — it rings your phone in about a minute.
Synthflow alternatives compared (published prices, October 2026)
| Tool | Type | Published price | What’s extra or limited | Self-serve |
|---|---|---|---|---|
| Retell AI | Builder | $0.07–$0.31 a minute; its calculator’s default comes to $0.11 | Price is voice + AI model, added up; the $0.11 default assumes your own phone carrier, and a Retell number ($2 a month) adds per-minute calling charges | Yes, $10 free credit |
| Bland AI | Builder | $0.14 a minute (Start, no platform fee); $0.12 on Build ($299 a month) | One inbound number included on Start; calling minutes billed at pass-through cost; transfers $0.05 a minute, but warm and live transfers and the appointment-scheduling step are Enterprise-only; Start capped at 100 calls a day | Yes |
| Smith.ai AI Receptionist | Packaged | Free for 25 calls a month; Pro $150 (75 calls), $270 (150 calls), $500 (300 calls) | Priced per call | Yes, free tier |
| Rosie | Packaged | $49 (250 min), $149 (1,000 min), $299 (2,000 min) a month | $49 plan texts callers an appointment link; booking straight onto your calendar and live transfer start at $149 | Yes, 7-day trial |
| My AI Front Desk | Packaged | $99 a month for 200 minutes, plus 1,000 overage credits | Extra minutes $0.25 each (25 credits at $0.01) | Yes, 7-day trial |
| Goodcall | Packaged | $79, $129, $299 a month, unlimited minutes | Priced by unique customers: 100, 500 or 2,000 a month, then 79¢, 26¢ or 15¢ each | Yes; a free demo agent, and you pay when you connect a number |
| Dialzara | Packaged | $29 (60 min) to $349 (1,000 min) a month | Overage $0.35–$0.48 a minute; the $29 plan has no calendar sync | Yes, 7-day trial |
| Stack Space | Inside a CRM | $30, $125, $355, $800 a month, AI receptionist on every plan | 45 / 250 / 900 / 1,500 minutes included; past that, prepaid packs at 17.9–24¢ a minute that never expire ($105 for 500), or the receptionist pauses until next cycle | Yes, no trial |
All prices are from each company’s own pricing page, opened 7 October 2026 (Goodcall’s rechecked 9 October 2026). They change often, so check before you buy.
What does it cost in a real month?
Take a small plumbing or cleaning business that gets about 130 calls a month at around three minutes each: roughly 400 minutes, from about 90 different callers, and it wants the AI to book appointments.
| Option | How the month adds up | About |
|---|---|---|
| Retell AI | 400 min × $0.11, on your own phone carrier | $44 + carrier, plus your build time |
| Bland AI (Start) | 400 min × $0.14, plus calling; can’t book below Enterprise | $56 + calling, no booking |
| Goodcall Starter | Flat while you stay under 100 unique callers, then 79¢ each (check that it covers booking) | $79 |
| My AI Front Desk | $99 + 160 minutes past its included credits × $0.25 | $139 |
| Rosie Scale | Booking onto the calendar; 1,000 min included | $149 (or $49 + overage if a texted booking link is enough) |
| Stack Space Starter | $125 (250 min, 800 texts) + about 210 more minutes a month from a 500-minute pack (21¢ a minute; we round each call up to the minute) | about $170 |
| Dialzara Pro | $99 (220 min) + 180 min × $0.45 | $180 |
| Smith.ai AI Pro | The 150-call tier | $270 |
So: the builders are cheapest per minute by a distance, and Goodcall is cheapest flat. Among finished receptionists that book, Stack Space lands mid-pack: dearer than My AI Front Desk and Rosie, cheaper than Dialzara and Smith.ai. What the extra buys is the rest of the job, in the same login: the quote, the invoice and the review request. (Launch at $30 plus a 500-minute pack would come to $135, but each call summary is two or three texts long, so Launch’s 150 texts a month would run out at this call volume.) With the builders, you design, test and fix the agent yourself, as you did on Synthflow; both have visual flow builders, so the switch is closer than it sounds.
Where Stack Space fits
Stack Space is a CRM with the AI receptionist built in, so the call starts the job instead of ending at a message. The receptionist Stax trains answers your line 24/7, books straight onto your calendar, emails the customer the confirmation and texts you a summary after each call (summaries count toward your plan’s text allowance). Then the same login sends the estimate, the invoice and the review request; see how a yes becomes a paid invoice. Every plan includes one voice number, there are no per-seat fees on any plan, and white-label reselling starts on the $355 Professional plan, which matters if you were reselling Synthflow and its built-in billing just went away. See white-label AI receptionist for how that works.
Where others are stronger: Retell and Bland give developers far more control of the call flow, and their per-minute rates beat our 17.9–24¢ minute packs on most setups. If you only want answering, Goodcall costs less, and Rosie’s $49 plan may too if a texted booking link is enough (its overage rate isn’t on the pricing page, so ask). There is no free trial with us; the plans are pay-first, monthly, and you cancel yourself.
How to choose
- You have a developer and want control: Retell AI or Bland AI. Budget for build and testing time as well as minutes.
- You want the phone answered this week, nothing else: a packaged receptionist. Check how each one counts usage (minutes, calls or unique callers) against your real call log before you pick.
- You want the calls to turn into booked, quoted and invoiced jobs without retyping: a receptionist inside a CRM, like Stack Space.
- You resold Synthflow to clients: check who bills the client now. Synthflow’s in-product reselling ended on 15 September 2026.
Whatever you pick, test it the same way: forward your line for a day, call it ten times with your real customers’ questions, and read every transcript. For the wider field, see our best AI receptionist in 2026 and how much an AI receptionist costs.
FAQ
How much does Synthflow cost now?
Synthflow’s pricing page says enterprise contracts start at $30,000 a year, priced around call volume, concurrency, telephony, integrations, security and launch support (October 2026). Its earlier Pro, Growth and Agency plans are no longer sold, though existing workspaces keep their limits.
Is Synthflow free?
Not for new production use, as of October 2026. Its billing docs describe sales-led pricing for new deployments. The homepage FAQ still mentions a free start, but that conflicts with the pricing page, so confirm with Synthflow’s sales team.
What is the cheapest Synthflow alternative?
Per minute, the builders: Retell AI lists $0.07–$0.31 a minute and Bland AI $0.14 on its no-fee Start plan, both plus calling costs. For a finished receptionist, Smith.ai has a free tier for 25 calls a month and Dialzara starts at $29 for 60 minutes.
Synthflow vs Retell AI: what’s the difference?
Both are builders for AI phone agents. Retell is self-serve and pay-per-minute today, with $10 of free credit; Synthflow is now enterprise-only from $30,000 a year. If you liked Synthflow’s builder but need to start small, Retell is the closest switch.
Can I keep my phone number if I switch?
Usually yes. Most of these tools work by forwarding your existing business number to them, so customers keep calling the number they know. Our guide to forwarding calls to an AI receptionist shows how on each carrier.