I just called Florence, Italy from my office phone in Orlando, Florida for 2 cents per minute. Google Voice allowed me to do it.
I logged on to my Google Voice account, copied the phone number from the Florence museums’ web site (http://www.polomuseale.firenze.it/), selected my office phone number from the drop down and clicked call. The phone on my desk rang. An announcer reminded me that the call would cost 2 cents per minute. The call was clear (better than my iphone) and the total charge was 10 cents. It was deducted from the $1 credit for signing up for Google’s free service. A payphone call across town costs more than that.
I have a couple more Google Voice invites if anyone is interested.