Voice AI for appointment booking: Build a Vapi + ElevenLabs Agent that books slots and sends reminders 24/7

Description and use

Automated voice booking system using Vapi, ElevenLabs, n8n, Google Calendar, and Twilio to create events, send SMS confirmations, and call back with voice reminders.

Problem

Automate phone-based appointment booking, confirmation, and reminders without manual intervention.

Outcome

A 6‑8 hour build that delivers a 24/7 voice‑first appointment system with automated confirmations and reminders, reducing manual workload and improving client experience.

Workflow

• Create Vapi voice agent with intents and webhook URL
• Provision ElevenLabs TTS voice and API key
• Enable Google Calendar API and obtain OAuth credentials
• Set up n8n Docker container and configure credentials for Vapi, ElevenLabs, Google Calendar, Twilio, (optional) OpenAI
• Build n8n workflow: webhook node → function node to normalize date/time → Google Calendar event creation → Twilio SMS confirmation → scheduled reminder branch that calls back using ElevenLabs TTS

Evidence

You can wire Vapi's speech-to-intent engine to ElevenLabs' neural text-to-speech, then glue the two together with an n8n workflow that talks to Google Calendar and Twilio.

Source