Visibility in this ranking can be paid for. Payment moves a vendor's position within the
shortlist; it never adds a vendor, and it never changes a word of the review. The largest vendors in AI voice agent platforms
cannot hold places 1 to 3. Places 1 to 3 go to challengers, vendors outside the best-known brands in a category,
wherever the category has them; the established names follow from place 4 in their ranked order. How it works: placement disclosure ·
editorial process.
The 11 tools, reviewed
#1 Retell AI
Pay-as-you-go phone agents for developers and operators · United States · retellai.com
Phone agents Pay as you go Call analytics
Retell publishes one range, $0.07 to $0.31 per minute, and says plainly that it does not ask for an annual contract before you write any code. The free credit is $10, the concurrency allowance is 20 calls, and the feature list reads like a receptionist's job description: transfer to a person, book into a calendar, work through a keypad menu, run outbound batches, show a branded caller ID.
- Pricing: Usage-based / minute. Pay as you go at $0.07 to $0.31 per minute for voice agents depending on model and voice, $10 in free credits, enterprise on request. Free plan: free trial.
- Best for: Teams launching a first phone agent
- Strengths: Call transfer to humans; Appointment booking; Knowledge base.
Where it falls short
The headline rate moves with the language model and voice you pick, so the budget is a range until you test your own script.
Wrong for
A contact center that needs a named delivery team and a negotiated compliance package from day one.
Visit Retell AI →
#2 Vapi
Developer API for building and running voice agents · United States · vapi.ai
Developer API Bring your own models Telephony
Vapi is the platform for teams that want to choose the transcriber, the language model and the voice themselves and see each line on the bill. Its pricing page lets you pick a provider for each layer and shows the sum: a 1,000-minute month comes to roughly $82 to $129 in the example it prints.
- Pricing: Usage-based + success package. Pay by usage with $5 in free credits; success packages from $29 per month (Core) and $999 per month (Pro); provider costs passed through without markup. Free plan: free trial.
- Best for: Engineering teams that want to pick every model
- Strengths: Full model catalog; Provider pass-through pricing; Unlimited agents.
Where it falls short
The bill has four parts (hosting fee, transcription, model, voice) plus carrier charges, so forecasting takes a spreadsheet. Concurrency starts at four calls on the usage-only tier, extra lines cost $10 each per month, and the HIPAA-eligible handling is a $2,000 per month add-on.
Wrong for
A business owner who wants to answer the phone this week without touching an API.
Visit Vapi →
#3 Goodcall
AI phone answering billed per unique caller · United States · goodcall.com
Small business Answering Flat plans
Goodcall counts one thing, how many different phone numbers its agent helped in a month, and ignores minutes entirely. Starter is $79 for 100 customers, the vendor estimates about 150 calls, and a nine-minute booking costs what a wrong number costs. A local number is included, you can forward your own, and you describe changes in plain English to its builder.
- Pricing: Per unique customer / month. Starter $79 a month for 100 unique customers, Growth $129 for 500, Scale $299 for 2,000, with overage per customer; a local number is included. Free plan: free trial.
- Best for: Owner-run local businesses missing calls
- Strengths: Local number included; Unique-customer billing; Specialist workers.
Where it falls short
The plans cap workers (5 on Starter), external tools (1 on Starter) and call history (30 days), so a business with several systems outgrows it quickly. There is no phone-system engineering underneath for call centers, and a franchise group must contact sales.
Wrong for
A call center with thousands of calls from the same repeat customers or a team that needs programmable telephony.
Visit Goodcall →
#4 LiveKit
Open-source realtime stack for voice and video agents · United States · livekit.io
Open source Realtime Self-hostable
LiveKit is the only entry here whose agent framework is published under an open-source licence, Apache-2.0, on GitHub, which means the code that runs your agent does not depend on a contract. The hosted cloud adds deployment, observability, simulations, one free phone number and inference credits on a free Build plan, then $50 and $500 monthly tiers.
- Pricing: Plan + usage / minute. Free Build plan; Ship from $50 a month; Scale from $500 a month; Enterprise on request; example agent minute about $0.048 in its calculator. Free plan: open source.
- Best for: Developers who want code they can self-host
- Strengths: Agents framework (Apache-2.0); Agent deployment; Observability.
Where it falls short
It is a toolkit, not a finished receptionist: nobody gets a scheduling flow, a script editor for non-developers or a reporting dashboard for managers out of the box.
Wrong for
A business with no engineer, or a team that wants a vendor to own call quality.
