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Overview

Agent calling lets external AI agents (Claude, GPT, n8n, Make, custom bots) make phone calls by sending a short natural language prompt. CallCow generates a call workflow from the prompt, makes the call, and delivers results to a callback URL. No workflow setup needed. One API call does everything.

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Setup

1

Create a CallCow account

Sign up at callcow.ai and complete onboarding.
2

Connect a phone number

Go to Settings > Phone Numbers and add a phone number. This is the number your AI agent will call from.
3

Generate an API key

Go to Settings > API Keys and click Create API Key. Copy the key immediately — it starts with ck_live_ and is only shown once.

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Making a call

Send a POST request to /api/call-prompt with your prompt and the recipient’s phone number: 
curl -X POST https://www.callcow.ai/api/call-prompt \
  -H "Authorization: Bearer ck_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "Book a dinner reservation for Friday at 7pm, party of 2, under Josh",
    "recipient_phone": "+14155551234"
  }'
The API returns a workflow_id and call_id: 
{
  "success": true,
  "workflow_id": "abc-123",
  "call_id": "def-456"
}
The AI agent introduces itself as an AI assistant at the start of every call.

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Writing good prompts

Write prompts like you’re briefing a human assistant. Include all the details they’d need.

Good prompts

  • “Book a dinner reservation at Olive Garden for Friday 7pm, party of 2, under Josh Miller” - “Confirm Sarah Johnson’s 3pm appointment tomorrow at Dr. Smith’s office” - “Ask about store hours and if they have size 10 Nike Air Max in stock”

Bad prompts

  • “Make a call” (too vague) - “Book something” (no details) - “Call them” (who? about what?)
Tip: Include who, what, when, where, and any specific details.

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Getting call results

Add a callback_url to your request to receive results when the call ends: 
curl -X POST https://www.callcow.ai/api/call-prompt \
  -H "Authorization: Bearer ck_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "Book a reservation for Friday 7pm, party of 2",
    "recipient_phone": "+14155551234",
    "callback_url": "https://your-server.com/callback",
    "callback_secret": "my-secret-token"
  }'
CallCow will POST results to your URL when the call completes or fails: 
{
  "call_id": "def-456",
  "workflow_id": "abc-123",
  "call_status": "success",
  "provider_status": "completed",
  "call_summary": "Successfully booked a reservation for Friday 7pm, party of 2.",
  "messages": [],
  "form_fills": [],
  "created_at": "2026-03-30T12:00:00.000Z"
}
If you provided callback_secret, the request includes Authorization: Bearer my-secret-token so you can verify it came from CallCow.

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Call statuses

call_statusprovider_statusWhat happened
successcompletedCall completed normally
not_picked_upno-answerNo one answered
not_picked_upbusyLine was busy
not_picked_upfailedCall failed (bad number, carrier error)
voicemailcompletedWent to voicemail

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Preventing duplicate calls

Pass an idempotency_key to prevent duplicate calls if your agent retries: 
{
  "prompt": "Book a reservation...",
  "recipient_phone": "+14155551234",
  "idempotency_key": "task-12345"
}
Same key within 5 minutes returns the cached response without making a new call.

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Rate limits

60 requests per minute per organization. If you hit the limit, the API returns 429 with a Retry-After header.

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Skill file for AI agents

If your AI agent reads skill files or system prompts, run 
npx skills add https://github.com/yiminghan/callcow-skills --skill agent-call