In Reply to: Yes as long as your... posted by remi on Monday, 29. June 2009 at 18:19 Bali Time:
You can test to see if your phone is locked by swapping your Optus SIM for a SIM from another company such as Telstra or 3.
If you mobile does not work with another company's SIM, your phone is locked. An Optus shop can unlock it for a fee.
Alternatively, if you have an old unlocked phone, take it to Bali.