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Every endpoint on this page requires either a Clerk-issued JWT (Authorization: Bearer <token>) or an organization API key (x-api-key: pk_…). Anonymous calls return 401 Unauthorized. See Authentication for the full setup.
The agent_id must belong to a voice-enabled agent. The phone_number_id must be a provisioned outbound number in your organization — list them with GET /api/v1/phone-numbers.

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Request

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phone_number_id
string
required
UUID of the outbound phone number to dial from.
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to_phone_number
string
required
Destination number in E.164 format (e.g. +971501234567).
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agent_id
string
required
UUID of the agent that will drive the conversation.
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ttl
integer
default:"100"
Maximum call duration in seconds. The call is force-terminated when this elapses.
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session_variables
object
Free-form key/value map. Every key is available as {{key}} in the system prompt and is echoed back verbatim in webhooks regardless of whether the prompt referenced it. Use this for both prompt context and correlation IDs. See Session variables.

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Code examples

curl -X POST 'https://api.agntix.ai/api/v1/phone-numbers/fba8677f-e464-4362-ba4f-55bbdc3dab94/calls/start' \
  -H "x-api-key: $AGNTIX_API_KEY" \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json' \
  -d '{
    "to_phone_number": "+971501234567",
    "agent_id": "d796c919-7ef3-413a-8bf1-351b6442953a",
    "ttl": 180,
    "session_variables": {
      "customerName": "Alex Morgan",
      "contextSummary": "Order #88291, placed 2026-05-09, status shipped, ETA 2026-05-14",
      "objective": "Confirm delivery slot and capture preferred time",
      "crmContactId": "CRM-7728"
    }
  }'

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Sample response

{
  "sessionId": "4981804c-2658-4893-84ff-9c2fa90fb3c2"
}
The same sessionId flows in session.created / session.ended webhooks and is the path parameter for GET /api/v1/chat/sessions/{sessionId}.
For high-volume outbound calling, use Call Campaigns instead — they manage retries, scheduling, and contact lists automatically.