Visit LiveKit →
#5 Bland AI
Enterprise phone agents on its own model stack · United States · bland.ai
Phone agents Own models Regulated calls
Bland folds the language model, transcription and voice into a single per-minute figure: $0.14 on the Start plan with no platform fee, $0.12 on Build with a $299 monthly fee. The company says it runs its own models end to end instead of stitching vendors together, and targets healthcare, insurance and financial calls.
- Pricing: Per minute (all-in). Start plan $0.14 per minute with no platform fee; Build $0.12 per minute plus $299 a month; Enterprise custom; telephony billed separately. Free plan: free trial.
- Best for: Regulated teams automating high-stakes calls
- Strengths: Conversational Pathways; Single per-minute rate; Knowledge bases.
Where it falls short
Warm transfers, guardrails, alarms, outcomes, SSO and BAA are listed as Enterprise only, and a team that needs them is in a sales conversation. Telephony is billed outside the rate.
Wrong for
A developer who wants to swap the model or voice provider per call.
Visit Bland AI →
#6 Synthflow
Enterprise voice agent platform with a flow designer · Germany · synthflow.ai
Flow designer Own telephony Enterprise
Synthflow states its entry price outright, enterprise contracts from $30,000 a year, then scopes the rest around calls, concurrency and security review. In return you get a visual flow designer where subflows act as separate agents, a test center that runs simulated calls before launch, its own telephony and an automatic quality layer.
- Pricing: Annual contract. Enterprise contracts start at $30,000 annually, scoped by volume, concurrency, telephony and security needs; no self-serve price in the page we fetched. Free plan: none.
- Best for: Mid-size firms wanting a managed rollout
- Strengths: Visual Flow Designer; Subflows as agents; Test Center simulations.
Where it falls short
A $30,000 floor excludes the small teams that other entries serve, and the page we fetched shows no self-serve plan or free tier. Figures such as 65 million calls a month are the vendor's own claim. Switching away means rebuilding flows in another builder.
Wrong for
A shop with a few hundred calls a month.
Visit Synthflow →
#7 Voiceflow
Collaborative design platform for voice and chat agents · Canada · voiceflow.com
Agent design Voice and chat Agencies
Voiceflow is a design environment first: conversation flows, knowledge and tools are assembled on a canvas that several people can edit, then deployed to voice and chat. It offers the major language models or your own, lists SOC 2, ISO 27001, GDPR and HIPAA on its security line, and gives agencies multi-client workspaces with white-labeling. Its terms name Voiceflow, Inc. at a Toronto address.
- Pricing: Usage-based / quote. Free trial without a card and usage-based billing for agencies; business pricing is by request, and no figures appear in the page we fetched. Free plan: free trial.
- Best for: CX teams and agencies designing agents together
- Strengths: Visual agent builder; Voice and chat channels; Choice of model providers.
Where it falls short
The pricing page we fetched states no rates for businesses, so the cost of a voice deployment cannot be estimated without a call to sales.
Wrong for
A shop that wants a number answered tonight with a flat price.
Visit Voiceflow →
#8 PolyAI
Enterprise voice assistants for customer service lines · United Kingdom · poly.ai
Enterprise Managed service Contact center
PolyAI sells outcomes for a customer service line, and its pricing page says ongoing use is charged per minute with improvement, maintenance and 24/7 support included. It publishes its own research models and offers Dialog Studio, a developer kit, platform and model APIs, and named vertical pages for hotels, restaurants, insurers and utilities.
- Pricing: Per minute / quote. Priced per minute of ongoing use, including improvements, maintenance and 24/7 support; no rate is published, contact sales. Free plan: none.
- Best for: Large service lines that want a managed build
- Strengths: Dialog Studio; Wren agent builder; Dialog-RSN-1 model.
Where it falls short
No price is visible, so comparing it with a metered tool means a sales cycle. The service model assumes a sizeable and steady call volume; a small team gets little from a managed build.
Wrong for
A business that wants to start on a card this afternoon.
Visit PolyAI →
#9 Parloa
Agent management platform for enterprise customer service · Germany · parloa.com
Enterprise Multilingual Testing
Parloa frames the problem as managing a fleet of agents. Its Performance Lab simulates every change before it ships, Parloa Lens watches production calls, and the vendor picks and tunes the language model, carrying the token cost so the rate stays steady. It claims voice coverage in over 140 languages and names SAP as a partner.
- Pricing: Per minute / per interaction. Consumption-based, per minute for voice and per interaction for chat, built into custom volume packages; outcome-based pricing possible; rates unpublished. Free plan: none.
