The best AI voice agents, tested and ranked
We built the same phone booking agent on six AI voice agent platforms and put each through the same 20 tricky test calls. Here's which one handled callers best and what each costs to start.
About this list
An AI voice agent answers and places phone calls for you. It listens with speech recognition, decides what to say with a language model and replies in a synthetic voice, so it can book appointments, qualify leads or answer support questions without a person on the line. You'll find more tools like this in our AI voice agents section and the wider AI video and audio hub.
These platforms look alike on their home pages but suit very different buyers. Some are developer kits where you pick every part, some give you a visual builder, and some are managed services where the vendor builds and runs the agent. Pricing varies just as much, from bundled per-minute rates to quote-only yearly contracts.
To compare them fairly, we built the same phone booking agent for a made-up online store on every platform and put it through the same 20 scripted test calls, from October 20 to October 26, 2026.
Compare at a glance
| # | Tool | Best for | Cheapest way to start | Score |
|---|---|---|---|---|
| 1 | Retell AI | Best overall | Free | 3.0 |
| 2 | PolyAI | Best for large contact centres | No public price | 3.0 |
| 3 | Synthflow | Best for non-technical teams | No public price | 3.0 |
| 4 | Bland AI | Best for regulated enterprises | $299 a month (Build) | 2.5 |
| 5 | Dapta | Best for WhatsApp sales follow-up | $99 a month (Pro) | 2.5 |
| 6 | Vapi | Best for developers | $29 a month (Core) | 2.0 |
Features and terms compared
These facts come from each company's own pages and our research, with prices checked on November 2 and 3, 2026.
| Tool | Starting price | Free credit or plan | Build style | HIPAA and SOC 2 | Trustpilot score |
|---|---|---|---|---|---|
| Retell AI | No monthly fee; about $0.07 to $0.31 a minute all in | $10 in free credits and 20 free concurrent calls | Visual flow builder and API | SOC 2 Type II; HIPAA with a signed BAA | 4.9 (805 reviews) |
| PolyAI | Platform by quote; model API 2 cents a connected minute | $100 credit on the model API for sign-ups before November 19 | Managed service, plus a model-only API | SOC 2+ Type 2; HIPAA not stated | No ratings found |
| Synthflow | No public price; annual contract only | None | Visual builder | SOC 2 Type 2 and HIPAA | 4.1 (215 reviews) |
| Bland AI | Start plan: no monthly fee, $0.14 a talk minute | No monthly fee or card on Start | Conversational pathways and API; managed on Enterprise | SOC 2 Type II; HIPAA BAA on Enterprise only | 2.9 (2 reviews) |
| Dapta | $99 a month (Pro) | Free trial (length not stated) | No-code builder | SOC 2 (company claim); HIPAA not stated | 4.9 (153 reviews) |
| Vapi | No monthly fee; $0.05 a minute hosting plus provider costs | $5 in free credits | API-first | SOC 2 Type II; HIPAA add-on at $2,000 a month | 2.5 (13 reviews) |
Test results side by side
No platform ran away with this test. The top three, Retell AI, PolyAI and Synthflow, all scored 3 out of 5, and the whole group sat between 2 and 3. Callers who interrupted or had an accent tripped every agent up at least five times in 20 calls. PolyAI and Synthflow got the most calls right first time, 15 of 20. Retell AI managed 14 but was the most even, and the only platform where 7 of our 10 needed connections worked without code.
Building took a long time everywhere, from 104 minutes on PolyAI to 128 on Dapta and Vapi. Retries mattered: Synthflow rescued 4 of its 5 failed calls. Reply speed was close, from 1.10 seconds on Synthflow to 1.45 seconds on Bland AI, whose alerts were also the weakest at 5 of 10 checks.
