In the US, the largest operator with international compatibility (GSM
technology) is probably T-Mobile. If you have a T-mobile US subscription
with international roaming enabled, and if your phone is a tri-band model,
you can roam in more than 100 countries. I've used my T-Mobile Motorola
"TimePort" World Phone in many European countries. Australia is a GSM
standardized country, so roaming there is not an issue.

There a couple issues, though. First, you have to make sure the phone you
purchase has multi-band capabilities. Second, you have to make sure your
subscription has international roaming activated. Many cellular carriers are
reluctant to enable international roaming for a brand new subscriber because
of the risk of fraud. There are ways to verify that you are not a fraudster,
however, so don't take "no roaming for 90-days" for an answer.

Jack

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