15 Best AI Voice Agent Platforms

Retell suits teams that want a working agent quickly and it is developer-friendly. You can start from a template, have its Conductor assistant generate an agent from your website, or write a single prompt.

Testing Retell

I chose a single prompt and had the agent ready to test in a few minutes. The builder shows estimated cost and latency above the prompt, which makes it easier to weigh model and voice choices before you make a call.

Its Test LLM tab runs a text conversation at $0.0208 per message. Maya handled all four turns, and even turned Monday into a specific date, November 9. That date was right.

Maya sounded very natural on a browser call. She gave the same date and hung up by herself after I said goodbye. That 30-second call cost $0.09, while the builder’s $0.134 per minute would suggest about $0.07, so compare a few real calls against the estimate before you budget.

Average latency was 1,228 ms, close to the top of the estimated range, with one reply at 789 ms and another at 1,668 ms.

Our take: Retell is where I’d start if you’re unsure how technical you need to go. A single-prompt agent is quick to build, and conversational flows are there when you need tighter control.

Standout features:

• Single-prompt and conversational flow agents
• Live cost and latency estimates in the builder
• Text tests and AI-simulated conversations
• Post-call extraction, webhooks, and quality monitoring

Vapi gives developers control of every layer. You pick the transcriber, model, and voice separately, pay Vapi for hosting, and pay the model providers at cost.

Testing Vapi

The assistant page breaks cost and latency down by layer. My default setup combined Soniox, GPT-4.1, and a Vapi voice for about $0.09 per minute and 1,530 ms, and presets like Ultra Fast and Cost Saver let you compare trade-offs in one click.

Publishing agent is more careful. A new version opens a review of what changed, then lets you send all, some, or none of your traffic to it, which is useful for trying a new prompt on a small share of calls.

Text chat asks for a card on file even if you have free credits, but a browser call worked without one. The voice was decent, and Maya stayed away from the ibuprofen question and offered the front desk.

The call log is the best of the four. My 45-second call cost $0.05, with Vapi’s platform fee making up about 82% of it, and each reply is split by layer. Turns averaged 1,147 ms, faster than the 1,530 ms the assistant page estimated.

Our take: Choose Vapi if you have engineers and want control over each part of the stack. Non-developers will find Retell or ElevenLabs easier.

Standout features:

• Separate choice of transcriber, model, and voice
• Presets for balance, intelligence, speed, and cost
• Version publishing with traffic splitting
• Evals, simulations, and call logs

Aircall has been a phone system for a decade, and its AI agents resides on that same network. That means no SIP trunks, call forwarding, or separate carrier bills, and the AI can hand a call to your team inside the same system.

The agents cover inbound calls, outbound calls, SMS, and WhatsApp. An outbound agent can call when a lead arrives, a payment comes due, or an appointment approaches, and it can update your CRM, create tickets, and book meetings along the way.

US and Canadian accounts can try four pre-built agents from the browser or phone without setup.

Our take: Aircall makes the most sense if you want AI and human agents in one phone system with one bill. It isn’t the cheapest per minute, but the rate includes the model, voice, and telephony.

Standout features:

• Inbound and outbound voice agents, plus SMS and WhatsApp messaging agents
• 38 languages and numbers in 100+ countries
• 250+ integrations, including HubSpot, Salesforce, and Zendesk
• Performance tracking for resolution rate, CX score, and transfer rate

ElevenLabs started in AI voices, and that remains the main reason to look here. Its agent platform adds workflows, a knowledge base, multilingual support, and a choice of language models.

Testing ElevenLabs

The template gallery is the most visual of the four I tried, with ready agents for support, lead qualification, renewals, and appointment setting. Selecting one shows its full workflow, so you can see the branching logic before you commit.

A blank agent needed only the prompt and first message. Maya passed the text test, though a text chat there starts with your first message, so her opening line never appeared. It came through on a browser call, where she sounded very natural and asked me to confirm the move to Monday before treating it as done.

That 30-second call used 202 credits. The log times each reply by layer, and the model was the part that varied most, from 130 to 798 ms, while voice output stayed under 120 ms.

Our take: ElevenLabs is the easiest place to start for free, and a strong pick where the voice itself matters. Remember that phone charges from your provider is outside its prices.

Standout features:

• Template gallery with visual workflows
• Choice of voices, languages, and language models
• Mock tools for testing without live systems
• Realtime and custom voice modes

Bland focuses on calls at volume, with flat per-minute pricing that doesn’t ask you to add up model and voice costs. Pathways let you script conversations as a visual flow when a single prompt isn’t strict enough.

