n8n Workflow: Reduce No-Shows with Sent & Google Calendar

Reduce No‑Shows Automatically: Google Calendar Reminders via Sent

This n8n workflow checks upcoming Google Calendar appointments every 15 minutes, validates customer phone numbers, and sends timely reminder messages through Sent. It also handles inbound Sent replies to confirm or reschedule appointments by updating the Google Calendar event details—helping you cut no‑shows without manual follow-up.

What this workflow does

• Runs every 15 minutes and also triggers immediately when Sent receives an inbound customer message.
• Loads and validates settings such as your Google Calendar ID, business timezone, Sent template name, and a reschedule URL.
• On scheduled runs, it fetches upcoming Google Calendar events and determines whether a reminder is due (around 24 hours for the first reminder, and around 2 hours for the final reminder).
• It intelligently skips events that are cancelled, all-day, have an invalid phone number, are already confirmed, or have a reschedule requested status.
• For eligible appointments, it validates the customer phone number using Sent number lookup (E.164), then sends the reminder using a Sent message template with an idempotency key.
• When a reply comes in, it parses the message for confirmation, reschedule requests, or opt-out keywords—and stops immediately for opt-outs.
• It then matches the sender phone number (and reference code when needed), updates the event description with SENT status, and responds with either a confirmation message or a rescheduling link.
• If no matching appointment is found (or multiple matches exist without a reference code), it sends a clarification message or ignores unrelated inbound messages.

Use cases

• Clinic, salon, or appointment-based services reducing missed appointments with two-stage SMS reminders.
• Teams that want to confirm attendance or enable rescheduling directly from inbound customer replies.
• SaaS operators using n8n to manage operational messaging around Google Calendar events.

Technical details

• Category: n8n automation workflow
• Tech stack / nodes: if, set, code, no op, sticky note, sentdmn8n-nodes-sentsent
• Integrations: Google Calendar + Sent (reminders, inbound replies, number lookup)
• Behavior: scheduled polling every 15 minutes + inbound trigger handling; event description updates; opt-out detection