Every tool got the same test, between October 20, 2026 to October 26, 2026.
| Tool | Score | Runs completed correctly out of 20 | Time to build each workflow from sign-up | How failures are handled (retries, alerts, human hand-off) | Cost per 100 runs at list prices | Integrations available for the workflow without code |
|---|---|---|---|---|---|---|
| Retell AI | 3/5 | First-pass 14/20 calls correct | 118 min/build; 1 workflow(s) | Retries recovered 4/6; alerts 7/10 | – | 7/10 required connections no-code |
| PolyAI | 3/5 | First-pass 15/20 calls correct | 104 min/build; 1 workflow(s) | Retries recovered 3/5; alerts 7/10 | – | 6/10 required connections no-code |
| Synthflow | 3/5 | First-pass 15/20 calls correct | 115 min/build; 1 workflow(s) | Retries recovered 4/5; alerts 7/10 | – | 6/10 required connections no-code |
| Bland AI | 2.5/5 | First-pass 14/20 calls correct | 118 min/build; 1 workflow(s) | Retries recovered 4/6; alerts 5/10 | – | 6/10 required connections no-code |
| Dapta | 2.5/5 | First-pass 13/20 calls correct | 128 min/build; 1 workflow(s) | Retries recovered 5/7; alerts 7/10 | – | 6/10 required connections no-code |
| Vapi | 2/5 | First-pass 12/20 calls correct | 128 min/build; 1 workflow(s) | Retries recovered 5/8; alerts 6/10 | – | 6/10 required connections no-code |
Retell AI
Best overallRetell AI came first of six with 3 out of 5. It got 14 of our 20 test calls right first time, rescued 4 of the 6 failures on a retry and replied in a median of 1.19 seconds. It was the only platform where 7 of 10 needed connections worked without code, and its alerts met 7 of our 10 checks. Our full Retell AI review has the details.
Retell is a self-serve platform for AI phone agents, with chat and SMS agents in the same place. You build in a drag-and-drop flow canvas or through the API, pick a language model and a voice, and attach a Retell, Twilio or SIP number. Pricing is itemised, so you can see what each choice adds per minute.
Setup was its weak spot at 2.5: building took 118 minutes. Silence and hold time are billed, and unless you opt out of recording, Retell may use de-identified call data to train its models. Users rate it 4.9 out of 5 on Trustpilot from 805 reviews (checked November 2026), on a paid profile that asks customers for reviews.
Who it's for
Small and mid-sized teams that want to build their own phone agent, start without a monthly fee and see what every minute costs.
Skip it if
You want the vendor to build and run the agent for you. PolyAI's managed service fits that better, if you can handle a sales process.
What we liked
- 7 of 10 needed connections worked without code
- No monthly fee, with $10 in free credits
- Failed calls aren't billed, and billing is per second
What we didn't
- 118 minutes to build our booking agent
- Silence and hold time are billed
- Calls may train its models unless you opt out of recording
Key features
- Drag-and-drop flow builder with simulation testing
- Batch outbound calling at $0.005 a dial
- Knowledge base, guardrails and PII removal as add-ons
- Choice of OpenAI, Anthropic and Gemini models
- SOC 2 Type II, HIPAA and ISO 27001
Plans and prices
| Pay as you go Voice engine 0.055 USD per minute; Telephony 0.015 USD per minute (SIP trunking and custom telephony free). | Free |
| Enterprise Volume pricing (no tiers published); Concurrency starting at 50+. | Custom contact sales |
PolyAI
Best for large contact centresPolyAI came second with 3 out of 5. It tied for the most calls right first time, 15 of 20, and was the quickest to build, at 104 minutes. Its alerts met 7 of our 10 checks and it replied in a median of 1.28 seconds. But retries rescued only 3 of its 5 failures, and just 6 of 10 connections worked without code. More in our PolyAI review.
PolyAI builds and runs voice and chat agents for large customer service teams. Enterprise customers design and tune agents in Dialog Studio and Wren, with maintenance and 24/7 support included in the per-minute price. Developers can also use its own voice model, Dialog-RSN-1, for 2 cents per connected minute, without phone lines or call handling.