Looking Inside Bland

Bland puts unusual detail into how the agent sounds. You can set how easily callers interrupt, how often the agent says mm-hm, whether it reacts to what it hears, and even add office or coffee shop noise behind the voice.

Maya passed the text test here too. One setting to review is the system prompt, as a new agent starts with a template full of bracketed placeholders that you need to replace.

The browser call was rougher. Replies felt a bit slower than on the other three, and Maya restarted her greeting from the top each time I spoke over her, so it took three attempts before she finished it. The 31 seconds used 0.07 credits, in line with the $0.14 per minute rate. Call recording was off on this agent, which left a transcript but no audio to replay, so switch it on before you test.

Our take: Bland suits teams planning a lot of outbound calling who like simple billing. Check the Start plan’s limit of 100 calls a day, since a real campaign will quickly need Build plan.

Standout features:

• Flat per-minute pricing
• Pathways for scripted conversations
• Interruption, backchannel, and background noise controls
• Babel mode for automatically switching languages

PolyAI builds agents for large companies with heavy call volumes, on its own dialog models. Its latest, Dialog-RSN-1, works directly on call audio, and the company reports response times under 300 ms.

Agent Studio covers flows, tools, and brand voice from no-code to full code, and agents connect to systems like Zendesk, NICE, and Twilio. PolyAI’s customer stories include one with 1 million calls handled a month.

Our take: PolyAI is worth a conversation if phone support is a major cost and you want a vendor involved in the build. Smaller teams will get going faster elsewhere.

Standout features:

• Proprietary audio-native dialog models
• Agent Studio, from no-code to full code
• Same agents across voice, chat, SMS, and messaging
• Prebuilt integrations and open APIs

Parloa manages the whole life of an AI agent across voice and chat, from design to orchestration and improvement. The people closest to customers can build agents themselves through a low-code interface.

Our take: Parloa fits enterprises that want service teams to own their agents. Its per-minute rates vary by use case, so get quotes for your specific call types.

Standout features:

• Agent lifecycle management on one platform
• Low-code building for non-specialists
• Consumption-based pricing for voice and chat
• SAP solution extension

Synthflow is sold only through annual enterprise agreements. It runs on its own telephony, and it can also connect through SIP or approved enterprise systems.

Its process follows four stages. You design in a visual flow builder, test with simulated calls in the Test Center, launch on its network, and monitor with Auto-QA. Batteries Plus runs its agents inside Zoom Phone across more than 700 US locations.

Our take: Synthflow suits mid-market and enterprise teams that want a structured rollout with engineers helping. Anyone wanting to test first should use Retell or ElevenLabs, as Synthflow has no free plan or trial.

Standout features:

• Visual Flow Designer with multi-agent routing
• Test Center for simulated calls
• Auto-QA and live monitoring
• In-house telephony, SIP trunking, and contact center connections

Deepgram began in speech recognition, and its Voice Agent API now combines speech-to-text, a language model, and text-to-speech behind one WebSocket. Turn-taking, interruptions, and conversation state are handled inside the API.

You can bring your own model or voices for a lower rate, change the agent mid-conversation, and fall back automatically if a model or voice provider fails. Endpoints are available globally and in the EU, India, and Australia.

Our take: Deepgram is recommended for developers who want one vendor for the speech stack without building turn detection themselves. There’s no visual builder to lean on, so you’ll need someone with technical expertise.

Standout features:

• One API for speech, model, and voice
• Built-in end-of-turn and interruption handling
• Bring your own LLM or text-to-speech
• Regional endpoints for data requirements

Telnyx is a licensed carrier in more than 45 countries that also runs speech and language models on its own GPUs. Since calls and AI sit on one network, it reports response times under 200 ms and sends everything on one invoice.

Its voice engine rate covers orchestration, speech-to-text, and text-to-speech. Telnyx estimates a production agent lands near $0.06 per minute once you add its hosted model and carrier minutes, among the lowest figures on this list.

Outbound teams should also note its A-level STIR/SHAKEN attestation, which helps eligible US calls present as trusted. If you only need programmable calling, see our voice call API guide.

Our take: Telnyx is the one to price if per-minute cost at volume decides the deal and you have developers to build with.

Standout features:

• Licensed carrier in 45+ countries
• 1,400+ voices and 80+ languages
• OpenAI-compatible endpoints
• End-to-end tracing and latency breakdowns