I have been *very* happy with the Global Riiing card I bought from Telestial. Not only are most calls made outside the USA very cheap, but usually incoming calls are free. This really extends the time you can use the card!

That card is prepaid, but I think there are others now with slightly higher rates that are post-paid.

I tried buying prepaid local SIM cards before for each country I was in, but it is usually a pain. You can't recharge them unless you pay cash, or online you need a credit card with a mailing address from that very same country. Also, roaming in other countries is just too high.

But also on Telestial, you can buy these local country SIM cards too, before your trip.