I apologize if this has been covered somewhere else, but my search attempts didn't yield any recent information.

In about 10 days, I'm heading on a two-week trip to Buenos Aires, Iguassu and Rio de Janiero and I was wondering if anybody has any tips on pre-paid SIM cards for these locations. I'm not expecting to have much cell coverage in Iguassu.

I have an old unlocked Siemens S46 which has been great. It operates on the 900 frequency. I also have an unlocked Treo 600, which is quad-band, but I'd prefer to leave that one at home, if 900 will work for both countries.

I've found a few operators on the internet, and it looks like it will cost 60-65 cents per minute to call back to the US, but I can't seem to find if they offer just a pre-paid SIM.

Any info would be much appreciated.