The catch for smaller buyers is that the main platform is priced by quote only. It lists SOC 2+ Type 2, ISO 27001 and PCI DSS, though its pages describe training on customer data differently. We found no independent user ratings to report.
Who it's for
Large contact centres that want to replace phone menus and would rather the vendor build, maintain and support the agent.
Skip it if
You want to sign up and start today with a visible price. Retell AI is self-serve, has no monthly fee and came first in our test.
What we liked
- 15 of 20 calls right first time
- Quickest build in the test at 104 minutes
- Maintenance and 24/7 support included in the price
What we didn't
- Retries rescued only 3 of 5 failed calls
- No published platform price
- Only 6 of 10 needed connections worked without code
Key features
- Dialog Studio for building agents with flows and tools
- Wren for designing, testing and tuning agents
- Dialog-RSN-1 voice model API
- Test calls and A/B tests at no extra charge
- Use your own phone carrier over SIP at no charge
Plans and prices
| Dialog-RSN-1 API Text tokens per 1M: 2.00 USD input, 0.20 cached input, 5.00 output; Voice output free until 19 Nov. | Custom contact sales |
| Agentic Dialog Platform (Wren, Dialog Studio) Maintenance, improvements and 24/7 support in price; Security, model upgrades, pre-built integrations, test calls, A/B tests, monitoring at no charge. | Custom contact sales |
Synthflow
Best for non-technical teamsSynthflow came third with 3 out of 5. It matched PolyAI with 15 of 20 calls right first time, its retries rescued 4 of 5 failures, the best recovery in the test, and it replied fastest, in a median of 1.10 seconds. Building took 115 minutes and only 6 of 10 connections worked without code. Read our Synthflow review.
Synthflow builds phone agents in a visual Flow Designer, with a Test Center for simulated calls, versions and rollbacks. It runs its own phone lines, also covers chat, SMS and WhatsApp, and connects to HubSpot, Salesforce, Zapier and call centre systems like Five9 and Genesys.
The hard part is buying it. Synthflow sells only through annual enterprise agreements, with no free plan, trial or public price and no self-serve cancellation. On Trustpilot it has 4.1 out of 5 from 215 reviews (checked November 2026), with recent complaints about billing after cancelling.
Who it's for
Non-technical teams at larger companies that want a visual builder and are ready to sign an annual contract.
Skip it if
You want to test on your own calls before you commit. Retell AI has no monthly fee and $10 in free credits to try it.
What we liked
- Retries rescued 4 of 5 failed calls
- Fastest replies at a median of 1.10 seconds
- Voice, chat, SMS and WhatsApp in one place
What we didn't
- No free plan, trial or public price
- Annual contract required for every customer
- No self-serve cancellation
Key features
- Flow Designer with multiple agents
- Test Center with simulated calls and rollbacks
- Human handoff on failed attempts or sentiment
- PII redaction and a 30-day retention limit
- Own phone lines, plus SOC 2 Type 2 and HIPAA
Plans and prices
| Enterprise annual agreement Scoped by volume, concurrency, telephony and number ownership, integrations, security and launch support; White-label terms can be added for BPOs and platforms. | Custom contact sales |
Bland AI
Best for regulated enterprisesBland AI came fourth with 2.5 out of 5. It got 14 of 20 calls right first time and rescued 4 of 6 failures on a retry. But building took 118 minutes, only 6 of 10 connections worked without code, its alerts met just 5 of our 10 checks, the fewest here, and its median reply of 1.45 seconds was the slowest. Our Bland AI review explains the scores.
Bland runs phone agents on its own speech recognition, language and voice models, so it can charge one bundled rate per talk minute and offer self-hosted and on-premises setups. It focuses on regulated calls in healthcare, insurance and finance, says it supports more than 40 languages, and gained FedRAMP 20x Class A in August 2026.
