In Reply to: iphone usage posted by frequent_visitor on Wednesday, 8. February 2012 at 22:33 Bali Time:
You will need to take your Optus sim out to put the Bali sim in so you dont need to turn anything off. One tip though, take your optus sim out before you board your flight, because if its still in when you get to Bali you may get some charges if your internet tries to roam or you get a call.
Make sure your phone is carrier unlocked so you can use a Bali sim.