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The VoiceInfra REST API gives you programmatic control over your AI voice agents. Use it to trigger outbound calls from any external system — whether that’s a CRM, an automation platform, or your own application — and receive structured call data back via webhooks when each call completes. Every request authenticates with an API key, and every response returns JSON.

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Base URL

All API requests target the following base URL: 
https://api.voiceinfra.ai/v1

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Available endpoints

EndpointMethodDescription
/calls/outboundPOSTInitiate an outbound call from an AI agent

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Authentication

Every request to the VoiceInfra API must include your API key in the X-API-Key request header. Requests without a valid key return 401 Unauthorized. 
X-API-Key: YOUR_API_KEY
See the Authentication guide for full details on generating keys, managing multiple keys, and security best practices.

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Request format

All requests must set the Content-Type header to application/json and send a JSON body where applicable. 
Content-Type: application/json

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Response format

All responses return JSON. Successful requests return a 2xx status code with a JSON body. Failed requests return a 4xx or 5xx status code with an error object that describes what went wrong.
Error response
{
  "error": {
    "code": "invalid_agent",
    "message": "The specified agent_id does not exist or is not active."
  }
}

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Common error codes

StatusCodeDescription
400validation_errorMissing or invalid request parameters
401unauthorizedInvalid or missing API key
404not_foundAgent or resource not found
422invalid_phonePhone number not in valid E.164 format
429rate_limitedToo many requests
500server_errorInternal server error

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Rate limits

Standard rate limits apply to all API endpoints. If your integration requires a higher throughput limit, contact VoiceInfra support to discuss your needs.
When you hit a rate limit, the API returns 429 rate_limited. Build exponential backoff into your integration to handle this gracefully.

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Idempotency

Each call to POST /calls/outbound creates a new, unique call_id in the response. Use this identifier to correlate the webhook event you receive when the call completes — every call.completed webhook payload includes the matching call_id.
Store the call_id in your system immediately after initiating a call so you can reliably match incoming webhook events to the original request.

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Explore the API

Authentication

Generate API keys, secure your credentials, and understand authentication errors.

Outbound Calls

Trigger AI-powered outbound calls with dynamic per-call configuration.