Selecting the SMS Reminder option means that you will receive an SMS text message 10 minutes before your parking expires helping you avoid a parking fine. You then have the option of replying to the SMS with another SMS, in the usual format, to extend your parking time. To top-up, you need to send the SMS before the parking expires, otherwise, if there is a parking time limit, Council ByLaws may require you move the vehicle before making another payment.
For Brisbane customers, this is a Premium service and is charged as 25c per SMS. It is added to the cost of the parking.