Agent Calling

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.

Setup

Create a CallCow account

Connect a phone number

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

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.

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.

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.

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.

Call statuses

`call_status`	`provider_status`	What happened
`success`	`completed`	Call completed normally
`not_picked_up`	`no-answer`	No one answered
`not_picked_up`	`busy`	Line was busy
`not_picked_up`	`failed`	Call failed (bad number, carrier error)
`voicemail`	`completed`	Went to voicemail

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.

Rate limits

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

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

Getting started

Workflow Guides

Forms

Inbound Contacts

Working With Phone Numbers

Bluk Calls

Integration Guides

Organization Support

Overview

Setup

Making a call

Writing good prompts

Good prompts

Bad prompts

Getting call results

Call statuses

Preventing duplicate calls

Rate limits

Skill file for AI agents

​Overview

​Setup

​Making a call

​Writing good prompts

Good prompts

Bad prompts

​Getting call results

​Call statuses

​Preventing duplicate calls

​Rate limits

​Skill file for AI agents

Overview

Setup

Making a call

Writing good prompts

Getting call results

Call statuses

Preventing duplicate calls

Rate limits

Skill file for AI agents