Enable Attendance Confirmation for Appointment Reminders

Click Bookings → Booking Settings.
Select the Settings tab.
In the Appointment Reminder section, enable one or both of the appointment reminders (see image below).
Select the type of appointment reminder to send in the Reminder Type dropdown menu, or allow your clients to choose at the time of booking.
Check the box labeled Enable attendance confirmation.

Enabling the attendance confirmation feature will do the following:

For every appointment reminder, the system will add an attendance confirmation question at the end, giving your client a chance to confirm or cancel the appointment.
Confirmed appointments will display a check mark by the client's name in the calendar.
Confirmed appointments will also display a checkmark by the client's name in the appointment list page.
The appointment list page will have two new items under the Status filter, allowing you to filter appointments by attendance confirmation status.
Confirmed appointments will have an Attendance Confirmed label in the appointment details dialog.
You can opt in to a notification email sent to staff members when attendance is confirmed. See this option in More → Settings → Notifications. This is disabled by default.

Below are examples of what to expect when using the attendance confirmation feature with each appointment reminder method:

As part of the automated phone call, your client will be asked the following:
- Please say 'confirm' to confirm your attendance or cancel to cancel your appointment.
Please note that the cancellation grace period is still respected, so if the client tries to cancel via the reminder after the grace period, they will receive a message saying that the appointment cannot be canceled.