No. Although Virgin Mobile run on the Optus network they’re still a separate company and as such are locked to Virgin Mobile SIM Cards. However unlocking is available through either paying an $80 fee up front or recharging with $80 Virgin Mobile credit. Once either of these has been done you will need to call customer service and ask them to unlock it (it is not automatic). Once the phone is unlocked you can use any SIM card you like.