- Best for: Enterprises scaling agents across countries
- Strengths: Agent Builder; Performance Lab simulation; Parloa Lens monitoring.
Where it falls short
The pricing page explains the model but gives no number, and plans are built around your deployment after an assessment of your contact center. It is a poor fit under a few thousand calls a day.
Wrong for
A single-location business or a developer prototype.
Visit Parloa →
#10 Replicant
Contact-center voice agents with rule-based guardrails · United States · replicant.com
Contact center Guardrails Conversation analytics
Replicant's argument is that an agent should follow the process on the first call and the ten-thousandth, so it combines language models with code-based guardrails and supervisory agents. It runs its own telephony, claims uptime above 99.95%, scores every conversation across channels and lets your team change wording in natural language after launch. Case studies on its site cover roadside, insurance and delivery lines.
- Pricing: Quote only. Not published in the pages we fetched; sold by demo request with delivery support. Free plan: none.
- Best for: Contact centers resolving repeat call types
- Strengths: Deterministic guardrails; Model orchestration; Supervisory agents.
Where it falls short
No price or self-serve option appeared in the pages we fetched, and the terms page we read dates from 2019. Uptime and resolution figures are the vendor's. A smaller business pays for analytics and guardrails it may not use.
Wrong for
A team with fewer than a few thousand calls a month or one that wants to experiment cheaply.
Visit Replicant →
#11 Cresta
AI suite for contact-center agents and analytics · United States · cresta.com
Contact center Agent assist Analytics
Cresta is broader than a phone bot. Its AI Agent automates conversations, Agentic Assist coaches human agents live, Conversation Intelligence analyzes calls, and a newer Deputy Agent handles longer back-office tasks. Its site shows airlines, insurers and telecoms among customers, and its terms name Cresta Intelligence Inc. with offices in Sunnyvale, Toronto, Berlin and Madrid.
- Pricing: Quote only. Not published in the pages we fetched; sold by demo request. Free plan: none.
- Best for: Large contact centers mixing human and AI
- Strengths: AI Agent; Agentic Assist; Conversation Intelligence.
Where it falls short
Pricing is entirely behind a demo. Buying the voice agent alone is not the main route, so a team that wants only an autonomous phone line pays for a suite it will not use. Result figures on its case-study pages are the vendor's own selections.
Wrong for
A small team or developer who wants a phone agent only.
Visit Cresta →
Questions and answers
What is the best AI voice agent platform in 2026?
Retell AI ranks first of 11, best for teams launching a first phone agent. Vapi is second (engineering teams that want to pick every model) and Goodcall third (owner-run local businesses missing calls). Places 1 to 3 go to challengers, vendors outside the best-known brands, wherever the category has them.
How much does an AI phone agent cost per minute?
It depends on what the rate includes.
Can a small business use a voice agent without a developer?
Yes, with the right product. Goodcall includes a local number, builds the agent from a plain description and charges $79 a month for 100 unique customers. Voiceflow offers a visual builder but needs someone to design flows.
Why does Goodcall bill per customer instead of per minute?
Goodcall counts one phone number once a month as a unique customer, so a nine-minute booking and a thirty-second wrong number cost the same, and spam does not count.
Which voice agent platforms are open source?
LiveKit publishes its Agents framework under the Apache-2.0 licence on GitHub, and you can run it yourself or use the hosted cloud, which has a free Build plan.
Do these platforms handle regulated calls such as healthcare?
Some do, at a price. Vapi offers HIPAA-eligible data handling with a business associate agreement for $2,000 a month. Bland lists BAA, SSO and data residency as Enterprise features.
What is the difference between Vapi and Retell AI?
Both are pay-per-minute developer-friendly platforms. Vapi lets you choose the transcriber, model and voice, and bills each layer at provider rates beside a hosting fee, so the control is finer but the invoice has more lines.
Which vendors publish no prices?
Voiceflow for businesses, PolyAI, Parloa, Replicant and Cresta did not show a rate in the pages we fetched, and Synthflow shows only a $30,000 annual contract floor.
Can the agent transfer a caller to a human?
Yes at most vendors, but the tier matters. Retell lists call transfer between human and AI as a standard feature, Goodcall hands off to a person, and Bland lists warm and live transfers among features on its upper tiers.
How do I move from one voice agent platform to another?
Keep the parts you own: the prompt, the tool definitions, the knowledge documents, test calls and your phone number.
Is a voice agent the same as a text-to-speech tool?
No. A text-to-speech product turns written text into audio and has no part in a live conversation.
