This is an example of the few places where something like this is feasible.
free-to-use pay phones
What an oxymoron. I suggest the term "public phone".
Look at the device in TFA. That's a pay phone, which is also a way of describing a specific range of hardware types.
Phones-formally-known-as-pay
Look at the device in TFA. That's a pay phone, which is also a way of describing a specific range of hardware types.