I would like to understand if Optus prepaid SIM cards expire? I understand that credit expires after 28 days etc. but if the phone is not topped up what is the period between top ups when the sim card expires?
6 months from the expiry of your last recharge
It's mentioned on your plan CIS @deeryn.
For example, the Optus Prepaid Epic Data plan
" To keep your service active, you need to recharge 186 days from your credit expiry, otherwise you may require a new SIM card to use the service and you may not be able to continue using your mobile number. "
It's also worth mentioning that SIM cards also have a set expiry date. If the SIM isn't activated before the expiry date, you'll need to purchase a new SIM card. If you purchase a SIM from a retailer other than Optus. It's always worthwhile checking the SIM expiry date.