Retell AI Webhooks Events Skill

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

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

Step 2: Webhook Endpoint

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

// 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 |

Resources

Next Steps

Common errors: retellai-common-errors

Agent Skills: Retell AI Webhooks Events

Install this agent skill to your local

Skill Files