Flexibility was its weakest part at 2. Transfers to a person, extra channels, business associate agreements and single sign-on all need an Enterprise contract, and we found no refund policy. On Trustpilot it has 2.9 out of 5 from just 2 reviews (checked November 2026).
Who it's for
Large, regulated businesses running high-volume calls that need their own hosting and a long list of compliance badges.
Skip it if
You're a small team that wants an easy booking line. Retell AI scored higher, connected more tools without code and has no monthly fee to start.
What we liked
- Retries rescued 4 of 6 failed calls
- Start plan has no monthly fee and needs no card
- Own models in one bundled per-minute rate
What we didn't
- Alerts met only 5 of our 10 checks
- Slowest replies at a median of 1.45 seconds
- Transfers, extra channels and compliance are Enterprise only
Key features
- Conversational pathways for structured calls
- Knowledge bases: 10 on Start, 50 on Build
- More than 40 languages, with mid-call switching
- Self-hosted, private cloud and on-premises options
- SOC 2 Type II, HIPAA, PCI DSS and FedRAMP 20x Class A
Plans and prices
| Start LLM, speech-to-text and text-to-speech included, no token charges; 100 daily and hourly call cap. | Free |
| Build 2,000 daily and 1,000 hourly calls; 50 concurrent calls. | $299 a month |
| Enterprise Unlimited call caps and voices; Warm and live transfers, guardrails, citations, outcomes. | Custom contact sales |
Dapta
Best for WhatsApp sales follow-upDapta came fifth with 2.5 out of 5. It got 13 of 20 calls right first time, but its retries rescued 5 of 7 failures, its alerts met 7 of our 10 checks and it replied in a median of 1.15 seconds. Setup was its weakest part at 2: building took 128 minutes and 6 of 10 connections worked without code. See our Dapta review.
Dapta is a no-code platform for small and mid-sized businesses whose AI agents answer and make calls, text leads and book meetings. It stands out for putting phone calls and WhatsApp calls in one tool, and it connects to HubSpot, GoHighLevel, Salesforce, Google Calendar and Notion.
Plans are monthly credit pools with unlimited agents, from Pro at $99 a month. It claims SOC 2 on its home page, but we found little else about the company. Users rate it 4.9 out of 5 on Trustpilot from 153 reviews (checked November 2026), praising fast support.
Who it's for
Small businesses that follow up sales leads by phone and WhatsApp and want it tied to their CRM without code.
Skip it if
Getting phone calls right is what matters most. Retell AI, PolyAI and Synthflow all got more calls right first time.
What we liked
- Retries rescued 5 of 7 failed calls
- Voice and WhatsApp agents in one tool
- Connects with HubSpot, GoHighLevel and Salesforce
What we didn't
- Only 13 of 20 calls right first time
- 128 minutes to build one agent
- Paid plans start at $99 a month
Key features
- AI voice agent that answers, qualifies and books
- AI calls inside WhatsApp
- dForms for capturing leads
- AI notetaker for meetings
- MCP server and API
Plans and prices
| Pro 100k credits; 5 users. | $99 a month |
| Scale Up 500K credits; Unlimited users. | $499 a month |
| Prime 1.5M credits; 70 workspaces. | $1,499 a month |
Vapi
Best for developersVapi came last of six with 2 out of 5. Only 12 of our 20 calls went right first time, the fewest in the test, and building took 128 minutes. Retries rescued 5 of 8 failures, its alerts met 6 of our 10 checks, and 6 of 10 connections worked without code. Our Vapi review covers the test in full.
Vapi is a developer kit for phone agents. You choose the speech recognition, language model, voice and phone provider, and Vapi runs the live call for $0.05 a minute in hosting, passing provider costs through at cost. Its own calculator puts 1,000 minutes at $82 to $129 a month in total.
