Voice Assistant Appointment Booking via Google Calendar + Sheets

Turn voice calls into scheduled appointments—automatically

This n8n workflow exposes a webhook that your voice assistant can use to check availability, book, reschedule, or cancel appointments by syncing Google Calendar events with a Google Sheets bookings log—returning a single spoken-style confirmation sentence for each tool call.

What this workflow does

• Receives voice-assistant tool calls via webhook: A POST request provides a tool call name and arguments.
• Normalizes the payload: The workflow extracts the toolCallId, function name, caller phone number, requested datetime, and other fields, then loads existing bookings from Google Sheets.
• Checks availability (check_availability): Reads upcoming Google Calendar events, calculates the next open time slots within configured business hours, and skips weekends and conflicting times.
• Books appointments (book_appointment): Validates the requested datetime and name, checks for scheduling conflicts in Google Calendar, and either offers an alternative or creates a new calendar event.
• Logs bookings to Sheets: When created, it appends a row to the Bookings tab with appointment details, the event ID, and status.
• Reschedules or cancels: Finds the caller’s existing booking in Google Sheets by matching the last 7 digits of the phone number, then updates or deletes the matching Google Calendar event and returns a confirmation message.
• Returns a webhook response: Responds with JSON containing the toolCallId and a single human-readable sentence, including graceful error messaging for unknown functions.

Use cases

• AI/voice front desks that schedule service appointments without manual admin work
• Phone-based booking that can handle reschedule and cancel requests reliably
• SaaS operators needing a simple availability + booking log using Google Calendar + Sheets

Technical details

• n8n nodes/tools: webhook, if, set, code, switch, and sticky note
• Integrations: Google Calendar (create/read/update/delete events) and Google Sheets (Bookings tab log and lookup)