Vapi Call Creation

Initiate outbound phone calls, web calls, and batch calls using Vapi's API. Connect your voice assistants to real phone numbers and test them programmatically.

Setup: Ensure VAPI_API_KEY is set. See the setup-api-key skill if needed.

Quick Start — Outbound Phone Call

cURL

curl -X POST https://api.vapi.ai/call \
  -H "Authorization: Bearer $VAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "assistantId": "your-assistant-id",
    "phoneNumberId": "your-phone-number-id",
    "customer": {
      "number": "+11234567890"
    }
  }'

TypeScript (Server SDK)

import { VapiClient } from "@vapi-ai/server-sdk";

const vapi = new VapiClient({ token: process.env.VAPI_API_KEY! });

const call = await vapi.calls.create({
  assistantId: "your-assistant-id",
  phoneNumberId: "your-phone-number-id",
  customer: {
    number: "+11234567890",
  },
});

console.log("Call created:", call.id);

Python

import requests
import os

response = requests.post(
    "https://api.vapi.ai/call",
    headers={
        "Authorization": f"Bearer {os.environ['VAPI_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
        "assistantId": "your-assistant-id",
        "phoneNumberId": "your-phone-number-id",
        "customer": {"number": "+11234567890"},
    },
)

call = response.json()
print(f"Call initiated: {call['id']}")

Call Types

Outbound Phone Call

Requires an assistant, a Vapi phone number, and a customer number.

{
  "assistantId": "assistant-id",
  "phoneNumberId": "phone-number-id",
  "customer": {
    "number": "+11234567890",
    "name": "John Doe",
    "numberE164CheckEnabled": true
  }
}

Web Call

For browser-based calls — no phone number needed. Use the Vapi Web SDK on the client side.

{
  "assistantId": "assistant-id"
}

Client-side (JavaScript):

import Vapi from "@vapi-ai/web";

const vapi = new Vapi("your-public-key");
vapi.start("your-assistant-id");

Transient Assistant Call

Define an assistant inline instead of referencing a saved one:

{
  "assistant": {
    "name": "Quick Test",
    "firstMessage": "Hello! This is a test call.",
    "model": {
      "provider": "openai",
      "model": "gpt-4.1",
      "messages": [
        {
          "role": "system",
          "content": "You are a test assistant. Confirm the call is working and end politely."
        }
      ]
    },
    "voice": { "provider": "vapi", "voiceId": "Elliot", "version": 2 },
    "transcriber": { "provider": "deepgram", "model": "nova-3", "language": "en" }
  },
  "phoneNumberId": "phone-number-id",
  "customer": {
    "number": "+11234567890"
  }
}

Scheduled Calls

Schedule a call for a future time:

{
  "assistantId": "assistant-id",
  "phoneNumberId": "phone-number-id",
  "customer": {
    "number": "+11234567890"
  },
  "schedulePlan": {
    "earliestAt": "2025-06-15T14:00:00Z",
    "latestAt": "2025-06-15T15:00:00Z"
  }
}

• earliestAt — Earliest time to attempt the call (ISO 8601)
• latestAt — Latest time to attempt the call (optional)
• If using assistantId, the latest version of the assistant is used at call time
• For a fixed assistant config, use assistant (transient) instead

Batch Calls

Call multiple numbers in one request:

{
  "assistantId": "assistant-id",
  "phoneNumberId": "phone-number-id",
  "customers": [
    { "number": "+11234567890", "name": "Alice" },
    { "number": "+10987654321", "name": "Bob" },
    { "number": "+15551234567", "name": "Carol" }
  ]
}

Combine with schedulePlan for scheduled batch calls.

Use this /call batch only when the user does not need a persistent Campaign resource. Use the create-campaign skill for campaign-level monitoring, contact outcomes, duplication, cancellation, concurrency, or webhooks.

Call with Metadata

Pass custom data accessible during the call:

{
  "assistantId": "assistant-id",
  "phoneNumberId": "phone-number-id",
  "customer": {
    "number": "+11234567890"
  },
  "metadata": {
    "orderId": "ORD-12345",
    "department": "billing"
  }
}

Managing Calls

# List calls
curl "https://api.vapi.ai/call?limit=10" \
  -H "Authorization: Bearer $VAPI_API_KEY"

# Get a specific call
curl https://api.vapi.ai/call/{id} \
  -H "Authorization: Bearer $VAPI_API_KEY"

# Get call with transcript and recording
curl https://api.vapi.ai/call/{id} \
  -H "Authorization: Bearer $VAPI_API_KEY"
# Response includes: artifact.transcript, artifact.recordingUrl,
# analysis.summary, and costBreakdown when those outputs are enabled

# Delete a call
curl -X DELETE https://api.vapi.ai/call/{id} \
  -H "Authorization: Bearer $VAPI_API_KEY"

Call Response

A successful call creation returns:

{
  "id": "call-uuid",
  "orgId": "org-uuid",
  "type": "outboundPhoneCall",
  "status": "queued",
  "assistantId": "assistant-id",
  "phoneNumberId": "phone-number-id",
  "customer": {
    "number": "+11234567890"
  },
  "createdAt": "2025-01-15T10:00:00Z"
}

Call statuses: queued → ringing → in-progress → ended

Compliance Warning

It is a violation of FCC law to dial phone numbers without consent in an automated manner. Review TCPA consent requirements before launching automated call campaigns.

References

• Vapi Outbound Calls Docs
• Call Features
• Voicemail Detection

Additional Resources

Vapi provides a documentation MCP server that gives compatible AI agents access to the Vapi knowledge base. Use its documentation search for advanced configuration, troubleshooting, SDK details, and anything beyond this skill.

Manual setup: If your agent doesn't auto-detect the config, run:

claude mcp add vapi-docs -- npx -y mcp-remote https://docs.vapi.ai/_mcp/server

See the Vapi MCP integration guide for setup instructions across supported agents.