Create a WhatsApp Voice Assistant with Twilio, VAPI, Google Calendar & OpenAI

WhatsApp Voice Agent with Twilio, VAPI, Google Calendar, Gmail & Supabase

This workflow turns WhatsApp voice messages into an AI assistant using Twilio, VAPI, and modular MCP servers. It handles scheduling, email, and knowledge queries all by voice.

🔎 How it works
WhatsApp → Twilio → VAPI
A WhatsApp Business number (via TwiML app) receives a voice message.
Twilio streams the audio into VAPI for processing.
VAPI → n8n Webhook
VAPI interprets the intent and routes the request to the correct MCP server.
MCP Servers in n8n
📅 Calendar MCP → create, fetch, update, delete Google Calendar events
📧 Gmail MCP → send confirmation or reminder emails
📚 Knowledge Base MCP → query Supabase Vector Store with OpenAI embeddings
n8n → VAPI → WhatsApp
n8n executes the task and returns the result via VAPI back to the user.

🛠️ How to use
Import this workflow into your n8n instance.
Configure a Twilio WhatsApp-enabled number and connect it to a TwiML app.
Point the TwiML app to your VAPI project.
Add credentials for Google Calendar, Gmail, Supabase, and OpenAI in n8n.
Test by sending a WhatsApp voice command like:
“Book a meeting tomorrow at 3pm”
“Send a confirmation email to the client”
“What’s included in the AI receptionist package?”

🎨 Customisation ideas
Add more MCP servers (e.g. CRM, Notion, Slack).
Swap Supabase for another vector database.
Extend Gmail flows with templates or multiple senders.
Adjust the VAPI assistant’s tone and role to fit your brand.

📌 Requirements
Twilio WhatsApp-enabled number + TwiML app (verified in WhatsApp Manager)
VAPI project (assistant configured)
n8n instance (Cloud or self-hosted)
Google Calendar & Gmail credentials
Supabase project
OpenAI API key

💡 Good to know
Twilio must have a verified WhatsApp Business number.
VAPI handles voice infra + intent routing; n8n only executes actions.
The design is modular—easy to expand with new MCP servers.
Works best when tested with short, clear commands.

🚀 Use cases
Hands-free scheduling with Google Calendar.
Voice-triggered email confirmations & reminders.
Conversational knowledge base access.
Extendable to CRMs, team chat, or business workflows.

👉 With this setup, you get a scalable voice-first AI agent on WhatsApp that connects seamlessly to your business systems.