# Retellai Webhooks Events

> Retell AI webhooks events — AI voice agent and phone call automation. Use when working with Retell AI for voice agents, phone calls, or telephony. Trigger with phrases like "retell webhooks events", "retellai-webhooks-events", "voice agent".

- Skill: `gabrielmoreira/retellai-webhooks-events` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add gabrielmoreira/retellai-webhooks-events`
- Raw SKILL.md: https://api.skillmd.com/api/skills/gabrielmoreira/retellai-webhooks-events/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- License: MIT
- Author: gabrielmoreira (https://skillmd.com/u/gabrielmoreira)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/gabrielmoreira/retellai-webhooks-events

---

# Retell AI Webhooks Events

## Overview

Handle Retell AI webhook events for call lifecycle, transcripts, and function execution.

## Prerequisites

- HTTPS webhook endpoint
- Agent configured with webhook URL

## Instructions

### Step 1: Configure Webhook URL

```typescript
// Set webhook URL in agent configuration
await retell.agent.update(agentId, {
  webhook_url: 'https://your-app.com/webhooks/retell',
});
```

### Step 2: Webhook Endpoint

```typescript
import express from 'express';

const app = express();
app.post('/webhooks/retell', express.json(), async (req, res) => {
  const { event, call } = req.body;

  switch (event) {
    case 'call_started':
      console.log(`Call started: ${call.call_id} from ${call.from_number}`);
      break;

    case 'call_ended':
      console.log(`Call ended: ${call.call_id}`);
      console.log(`  Duration: ${call.duration_ms}ms`);
      console.log(`  Status: ${call.call_status}`);
      if (call.transcript) {
        await saveTranscript(call.call_id, call.transcript);
      }
      break;

    case 'call_analyzed':
      console.log(`Analysis ready: ${call.call_id}`);
      console.log(`  Summary: ${call.call_analysis?.call_summary}`);
      break;

    default:
      console.log(`Unhandled event: ${event}`);
  }

  res.status(200).json({ received: true });
});
```

### Step 3: Handle Function Calls During Conversation

```typescript
// When agent triggers a function, Retell calls your URL
app.post('/functions/book-appointment', express.json(), async (req, res) => {
  const { patient_name, phone, date, time } = req.body.args;

  // Process the booking
  const booking = await bookAppointment(patient_name, phone, date, time);

  // Return response for agent to speak
  res.json({
    result: `Appointment booked for ${patient_name} on ${date} at ${time}. Confirmation number: ${booking.id}`,
  });
});
```

## Output

- Webhook handling for call lifecycle events
- Transcript storage on call completion
- Function execution during live calls

## Error Handling

| Issue | Cause | Solution |
|-------|-------|----------|
| No webhook events | URL not configured | Set webhook_url on agent |
| Function timeout | Slow backend | Respond within 5 seconds |
| Missing transcript | Short call | Transcript only for calls > 5 seconds |

## Examples

### Process a duplicate webhook delivery safely

Verify the webhook signature, derive a stable event identifier, and record the
event before invoking any downstream side effect. When the same identifier is
received again, acknowledge it without re-sending a notification, creating a
booking, or storing another transcript copy. Send only redacted event metadata
to observability systems, and alert on sustained signature failures or delivery
latency rather than logging the raw call payload.

## Resources

- [Retell AI Documentation](https://docs.retellai.com)
- [retell-sdk npm](https://www.npmjs.com/package/retell-sdk)

## Next Steps

Common errors: `retellai-common-errors`