Generally all sims with mobiles can interpolate, however if the device is prepaid then generally it's locked to the respective carrier. One way of finding out is if you have a friend with a Aldi or Telstra sim, bang it in and see if it works? If it request a network pin or denies service it's a good chance you'll be required to organise the appropriate unlock code.
Our prepaid range is locked to Optus. Currently our range of available phones can be found on our Website here. For further information on organising a phone unlock, please see see our help page here.