put https://sandbox-api.onsched.com/consumer/v1/appointments//book
Use this endpoint to Book an appointment. Only appointments with an "IN" status, Initial, can be booked. A valid appointment id is required. Use the appointment id returned from the initial POST /consumer/v1/appointments endpoint. Other pertinent fields can also be updated at the time of booking by including them in the post body. Note: If no name or email address was provided in the initial Post Appointment, it will be required in the post body.
For more information: Appointments Overview