I've been peripherally involved in an early stages effort to build something similar for the entire nation (https://reportapayphone.com/), and became aware of this just recently. It's a really great example to aspire to, in terms of the level of polish. I do find the time limiting odd; our goal is to identify as many payphones as possible this way.

Unfortunately the state of payphone-related records is extremely poor, with many ostensibly-active PSPs having quietly gone out of business, other PSPs reorganized without reregistering, and states themselves keeping PSP records very poorly. Throw in small-scale COCOT operations and the result is that there really isn't any authoritative database of possible payphones, so this website's map is going to be missing some. It will also include many that are nonfunctional, as today's PSPs seem to do close to zero maintenance and out of service phones stay that way for years.

Some of the nation's largest PSPs have become ghosts, with the phones still operating and able to accept payment, but the PSP completely unresponsive to efforts to contact them. It's a very strange afterlife.