There is no visual builder for non-technical staff, which shows in its setup score of 2. Vapi doesn't block incoming calls unless you set limits, and HIPAA needs a $2,000 a month add-on. On Trustpilot it has 2.5 out of 5 from 13 reviews (checked November 2026).
Who it's for
Engineering teams that want to choose every provider and build their own voice product.
Skip it if
You don't have an engineer to set it up. Retell AI also lets you choose models, with a visual builder and better results in our test.
What we liked
- Mix and match speech, model, voice and phone providers
- No monthly fee to start, with $5 in free credits
- Retries rescued 5 of 8 failed calls
What we didn't
- Only 12 of 20 calls right first time
- Real cost per minute is well above the $0.05 hosting fee
- HIPAA add-on costs $2,000 a month
Key features
- Bring your own language model, transcription and voice
- Unlimited agents on every plan
- Simulated test calls and monitoring
- Zero data retention from Core
- Free Vapi SIP, WebSocket and WebRTC transport
Plans and prices
| No Success Package (pay as you go) Vapi hosting 0.05 USD per minute; Deepgram transcriber about 0.0095 to 0.0099 USD per minute. | Free |
| Core 10 concurrent calls; 5 phone numbers. | $29 a month |
| Pro 30 concurrent calls; 10 organizations and 10 phone numbers. | $999 a month |
| Premier Elevated limits; Custom RBAC, zero data retention and SSO. | Custom contact sales |
What it costs to get started
Most of these platforms charge by the minute, so the cheapest way in has no monthly fee. Retell AI lists about $0.07 to $0.31 a minute all in, plus $2 a month per phone number, with $10 in free credits. Bland AI's Start plan is $0.14 a talk minute with no monthly fee, and Build is $299 a month at $0.12 a talk minute. Vapi charges $0.05 a minute for hosting plus provider costs, with $5 in free credits; Core is $29 a month plus usage and Pro starts at $999 a month.
Dapta's plans are $99, $499 and $1,499 a month, billed monthly, and it mentions a free trial. PolyAI's model-only API is 2 cents per connected minute, but its full platform has no public price, and Synthflow sells only by quote on annual contracts. Prices were checked on November 2 and 3, 2026.
| Tool | Cheapest way to start | Free plan | Free trial |
|---|---|---|---|
| Retell AI | Free | Yes | No |
| PolyAI | No public price | No | Yes |
| Synthflow | No public price | No | No |
| Bland AI | $299 a month (Build) | Yes | No |
| Dapta | $99 a month (Pro) | No | Yes |
| Vapi | $29 a month (Core) | Yes | No |
Prices from each tool's own pricing page. Prices can change, so check before you buy.
Also worth knowing about
We didn't test these platforms, but they come up often and may suit a specific need.
Ringly
A phone agent built for online shops, which says on its own site it costs $99 a month for 50 conversations. We haven't tested it.
Voiceflow
An agent builder with voice support that often appears in comparisons. We haven't tested it as a voice agent.
Cognigy (NICE)
Enterprise conversational AI for contact centres. We haven't tested it, but large teams may want it on their shortlist.
How we tested
Every platform went through the same test from October 20 to October 26, 2026. On each one we built the same phone booking agent for a made-up online store, then made 20 scripted test calls in which callers interrupted the agent and spoke with different accents. The full set-up is in how we test.
We counted calls right first time and failures a retry rescued, timed the build from sign-up, checked alerts and hand-off to a person against 10 checks, counted how many of 10 needed connections worked without code, and noted the median reply time.
Each platform then got a score out of 5, in half points, for reliability, ease of setup, flexibility, integrations and value for money. Together they make the overall score, and the ranking follows it.
How to choose
If you have engineers, Vapi lets them choose every part. If your operations team will build it, Retell AI's flow builder connected the most tools without code in our test. If you want the vendor to do it, PolyAI runs a managed service.
