Grab yer quarters, Dave's Garage has a working payphone! And it even accepts incoming calls, if you can figure out the new number ;-).
I found it brand new in the box, a spare for something. The big problem is that they expect to connect, via a built-in modem, to the central office to get billing and rate information before they'll even THINK about letting you make or receive a call.
To get around that, I burned a custom ROM for it in my DigiPro (thankfully, found some compatible EPROMs on eBay). It stubs all that out and customizes the onscreen messages.
Next, I attached an HT802 ATA to my LAN, a little box with Ethernet in and two phone ports with a dial tone. The only catch is that you have to provide a VoIP connection via the internet to the little ATA box. So I made that happen, signed up for some cheap service, and now my major expense is the 911 tax.
I made a custom "Dave's Garage" plate for it, programmed the VFD display to welcome you to the shop, and it works great!
....as long as you bring a quarter!
Is there enough here for an episode on it? I don't know if people are nostalgic for payphones!