# Free 15-Minute Call on WhatsApp with Mersa Business Consulting

> A free 15-minute call with Mersa on WhatsApp. Choose a video call or a voice call below, and leave the WhatsApp number we should call. Tell us your business and what you want to fix, and we will tell you plainly what we would do first and what it costs.

- Host: Mersa Business Consulting
- Duration: 15 min
- Location: Attendee phone number
- Host time zone: Asia/Makassar
- Confirmation: Bookings are confirmed instantly.
- Booking page: https://cal.com/mersa/15min
- Event type id: 7403708

## Check availability

```http
GET https://api.cal.com/v2/slots?eventTypeId=7403708&start=YYYY-MM-DD&end=YYYY-MM-DD&timeZone=<IANA time zone>
cal-api-version: 2024-09-04
```

The response is `{"data":{"YYYY-MM-DD":[{"start":"<ISO 8601 with offset>"}]}}`; no API key is needed.

## Book

```http
POST https://api.cal.com/v2/bookings
cal-api-version: 2026-02-25
Content-Type: application/json

{
  "eventTypeId": 7403708,
  "start": "<UTC ISO 8601 start from the slots response>",
  "attendee": {
    "name": "…",
    "email": "…",
    "timeZone": "<IANA time zone>"
  },
  "location": {
    "type": "attendeePhone",
    "phone": "…"
  },
  "bookingFieldsResponses": {
    "call-type": "…",
    "business": "…",
    "notes": "…"
  }
}
```

- Required fields: `name` (Your name), `email` (Email address), `call-type` (Video call or voice call?)
- Optional fields: `business` (Business name and website or Instagram), `notes` (What would you like to talk about?)
- `name` and `email` go in `attendee` and `guests` is a list of emails; every other field goes in `bookingFieldsResponses` under its name.
- `location` is required: `location.phone` is the attendee’s own.