In Reply to: I phone 4 text costs posted by Spikethirtynine on Monday, 6. September 2010 at 19:11 Bali Time:
If you are with Optus they charge a 55 cent roaming fee for every sms you send and call costs from Bali are $1.32 per minute. These costs are not included in any "cap" plan you may have.
I assume the other Australian carrieirs costs would be similar.
As has been mentioned above, use a local sim or Skype on free wifi, so much cheaper than using your Australian account on international roaming.
Also with iphone if you take them and have a data plan enusre Data Roaming is switched off, otherwise you will need to apply for another home loan to pay your phone bill when you arrive home.