AI voice agent platform, built by describing it.
Most voice AI platforms start with an API, dashboard, or flow builder. Callable starts with a plain-language brief: describe the line; the builder drafts, tests, and publishes it.
Four ways platforms make you build a voice agent.
Platforms in this category start on one of these paths.
API-first, in code
Vapi gives developers an API and SDKs for wiring language models, speech providers, and call logic together, then deploys it through its own infrastructure.
Dashboard flows
Retell AI is built around a dashboard for configuring phone agents, with API access for teams that want custom integration.
Node-based pathways
Bland AI's assistant Norm drafts a node-based Pathway from a prompt, editable on its own visual canvas.
Describe it, test it, publish it
Callable starts with a plain-language brief. The builder drafts the line, tests it in scripted conversations, then you publish it to a number you own.
How the four compare.
Six differences from what every platform publishes.
| Aspect | Callable | Vapi | Retell AI | Bland AI |
|---|---|---|---|---|
| How you build it | Describe the line in plain language. The builder asks what it can't infer and drafts it. | Configured through Vapi's API and SDKs, in code. | Built through Retell AI's dashboard, with API access for custom integration. | Bland AI's assistant Norm drafts a node-based Pathway from a prompt, editable on its own visual canvas. |
| Where it runs | Your own phone number, on its own dedicated server. | Vapi's own container hosting for deployed agents; its Scale tier adds a fixed platform fee under an annual contract. | Retell AI's cloud dashboard, with an on-premises option for enterprise. | Bland AI's platform, with self-hosted and on-premises options. |
| Cost visibility | Every call has an itemized receipt: carrier, transcription, model, and voice, each with its source and rate. | Vapi's own hosting is $0.05 a minute; model, speech, and telephony are billed separately by their own providers, and the Build tier adds $10 per concurrent line each month past the first ten. | Retell publishes $0.07–$0.31 a minute for voice agents — its own voice infrastructure, plus speech, model, and telephony components. | A per-minute rate bundling model, speech-to-text, and text-to-speech ($0.11–$0.14 depending on plan); telephony and human-transfer time are billed separately. |
| Testing before live | Drafts run through scripted test conversations before publishing. | Evals check a single decision point in a fixed conversation; Simulations run a full AI-tester conversation in chat or voice, per Vapi's current docs. | A live demo and free trial, per Retell AI's own site. | Scenario testing before launch, per Bland AI's own site. |
| Providers | OpenAI, Gemini, or Grok to decide what to say; Soniox or Deepgram to hear the caller; Cartesia, ElevenLabs, or Inworld to speak the reply; Twilio or Telnyx to carry the call. | — | — | — |
| Number | Buy a number in the dashboard; once it's bought, it's yours the same way any other number you add there is. | — | — | — |
Straight answers about AI voice agents.
Six questions people ask before picking one.
A platform that answers phone calls with an AI agent instead of a person. Some hand you an API to wire up yourself, some give you a dashboard or a visual builder. Callable starts with a plain-language brief: describe the line; the builder drafts, tests, and publishes it to a number you own.
It depends on the platform. Vapi is API-first and needs code and SDK integration; Retell AI is dashboard-first with optional API access; Bland AI is built through a visual builder. Callable needs none — describe the line, review the draft, then publish.
Callable's own provider list, per line: OpenAI, Gemini, or Grok to decide what to say; Soniox or Deepgram to hear the caller; Cartesia, ElevenLabs, or Inworld to speak the reply; Twilio or Telnyx to carry the call. The builder sets a default stack; any of the four can be swapped.
On its own dedicated server, shared with no other Callable. Other platforms in this comparison run inside their own hosting, a cloud dashboard, or an on-premises option, depending on which one you pick.
Before a draft can publish, it runs six graded caller scenarios as text conversations — including scenarios built to try to break it — through the same path the builder's own playground uses, and every transcript is graded. Publishing is a separate, deliberate step: nothing goes live until you press publish.
About $0.062 a minute on the default stack, at the providers’ published rates, itemized by layer on every call: carrier, transcription, model, voice — see /cost. Other platforms publish their own rates differently: a flat per-minute hosting fee, a published range, or a bundled rate before telephony.
About $0.062 a minute on the default stack, at the providers’ published rates, itemized by layer on every call: carrier, transcription, model, voice. See the price book →
Describe the line you need.