Automate WhatsApp booking system with OpenAI and Cal.com: n8n workflow

Automate WhatsApp booking system with OpenAI and Cal.com

Started by another system calling it, and works across Google Sheets. It puts OpenAI behind a retrieval step, so answers are drawn from documents you supply rather than from the model alone. 22 steps, 2 branches: large, and worth reading before you trust it with anything live.

LargeCalls a model: OpenAIRetrieval

The flow

Starts it 5Model 4Logic 5Service 8

The steps in the order they run, from what starts it.

1Webhook Trigger (WhatsApp Input)WebhookStarts it
2LLM: GPT-4o Chat ModelLm Chat Open AiModel
3AI Conversation MemoryMemory Buffer WindowModel
4Create New Prospect in Google SheetGoogle Sheets ToolService
5Update Prospect with Booking DetailsGoogle Sheets ToolService
6Fetch Available Time SlotsTool Http RequestModel
7Trigger: Check Appointments Every HourSchedule triggerStarts it
8Switch: Confirm vs Chat FlowSwitchLogic
9AI Booking Assistant (Dr Firas)AgentModel
10Read Upcoming Appointments from SheetGoogle SheetsService
11Retrieve Prospect DetailsGoogle SheetsService
12Send Response to WhatsAppRespond To WebhookStarts it
13Filter Appointments Within Next 2 HoursCodeLogic
14Normalize Booking Time (UTC Format)CodeLogic
15Send SMS ReminderSms77Service
16Send BookingHttp RequestService
17Mark SMS as Sent in SheetGoogle SheetsService
18Format Date for Readability (Display)CodeLogic
19Check Booking Status (Success or Error)SwitchLogic
20Webhook Response: Booking ConfirmedRespond To WebhookStarts it
21Webhook Response: Booking FailedRespond To WebhookStarts it
22Mark Booking as Confirmed in SheetGoogle SheetsService

How it's built

Starts on: Another system calling it
Steps: 22, with 2 branches
Size: Large: read it before trusting it with anything live
Connects to: Google Sheets
Model: OpenAI
Retrieval: Answers are drawn from documents you supply, not from the model alone

Questions

What does it need to run?

An n8n account, plus your own Google Sheets account, and a key for OpenAI. You connect your own accounts after importing it; none are included.

What starts it?

It starts on another system calling it.

Does it use AI?

Yes. It calls OpenAI. Its answers draw on documents you give it, not on the model alone. Model calls are billed by the provider, not by n8n.

How long does it take to set up?

Take your time. At 22 steps it is large: read it before trusting it with anything live.

How do I import it?

Copy the workflow, open a new workflow in n8n and paste. The steps appear on the canvas, ready for your own accounts.

Before you run it

Nothing here has been tested by us. It is somebody's working automation, read and described from its own steps. Treat the connections it wants as a list of accounts it will touch, and read the 22 steps before you point it at anything that matters.