A low headline rate often leaves out the voice, model or phone line. Vapi's hosting is $0.05 a minute, but its own calculator shows about $0.08 to $0.13 a minute all in. Bland AI and Retell AI publish fuller per-minute prices.
Retell AI and Vapi give free credits, and Bland AI's Start plan has no monthly fee. Synthflow has no trial and needs an annual contract, so you can't test it on your own calls first.
Check whether the business associate agreement is self-serve or enterprise only. Retell AI lists HIPAA with a signed agreement, Vapi charges $2,000 a month for HIPAA mode, and Bland AI offers it only on Enterprise.
Retell AI may train on de-identified call data unless you opt out of recording, and PolyAI's pages describe training differently. Vapi offers zero data retention from Core, and Synthflow lets you limit retention to 30 days.
Terms you'll see
- Latency
- The pause between a caller finishing speaking and the agent starting to reply.
- Concurrent calls
- How many calls the agent can handle at the same moment.
- BAA
- A business associate agreement, the contract a US company handling health data needs before a vendor can process it.
- SIP trunking
- A way to connect your own phone lines to a voice platform over the internet.
- Speech-to-speech model
- An AI model that listens and replies in audio directly, instead of turning speech into text and back.
- IVR
- The old press-one-for-sales phone menus that many voice agents now replace.
Frequently asked questions
How much do AI voice agents cost?
Most charge by the minute. Retell AI lists about $0.07 to $0.31 a minute all in, Bland AI $0.12 to $0.14 a talk minute, and Vapi $0.05 a minute for hosting plus about $0.03 to $0.08 in provider costs. Dapta starts at $99 a month, billed monthly. Synthflow and PolyAI's full platform are sold by quote only.
Is there a free AI voice agent platform?
Not a fully free one. Retell AI gives $10 in free credits and Vapi $5, and neither charges a monthly fee to start. Bland AI's Start plan has no monthly fee and needs no card, but you pay $0.14 per talk minute. PolyAI offers $100 of credit on its model API for sign-ups before November 19.
Which AI voice agent platform is best for developers?
Vapi and Retell AI are the main self-serve options for developers. Vapi is built API-first and lets engineers choose every provider, but it came last in our test. Retell AI has an API as well as a visual builder, lets you pick from several language models and voices, and came first overall.
Can I use an AI voice agent for cold calls?
The vendors put the legal responsibility on you. Retell AI's terms require documented consent, telling callers they are speaking to AI, Do-Not-Call scrubbing and calling-hour limits, and Vapi points to the TCPA. Bland AI's terms also make the customer responsible for calls. This isn't legal advice, so check the rules where you call before you start.
Do I need HIPAA for a voice agent?
If calls involve health data in the US, you need a signed business associate agreement. Retell AI isn't a business associate unless you sign one. Vapi charges $2,000 a month for HIPAA mode with an agreement, and Bland AI offers agreements only on Enterprise. Synthflow lists HIPAA coverage within its annual contracts.
How did we test these AI voice agents?
From October 20 to October 26, 2026, we built the same phone booking agent on each platform and made 20 scripted test calls with interruptions and different accents. We counted calls right first time and failures rescued by a retry, timed the build, checked alerts and hand-offs, counted connections that worked without code and noted reply speed.
The bottom line
Start with Retell AI if you want to build and test a phone agent yourself, and ask PolyAI for a quote if you'd rather have one built and run for you.
Make your case
Think a tool is missing or wrong?
If you use a tool we reviewed, or work for the company, email us with what you saw. We'll look at the evidence and update the review if it changes our findings.
Think your company belongs on this list?
Send us your product, website and the category it fits. We'll test it the same way as every other tool. It's free, and we can't promise a date or a score.
Liam Foster
If there's a strange new AI tool making its way around the internet, I've probably already bookmarked it. My favorite part is figuring out what these platforms can actually do.
Update history
- November 4, 2026: published with the results of our test, run between October 20, 2026 to October 26, 2026.