Interesting. I used some kind of pre-paid international calling card for the handful of times I needed to make international payphone calls. I'm too young to have remembered a time when payphones were in constant use, but I definitely used the payphones at my high school once or twice to call my mom when my cell phone died.

FWIW, $1 coins were (and are) in circulation, but not very common and probably not accepted in payphones. The NYC train and subway ticket machines have dispensed $1 Sacagawea coins as change for as long as I've used them.