I have had good luck with Lebara in Europe, and they seem to have a good offer in Australia. The Lebara website is at
Lebara Mobile - low cost international phone calls from your mobile.
Looks like:
*Cheapest SIM cost is $10 with $10 credit - so, essentially SIM card is free.
*International SMS is 15 cents.
*All calls have a 25 cent "flag tariff", then 5 cents per minute to US, 5 cents to UK landline (19 cents mobile), 15 cents Australian landline and mobile, first 10 minutes Lebara to Lebara free plus flagfall.
*"GPRS" (unclear if there is 3G) is 10 cents per MB.
Anyone out there think that any of the other companies have a better offer? If so, how is it better?