Would anyone be surprised to find that there are still semi-postpay coin phones in use in the U.S.? I found one while driving home from viewing the eclipse on Monday. It's an AE fortress payphone, with a semi-postpay instruction card. Has a dial tone and can make calls. Long distance calls are barred (I assume you would make them via the operator), and I didn't have anyone local to call, so I wasn't 100% able to confirm the semi-postpay operation, but I'm pretty sure it was still set up that way. The phone is in a really neat phone booth that is actually built into a corner of the CO building in Hampton, NE.
Ringback can be activated by dialing the phone's own number and hanging up. That's about the only interesting thing I found in the couple of minutes that I had available to play with it.