Australian Premium SMS messages are those messages that are sent to, or received from, numbers starting with 19, for example 19XXXX or 19XXXXXX. When mozone is enabled it will block all outgoing SMS to 19 numbers, except if you are sending STOP to the 19 service.
mozone will block any incoming Premium SMS messages which you have subscribed to prior to downloading mozone or subscribed to on the web, not using your mobile. mozone will then display the number from which the SMS originated.
You will still be billed for this SMS and you should therefore send STOP to the 19 number to end the subscription as soon as possible. This will prevent future messages from being delivered from this specific 19 number.