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

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Created by: Nabin Bhandari || knabinbhandari

Nabin Bhandari

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Last update 7 days ago

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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

  1. WhatsApp → Twilio → VAPI
    • A WhatsApp Business number (via TwiML app) receives a voice message.
    • Twilio streams the audio into VAPI for processing.
  2. VAPI → n8n Webhook
    • VAPI interprets the intent and routes the request to the correct MCP server.
  3. 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
  4. 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.