9 Best AI Voice Agent Platforms of 2026

Retell AI fits the way agencies work: you sign up, get $10 in credits and 20 concurrent calls, and pay only for minutes with no annual contract. The pricing page lists $0.07 to $0.31 per minute for voice agents and its calculator breaks a call into LLM cost, a $0.055 voice infrastructure fee, text-to-speech and telephony, so you can quote a client a real number before you build. Agents are designed on a drag-and-drop canvas with functions, call transfers, DTMF and SMS steps, and the platform adds outbound campaigns with pacing and retries, IVR navigation and live call takeover. Voices come from several providers, including ElevenLabs, Cartesia, OpenAI and Inworld, and calls can run on Retell, Twilio or Telnyx numbers or your own SIP trunk at no extra charge. Retell lists HIPAA, SOC 2 Type II, GDPR and ISO 27001 compliance. The limits: premium models push the rate toward the top of the range, and contract terms, SSO and dedicated support are Enterprise items.

ElevenLabs sells its agent platform as monthly plans with minutes included rather than pure metering. The free plan gives 15 call minutes and 4 concurrent calls, Starter costs $6 a month for 75 minutes, Creator $22 for 275, and Pro $99 for 1,238 minutes with 20 concurrent calls; extra minutes are $0.08, and the LLM and telephony are billed at cost on top. The builder covers system prompts, knowledge bases, workflows and tools, and the same agent can answer phone calls, web chat, WhatsApp, SMS and email without losing context. Guardrails, simulations and automated tests help you check an agent before a client hears it, and analytics track success rate and CSAT. The voice catalog is the main reason many teams start here. For an agency billing per minute, the included-minute plans are simple to resell, but low concurrency on cheaper tiers and Enterprise-only BAAs limit it for busy or regulated lines.

Vapi is built for developers who want to assemble their own stack. You pay a pre-paid $0.05 per minute hosting fee, and transcription, LLM and voice providers are passed through at cost from a full model catalog. The pricing calculator shows the effect: at 1,000 minutes with Deepgram, OpenAI and ElevenLabs the estimate is $82 to $129 a month. Usage-only accounts get $5 in credits, one phone number and 4 concurrent calls; the $29 Core package raises that to 10 calls and five numbers, and extra lines cost $10 each per month. The developer tooling is the strongest in this list: a CLI, config as code with assistants and tests in git, simulations, and Squads that hand a caller between specialized assistants with context. Vapi telephony, SIP, WebSockets and WebRTC transport are free, with Twilio, Vonage and Telnyx billed by the carrier. The trade-off is setup effort and HIPAA at $2,000 a month.

Telnyx is a telecom carrier, and its voice AI offer is priced like one. The voice engine costs $0.05 per minute and includes orchestration, hosted speech-to-text and text-to-speech; LLM tokens are billed at Telnyx GPU rates (the page puts its Kimi model at about $0.006 per minute) or at Anthropic and OpenAI rates, and telephony starts at $0.0032 per minute. Telnyx estimates a production agent at about $0.06 per minute all in. Pay as you go allows 500 concurrent calls, far more than other self-serve plans here, and US numbers cost $1 a month. Agents can use 1,300+ voices through the TTS router and connect to 30+ pre-built integrations. For agencies, the appeal is one vendor for numbers, SMS and the agent. Two caveats: the voice engine rounds each call up to 60 seconds, which raises the cost of short calls, and the builder is more developer-oriented than the dashboards of Retell or ElevenLabs.

Bland takes the opposite approach to Vapi: instead of passing through each provider, it quotes one per-minute rate that covers the language model, speech-to-text and text-to-speech, with no token charges. The Start plan costs $0.14 per minute with no platform fee and no card, and includes 10 concurrent calls, 100 calls a day and 10 knowledge bases. Build lowers the rate to $0.12 per minute for a $299 monthly fee and raises limits to 50 concurrent calls and 2,000 calls a day. The pricing page says telephony is billed separately, on your own carrier or Bland's Twilio at cost, and that bring-your-own-telephony customers pay no transfer fees. Bland runs its own models and infrastructure and lists SOC 2 Type II, HIPAA with a BAA, ISO 27001 and FedRAMP 20x Class A. The simple rate is easy to resell, but at $0.14 it costs more than a lean Vapi or Telnyx stack, and the daily call cap on Start limits outbound work.

Cartesia is best known for its Sonic voice models, and its managed agents are the cheapest per minute here. The pricing page lists agent call time at $0.03 per minute, down from $0.06, with LLM usage billed separately and $0.014 per minute for calls on a Cartesia-provided number. Plans are small: Free includes $1 of agent usage a month, Pro costs $5 with $5 of prepaid agent usage and 100K speech credits, Startup $49 and Scale $299, each with prepaid agent usage equal to the plan price. Concurrency steps from 8 to 12, 20 and 60 calls across tiers, and included phone numbers rise from 1 to 10. Instant voice cloning starts on Pro and pro cloning on Startup. For a developer testing a phone agent or an agency running a few low-volume lines, the entry cost is hard to beat. The platform is thinner than Retell or Bland on campaigns, transfers and visual flow tools.

Ultravox builds its own speech model rather than chaining separate transcription and LLM steps, and publishes the weights on Hugging Face. Its pricing is the plainest here: the first 30 minutes are free, then $0.05 per minute with text-to-speech included, SIP at half a cent per minute, and no surge pricing. Pay as you go allows 5 concurrent calls, one custom voice and two RAG corpora; Pro, at $100 a month on the annual rate, removes the hard concurrency cap and adds an outbound call scheduler, five voices and 20 corpora. Developers work through REST APIs and SDKs for web and mobile, with built-in links to major telephony providers. The UltraVAD model handles turn-taking. Ultravox has been acquired by Inworld, which the site says will speed up its speech-to-speech work, but buyers should watch for plan changes. The low concurrency cap makes pay as you go a test tier for anything beyond small lines.

Deepgram's Voice Agent API is infrastructure rather than a dashboard. One WebSocket takes audio in and returns audio out, while Deepgram runs speech-to-text, LLM orchestration, text-to-speech, barge-in and function calling. Pricing is per minute of connection time: $0.075 per minute covers its STT, a managed LLM and TTS, bringing your own LLM or voice drops it to as low as $0.050, and an Advanced tier costs $0.163. New accounts get $200 in free credit with no expiry. Flux turn detection ends a turn in about 260 ms, every turn returns a latency breakdown, and automatic fallback keeps a model failure from ending the call. You can self-host on Kubernetes or pick Global, EU, India or Australia endpoints, and agents understand 60+ languages. Deepgram says over 1,000 organizations have built on the API. The catch for agencies is that there are no numbers, campaigns or visual builder, so you supply telephony and the app logic.

PolyAI sells two things. Its main platform is a managed voice agent for large contact centers, priced per minute by quote, with performance improvements, maintenance and 24/7 support folded into that rate. Separately, the Dialog-RSN-1 API gives developers PolyAI's dialog model for 2 cents per connected minute, billed per second, and new accounts get $100 in credit for a limited time. The pricing page lists SIP connections to your own carrier at no charge, pre-built connectors or any API and MCP server, voice, chat and messaging on the same agents, and test calls, simulations and A/B tests on live traffic at no extra cost. Infrastructure is SOC 2 and ISO 27001 certified. For an enterprise replacing a phone tree, the managed model removes a lot of work. For agencies and small developers, the platform price is not published, and the 2 cent API is one component, not a ready phone agent.