I am using a $10 recharge for international call zone A ( to call back to Thailand ). It is last for 30 days and I can call up to 200 minutes each recharge...The unused minutes can be rolled over up to 1000 minutes.
On the basic plan, I selected recharge $30 for 6 months => it includes 100 minutes my time and $30 worth of call. My time unused minutes can be rolled over as well, up to 500 mins (unsure). I normally finish my time credit before the next recharge ( 6 months).
If you are interested in changing your plan, you have to call a customer service number...Optus customer services is Indian, New Delhi, based 100%. Don't be scare they are good....If you have a problem, like cannot understand what they are saying, just simply say "pardon" or "could you slow down, I can't get you". They will be slow down....
They will ask some basic information, Full name, Date of birth, address, or any identification that you have used when registering your mobile number.